Issa Certified Nutrition Specialist Chapter Preview
Issa Certified Nutrition Specialist Chapter Preview
Issa Certified Nutrition Specialist Chapter Preview
800.892.4772 • ISSAonline.edu
Second Edition
International Sports Sciences Association CERTIFICATION COURSES
John Berardi, PhD, CSCS
Ryan Andrews, MS, MA, RD
Brian St. Pierre, MS, RD, CSCS
International Sports Sciences Association Krista Scott-Dixon, PhD
1015 Mark Avenue • Carpinteria, CA 93013
Helen Kollias, PhD, CSCS
1.800.892.4772 • 1.805.745.8111 (international) • 1.805.745.8119 (fax)
Camille DePutter
www.ISSAonline.edu
John Berardi, PhD, CSCS
Ryan Andrews, MS, MA, RD
Brian St. Pierre, MS, RD, CSCS
Krista Scott-Dixon, PhD
Helen Kollias, PhD, CSCS
Camille DePutter
Nutrition
The Complete Guide
issaonline.edu
Nutrition: The Complete Guide (Edition 2)
Official course text for: International Sports Sciences Association’s Certified Nutrition Specialist program
10 9 8 7 6 5 4 3 2 1
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any electronic, mechanical, or other means, now
known or hereafter invented, including xerography, photocopying, and recording, or in any information storage and retrieval system without the
written permission of the publisher.
DISCLAIMER OF WARRANTY
This text is informational only. The data and information contained herein are based upon information from various published and
unpublished sources that represents training, health, and nutrition literature and practice summarized by the author and publisher.
The publisher of this text makes no warranties, expressed or implied, regarding the currency, completeness, or scientific accuracy of
this information, nor does it warrant the fitness of the information for any particular purpose. The information is not intended for use
in connection with the sale of any product. Any claims or presentations regarding any specific products or brand names are strictly the
responsibility of the product owners or manufacturers. This summary of information from unpublished sources, books, research journals,
and articles is not intended to replace the advice or attention of health care professionals. It is not intended to direct their behavior or
replace their independent professional judgment. If you have a problem or concern with your health, or before you embark on any health,
fitness, or sports training programs, seek clearance and guidance from a qualified health care professional.
About the Authors | iii
As an elite nutrition coach and exercise physiologist, Dr. Berardi has worked with
over 50,000 clients in over 100 countries, including Olympic gold medalists, world
champion UFC fighters, and professional sports teams. He is also an advisor to Apple,
Equinox, Nike, and Titleist.
Dr. Berardi was recently selected as one of the 20 smartest coaches in the world and
one of the 100 most influential people in fitness.
With a PhD from York University in Toronto and 10 years of university teaching,
Krista Scott-Dixon has over 20 years of experience in research, adult education, cur-
riculum design, and coaching and counseling. In addition, she has spent over 20 years
pursuing self-education in health and fitness.
Krista is the author of several books, dozens of popular articles, and many academic
publications. She also inspires readers at her groundbreaking women’s weight training
website, Stumptuous.com.
Ryan is a Registered Dietitian with two master’s degrees. He completed his education
in exercise and nutrition at the University of Northern Colorado, Kent State Universi-
ty, and Johns Hopkins Medicine.
A highly respected coach who has been a part of the Precision Nutrition team since
2007, Ryan’s body of work includes an impressive number of articles, presentations,
books, and certification manuals on the topics of eating, exercise and health.
Brian is a Registered Dietitian with a Masters in Food Science and Human Nutrition
from the University of Maine. He is also a certified strength and conditioning spe-
cialist, a certified sports nutritionist, and the author of five books including the High
Performance Handbook Nutrition Guide.
Brian shares his expertise on a global scale by presenting at conferences around the
world, serving as a nutrition consultant for pro sports teams such as the San Antonio
Spurs, Brooklyn Nets, and Cleveland Browns, coaching professional and Olympic
athletes, and writing for popular publications including Precision Nutrition.
Camille received her HBA in English from the University of Toronto and trained at
the Humber School for Writers. An advisor to Precision Nutrition, Camille lends her
communication expertise to Precision Nutrition publications, course materials and
marketing content.
As a consultant, Camille has helped dozens of top brands and business leaders refine
their messaging and improve their customer relationships. Her work has been pub-
lished extensively in popular websites, magazines and newspapers.
Camille writes for the Precision Nutrition Encyclopedia of Food and is a frequent con-
tributor to the Precision Nutrition blog. She is also the author of the workbook Share
Your Story, and self-publishes at camilledeputter.com.
Dr. Helen Kollias is a researcher and L1 Certification advisor at PN. She is also a
regular content contributor to the blog, where she uses her witty and articulate writing
style to make complex science accessible and entertaining.
Helen holds a PhD in Molecular Biology from York University, specializing in the area
of muscle development and regeneration, and a Master’s degree in Exercise Physiology
and Biochemistry from the University of Waterloo. She has also held research posi-
tions at some of the most prestigious institutions in the world, including John Hop-
kins University and Toronto’s Hospital for Sick Children.
Outside the lab, Helen has played and coached varsity soccer, and has been involved
in fitness and weight training for almost two decades. She also has two daughters with
whom she wants to share her joy of inquiry and experimentation, but above all, she
wants to teach them resilience, bravery, and grit.
Whether it’s the cosine of an angle, Kepler’s laws of planetary motion, or the enzyme
responsible for forming citrate, students’ most common questions about what they’re
learning are:
We, the authors, know these questions well. We’ve asked them ourselves, most often
during our own high school, undergraduate, and graduate studies.
So now, as instructors living in the “real world”, we’d like to level with you: Probably
not.
Unless you become an engineer, you probably won’t need the cosine stuff. Unless you
go to work for NASA, you can probably forget Kepler. And the Krebs cycle? Well, you
won’t need that unless you teach biochemistry.
Well, most of us don’t know what we want to be when we grow up. Work (and life) is
full of surprises.
You never know what career path you’ll follow, or what hobbies you’ll take up.
But there’s another, more inspiring, reason for learning this stuff.
It’s actually kinda interesting. It helps explain your world. And makes you super-fun at
parties.
In fact, when you really dig into this knowledge, you might just change what you want
to do for a living because of it.
This foundational knowledge — about stuff like cells, digestion, metabolism and
whatnot — can feel a little heavy at times. Especially if you’re new to this material. Or
you’re a practical, hands-on kind of person who would rather spend more time doing
than reading.
Hang in there.
The payoff comes in the second section, where that foundational information gets
applied.
We’ll give you case studies. Strategies for working with real-world clients. Question-
naires and assessments to use with your clients. Psychological strategies for getting
clients excited about working with you. And all kinds of other fun things.
Even if you’ll never use the more theoretical material we teach you, you’ll still need
to know the science to apply it under “test conditions” — in other words, when you’re
sitting across from a client.
• how to get your clients on board with your nutrition plans and programs — hopeful-
ly feeling just as inspired as you about making progress and changing their nutrition
habits.
In Section 1, we’ll go through all the nutrition information you’ll need to know, such
as:
• How and why your cells work the way they do
• How carbohydrates, fats, vitamins, minerals, and other nutrients interact with
your cells
• How food becomes energy for maintenance functions, physical work, and repair
• How your body balances out the food you eat with the work it does
• How exercise affects nutritional needs and how nutrition affects exercise
• How to meet clients where they are (not where you want them to be)
• How to keep clients progressing from day one until they reach their goals
Unit objectives
Each unit contains clear objectives at the beginning. This will tell you what to focus
on, and give you goals before you even start reading.
Unit summaries
At the end of each unit, we’ll summarize the most important points from that unit.
These will confirm that you’ve learned what really matters, and give you another handy
tool for review.
Key terms
The first time a key term appears in the text, it is highlighted and a definition provided
in the margin. Familiarize yourself with each key term.
Case studies
Most units end with relevant case studies. These give you “real-life” examples of ap-
plied nutrition.
Each story describes a client’s nutrition challenges, then provides practical solutions to
work through these challenges.
References
We’ll provide a comprehensive list of references used to create this course. If you’re
interested in learning more about nutrition and health, you can look up and read more
of this primary source literature.
Here are some ways to stay on track and on target with your Level 1 journey.
You know your own learning style. (And if you don’t, now’s a great time to discover it.)
Help yourself succeed by building a system that suits you.
Use as many ways of processing the material as possible: reading, writing, thinking
and reflecting, listening, watching, talking about the material, drawing maps and
flowcharts of ideas, etc.
We suggest…
Set up a weekly self-study schedule so you get into a routine. Consistency and struc-
ture will help you move forward steadily and confidently.
As the scientists working on the 1999 Mars lander mission found out when their
precious spacecraft wandered off into oblivion because they mixed up imperial and
metric measurements, details are important.
But details usually aren’t the most important things in this program. You don’t have
to memorize entire units, nor usually recall minute details (such as the exact body
density equation by Jackson & Pollock).
As long as you learn the concepts and study as we recommend, you have a great
chance of doing well on the quizzes.
Plus, you’ll always have your text available for reference. If you get stumped during a
quiz or a client interaction, you can always look things up.
It’s more important to know how to think. How to learn. How to connect ideas.
And to understand why things are important (and how they relate to one another) than
to recall specific details. (Unless detail memorization is your thing. Then go for it.)
Seek to master both the basic science (Section 1) and the applied art of coaching
(Section 2).
If you do, you’ll finish this program as a highly trained professional with the knowl-
edge to support your recommendations; the ability to communicate them effectively
and well; and a foolproof system for delivering outstanding, reproducible results.
Acknowledgements
It’s really important to us that everyone who helped bring this major project to com-
pletion is recognized for their work. Because, as we all know, nothing worth doing can
be done alone.
To this end we’d like to thank Paul Bradbury, Rachael Bell, Phil Caravaggio, Al Cimi-
no, Alwyn Cosgrove, Alison Dungey PhD, Georgie Fear MS RD, Carmelo Galati RGD,
Jonathan Goodman, Sean Greeley, Mariane Heroux PhD, Timothy Jones, Bedros
Keuilian, Helen Kollias PhD, Sarah Maughan MS, Bob Moesta, John Nadalin, Spencer
Nadolsky DO, Tom Nikkola BA, Eric Noreen PhD, Prasanna Paul, Alex Picot-Annand
MS, Pat Rigsby, Francisca Ruff, m.c. schraefel PhD, Chris Spiek, Bryan Walsh ND, and
Erin Weiss-Trainor.
Unit Outline
9. Summary
Objectives
This unit will introduce you to the big picture of good • why good nutrition matters for personal health, as well
nutrition. as community and global health
What is food?
Seems like a dumb question with an obvious answer. Food is stuff we eat that
fuels our body. Right?
Well, that’s one way to think about it. Food contains energy. Or, more correct-
ly, “chemical bonds that, when broken, are used to create ATP, the fuel for our
cells.” (More on that in a later unit.)
But food also includes micronutrients, phytochemicals, zoochemicals, fiber, Zoochemicals: Components
water, and perhaps even organic molecules that we haven’t yet discovered. All of found in animal food sources
these substances play crucial roles in our body, even though they don’t necessari- Organic: Obtained from living
ly “fuel” it directly. things
pressure regulation, energy production, and transport of when you fill your car’s tank with gas, you know more or
other minerals. less how far you can drive.
The list could go on and on. You’ll learn more about But if you’ve spent any time doing “calorie math”, you’ll
these and other nutrients in later chapters. know that trying to calculate precise inputs and outputs
for a human body is frustrating.
While none of these nutrients provide “fuel”, we still
need them to live and thrive. • Maybe you ate more calories than you thought you
should… but got leaner.
When you’re missing key vitamins and minerals, your
• Or you ate fewer calories than you thought you
body doesn’t work properly. You feel rotten. And you get
should… and gained weight.
sick. That’s true no matter how much fuel is in the tank.
• Or you started eating breakfast instead of skipping
Phyto- and zoochemicals it…or vice versa... and dropped a couple of inches off
your waistline.
Phytochemicals (whose name comes from the ancient
Greek phuto, or plant) are nutrients that only occur in According to the simplistic “food as fuel” view, none of
plants. Phytochemicals are one of the main reasons that this should be possible. Yet it happens all the time.
eating fruits and vegetables is good for us.
Human bodies aren’t combustion
For instance, phytochemicals have been shown to:
engines.
• offer DNA protection against free radicals;
They’re complex, dynamic, organic, and infinitely sensi-
• protect against cancer;
tive systems.
• decrease the risk of heart disease; and
For example: Research now shows that all food isn’t creat-
• reduce overall mortality. ed equal, and what we eat isn’t necessarily what we absorb
or use. Dozens — maybe even hundreds — of factors
Zoochemicals (from the Greek zoion, or animal) are
affect how we digest, process, and utilize the food we eat.
nutrients found only in animal products, such as CLA (a
fatty acid), creatine, and carnosine. This means that the fuel, or calorie, value of food
outside the body isn’t necessarily the same as the value
Zoochemicals have been shown to:
inside the body.
• reduce inflammation and blood clotting;
Plus, our body has its own priorities.
• protect against heart disease;
of our bacterial environments shows that each of us has an individual gut flora
“microbiome”, like a fingerprint. Microbiome: The genetic
content of all the microorganisms
that inhabit the GI tract
Changing our microbiome changes our digestion and absorption, and hence our
body composition and health.
• Don’t do this.
Food (and the act of eating) sends instructions that kick off a chemical chain
letter. Each molecule of food contributes to a beautiful cascade of events, sending
all kinds of signals throughout our body.
Make hormones! Trigger immune cells! Switch genes on and off! Tell the work
crew to clean up and the builders to get on standby! Lights! Camera! Action!
It’s like the biggest, busiest movie set you can imagine. And somehow — unlike
many film sets — it runs almost perfectly.
Our body processes millions of calories and (let’s be scientific about this) zillions
of chemical compounds a year, with nearly 100% efficiency. (Just for comparison,
gas-powered engines, like our car, would be happy to hit 30% efficiency.)
Even cooler: Our thoughts, feelings, and environment can affect these process-
es. If we smell a tasty meal, have a positive or negative thought about food (or
anything else), are happy and relaxed or worried and rushing…it affects nutrient
processing.
Food and your body deserve a lot more recognition and honor.
The more we learn, research, and work with clients, the more we’re amazed at the
power of food.
Food is packed with meaning, For a nutrition coach, knowing these stories is relevant.
information, and communication. Crucial. Powerful, life-shaping knowledge.
Every food decision we make sends a message to our Take a few minutes and consider these questions:
body. • What is food?
Every food choice is an opportunity to direct, shape, and • What is food… for you?
remake our health. Our body composition. Our perfor-
• For your clients?
mance. Our wellbeing.
Is it fuel? Is it information? Is it personal freedom? Is it
Food tells a story. shame? Is it self-esteem? Is it comfort?
Many of us in this field are physiologists and biochem- Then consider these questions:
ists. Sure, we look at food through a science lens. But
that’s not our only perspective. • What would you like food to be?
• I’m the social hub for my big family. Come on over Take a minute to answer this question for yourself: What
is good nutrition?
this Sunday for dinner!
• I’m adventurous. I’ll eat anything once. Once, when I We’ve given this question a lot of thought over the years.
was traveling, I ate… As of today, here’s how we answer it:
And so on. Without enough energy coming into the body, we just
don’t work right. Our body starts to shut down processes
These stories are essential information about ourselves, that we don’t absolutely need to survive, such as reproduc-
about our family and friends, and about our clients. tion, some aspects of metabolism, and brain function.
Too much energy coming into the body also causes problems. We can become
resistant to important hormones (such as insulin or leptin). Inflammation may
increase. Plaques can form on vessels and blood pressure can go up. We risk
getting many chronic diseases. Chronic diseases: A long-acting
disease that does not quickly
resolve, e.g., cardiovascular
Good nutrition helps control energy balance. We don’t eat too much or too little. disease, cancers, chronic
We can stay healthy, fit and strong. We feel good, and our body shows it. respiratory diseases and diabetes
• a plate of lentils
• a plate of cookies
• a plate of salmon
• a plate of berries
In some cases, like the cookies, there are lots of calories but few nutrients. That’s
called low nutrient density.
On the other hand, with the kale, there are lots of nutrients but few calories.
That’s called high nutrient density.
Good nutrition helps us balance energy intake and getting enough of these
valuable, essential nutrients.
As a nutrition coach, take a holistic approach. Help your ories they eat come from highly processed foods.
clients balance specific goals with general benefits — • In the US, just over 11% of calories come from fast
perhaps even benefits they didn’t realize were possible. food.
We use this question because it tests perception Good nutrition is sustainable for
against reality. If someone thinks they’re eating really
“healthy”, but they just don’t have the body, health, both us and the planet.
or performance that could be expected, maybe that
Can we keep eating and producing food the way we are
person’s idea of “healthy” doesn’t match reality. Maybe
now? For how long?
they’re not making outcome-based decisions.
Research suggests that we waste between 30 and 50% of
Indeed, lots of people in North America think they have
all food produced.
a really healthy and balanced diet.
Food often travels thousands of miles between the farm and our dinner plate.
While global food production has gone up, hunger and malnutrition are still big
problems worldwide. And more crops than ever before are being grown to feed
livestock (not people).
With a planet that isn’t growing and a population that is, our food decisions need
to be more sustainable and environmentally considerate than ever before.
Luckily, what helps the planet usually helps our body and health as well. That’s why
good nutrition is about finding a diet that is sustainable for us and the planet.
While you’re building up your expertise, here’s a quick list of possible limiting
factors to look for. (We’ll share more examples later on.)
• Some clients will have genetic factors that can make losing weight, gaining
muscle, completely avoiding chronic diseases, or other physical outcomes
easier or harder.
• Some clients will be genetically more or less able to metabolize certain foods
or chemicals, such as caffeine or particular amino acids.
Amino acids: The building
Genes are not destiny. Epigenetic factors — such as nutrition, stress, or a healthy blocks of protein. Organic
environment — can strongly affect genetic expression. So you might carry sev- compounds containing both
eral of the known gene variants for obesity… but you can also choose what to eat COOH and NH2
for dinner, or put on running shoes and get outside. Gene variants: Diversity in gene
sequence within a population
Almost everyone can make daily choices that will keep them as healthy, fit, and or among populations that are
vibrant as possible, for their individual body. most commonly due to single
nucleotide polymorphisms (SNPs)
or copy number variants (CNVs)
Exercise
Activity changes how our body uses nutrients. Active and fit people can eat
more, use nutrients more efficiently and effectively, and keep their metabolisms
healthier than sedentary and unfit people.
At the same time, exercise alone isn’t enough to keep your clients healthy or lean.
(Which is one reason that your work as a nutrition coach is so important.)
Physiology
If you’ve ever had a serious metabolic or hormonal problem, or an imbalance of
neurotransmitters, you’ll know: Physiology is powerful.
Work with, rather than against, your clients’ unique physiological makeup, and
help them understand what’s realistic. (But stay hopeful.)
Take an integrated approach: Collaborate with your clients’ health care provid-
ers, if needed, to work together as a team.
Mindset
Every action starts with a thought. Thoughts become things.
Negative, sabotaging or inaccurate thoughts, self-talk and beliefs can hold your
clients back. Not only do negative mental dynamics affect clients’ behavior, they
also have physiological effects: Our brain and body treat these like any other
stressor, and respond accordingly.
Luckily, as a nutrition coach you can help replace negative mindsets with things
like positive self-talk or better information.
Notice how your clients think, and the stories they tell themselves. Consider how
you can also improve those thoughts and beliefs as part of your nutrition coach-
ing. (We’ll look more at this in Section 2.)
Also consider how you can help your clients move from knowing information to
taking action.
A winning mindset plus a great nutrition action plan… that’s a recipe for success.
Environment
What’s around your clients?
Who is on their team? (Besides you.) How are their relationships at work, home,
school, or elsewhere?
What’s their physical environment like? Are healthy choices close and
convenient?
Most of our daily decisions are unconscious. We don’t think about them. We
just make them. So our environment strongly shapes what we do, eat, and think
about.
Even if your clients really want to make better choices, they’ll probably also need
to adjust their environment to do so.
As a nutrition coach, you’re looking for limiting factors, but also for your clients’
advantages, strengths, and opportunities for success.
How can you take what’s already working, and improve on it?
Now, of course, if you’re looking for strengths and wins, you’ll probably wonder...
The secret:
Here’s why.
• Fitness level and body composition: Some clients are active, strong, lean,
and dense. Some clients have been sedentary for the last 50 years and may be
frail, without a lot of muscle.
• Nutrition knowledge and diet history: Some • “real-life” testing and client experience.
clients will be devout followers of a certain dietary
practice, or a history of trying different diets. Others
Good coaches stay skeptical, think critically, and take a
broad perspective.
have very little nutrition knowledge at all.
• Time: Some clients have an open schedule, ready for Indeed, here’s one crucial piece of evidence:
any kind of health and fitness project. Others have
a crowded daily schedule and countless conflicting The healthiest people in the world
priorities.
don’t have a single nutrition
• Ethnic background and heritage: Our coaches
philosophy.
practice all over the world. Our clients live, and come
from, all over the world. A meal or cuisine that suits Physiologically, the human body can do well under all
an Anglo family may not suit their Hispanic, Somali, kinds of different nutritional conditions.
or Punjabi neighbors. A client from a northern Euro-
We can see this clearly if we look at the traditional diets
pean ethnic group may digest dairy easily, while the
of indigenous groups and ethnic groups throughout the
client of Japanese heritage next to them may not.
world.
• Age: As we age, our metabolisms change, our food
• For example, the Arctic Inuit and African Masai eat
tolerances and appetites change, and our digestive
traditional diets that are high in fat and animal prod-
abilities change.
ucts, with few vegetables.
You get the picture. • Conversely, Kitavans in the South Pacific, the Hadza
of East Africa, and many groups in the Amazon basin
As a nutrition coach, your job is to help your clients — as
(such as the Tsimane of Bolivia) eat traditional diets
unique people — get to their goals. To do what matters
to them, in the way that’s best for them. that are low in fat but high in vegetables and starchy
carbohydrates.
The best coaches don’t have a single • The !Kung of Africa eat traditional diets that are made
up of mostly nuts and seeds.
nutrition philosophy.
This is also true if we look at the world’s Blue Zones,
You might have the approach you like, or one that areas where people live exceptionally long and healthy
worked for you. Great. That’s a solid start. lives.
But good coaches take a flexible approach. They borrow You probably wouldn’t mistake Okinawan cuisine for
the best ideas from everywhere and everyone, and are the Mediterranean cuisine of Sardinia, Italy or Ikaria,
always looking for new insights or tools. They don’t get Greece. Or the Central American cuisine of Costa Rica’s
stuck in dogma. Nicoya peninsula.
Good coaches look at the evidence. This can include: The human body adapts amazingly
• peer-reviewed clinical and scientific research; well to many different ways
• understanding the basis of how and why things work of eating.
(or don’t); and
You can be healthy and fit whether you eat mostly meat
or mostly veggies, mostly fat or mostly carbohydrates, many times a day or just a Carbohydrates: A group of
few times, and so on. compounds including sugars,
starch, and cellulose
Which means that, as a nutrition coach, you shouldn’t really belong to any spe-
cific nutrition camp at all.
When you work with actual human beings, you must be a nutrition agnostic:
• Explore and try anything and everything that could work.
• Be willing to test new methods, even if they fly in the face of current beliefs or
practices.
Don’t focus on the food itself. Or on making sure everyone follows your “nutri-
tion rules.”
When you really care about what you eat, and make mindful, deliberate choices,
you almost inevitably eat better.
Instead, pretty much every camp recommends eating whole, minimally pro-
cessed, nutrient-rich foods — foods with which our body has a longstanding
relationship.
Often, when people start a certain diet program, they just start eating better
overall. They get more nutrients. They may get more variety. Or fresher foods. Or
less-processed foods. Or foods they chose mindfully.
Because of these factors, they feel better. And that’s one reason they start making
wild claims about the rejuvenating power of their new diet.
They didn’t do anything special, really. They often just started getting what their
bodies needed.
We may also eat them on the go, when we’re rushed and busy. So not only are we
eating foods that encourage us to eat more of them, we’re not even really paying
attention to the experience at all.
Conversely, when we’re more aware of what we’re eating; choose a variety of
more satisfying, higher-quality foods; and eliminate nutrient deficiencies, we
almost always end up eating less food overall.
Notice that you don’t need calorie counting here. Focusing on food awareness
and food quality is usually enough for people to tune into their own hunger and
appetite. That means calorie control without the annoying calorie math.
It also means that your clients can stick with this, since almost nobody can count
calories (or wants to) forever.
Good nutrition fits with regular activity like a key into a lock.
And most nutrition programs suggest that people exercise along with eating well.
Learn more about global nutrition and eating habits. Broaden your focus.
Expand your world. (If possible, travel and actually experience different foods,
cuisines, and food philosophies.)
Test your theories and programs. See how they work on actual clients with real
lives and real bodies in the real world. Look for evidence. Gather data and mea-
sure outcomes.
Remember to ask our favorite question: “How’s that Sure, we might check a few labels for the word “organic.”
working for you?” But beyond that… well, many folks think that chicken is
just “protein” that comes in rectangular plastic packages.
And where possible, look for underlying themes that
make all good nutrition programs “work.” (Wait… a chicken is a bird? That has feet, and feathers,
and stuff?)
One key feature about successful diet plans — especial-
ly in the Blue Zones — is that good nutrition connects
people to the food itself. Food as information about the world
So now that you’ve thought about what food is, and what Just as food is information for your body, food is also
good nutrition involves, let’s think about where food information about ecosystems and the environment.
comes from. Or where it goes.
Food is information about how things get produced,
processed and sold all over the world.
The cycle of food
Someone had to grow that fruit or vegetable from your
Check your fridge and pull out a fruit or vegetable. fridge. Other people picked it, and packed it, and trans-
ported it, and sold it.
• Where was it grown?
• How was it grown? Obviously, a full discussion of the social, political, eco-
nomic, and environmental issues involved in agriculture
• Who picked it for you? is beyond the scope of this text. We’ll touch on it briefly,
• How did it get to you? to help you understand a few more parts of the bigger
picture of food. If you’d like to learn more about these
• What steps did it take?
issues, check out the agriculture resources in Unit 17.
• How far did it have to travel?
Sustainability
• What factors ensure you can get more of that fruit or
vegetable? Something sustainable is something that you can do
for a long time. That could be a well-planned nutrition
• Do you think that people could still be eating that
program, of course. Or in this case, a way of growing
fruit or vegetable in 100 years? What about 500?
and producing food.
Why?
Sustainable agriculture is agriculture that we can do for
In the world of nutrition for health, performance, and a long time. It involves things like:
body transformation, we don’t talk much about where
food comes from. Or where it ends up if we discard it. • preserving and replenishing soil with nutrients;
Figure I.2 The food life cycle • minimizing waste and pollution.
At its most basic level, sustainable agriculture is about become more aware of these processes and priorities —
ensuring that we can produce safe, high-quality food for to help them see that choices are at the end of a pathway.
everyone, for a long time to come.
And, if needed, you can help them change those path-
Sustainability in agriculture isn’t just a nice thing to ways to change their choices.
have. It’s what will ensure we can keep eating the things
we want and need to eat. As you look to deepen your own practice and increase
your awareness, think about food within a larger web.
We’ll talk more about sustainability and organic versus
conventional foods in a later unit. We’ll talk more about how to implement small, manage-
able habits later in the course.
Food as a set of choices For now, just get the general idea:
• Think about the big picture of nutrition, food,
We’ve suggested that food is information, and a way of
telling a story. and eating. Notice how adding some context helps
expand your understanding of what nutrition, food,
Here’s another thing to think about: Food and eating is a and eating are all about.
set of choices.
• Think about what might be most important
As a nutrition coach, one of your jobs is to make your for both you and your clients. Notice how there
clients more aware of what they’re doing. Indeed, aware- are lots of options for diverse clients. (Don’t worry,
ness itself can often change people’s behavior. (We’ll talk we’ll help you sort things and focus later.)
about this more in Section 2.)
• Think about how you might work towards
As we’ve stressed, nutrition coaching isn’t about getting those values and priorities as part of nutrition
people to follow “the rules.” It’s about helping them coaching. We know it’s a long-term project. Just
make more conscious choices. Choices that align with start with today… and keep reading.
their values, priorities, and goals.
We (and our clients) think about lots of things before we What is nutrition coaching?
buy and eat a food, such as:
We’ve started to give you some ideas about what nutri-
• what’s convenient; tion coaching is.
• what it costs;
Let’s look more closely now at what the role of nutrition
• what’s healthy (or not); coach involves.
• what we’ve done before (and in that case, we don’t First, congratulations.
really “think” about it);
to help and support them as they improve their exercise Keep learning. Stay up to date.
and nutrition choices. In fact, sometimes those family and
friends can actively sabotage your client’s efforts. Your clients want reliable, current, practical information
they can understand and use.
In the beginning, you may be the only team member a
client has. This means that you should have a process of ongoing
learning, information gathering and filtering, and shar-
You have the power to change lives. ing that knowledge.
• registered dietitians
By helping prevent chronic diseases or nutrition-related
disabilities, or helping them change their relationships • nurses
with food, you might even save their lives sometimes.
• physical therapists
• naturopaths
What does a good
nutrition coach do? Think collaboration rather than competition. You’re all
working together on your client’s team.
Fundamentally, a nutrition coach is a guide for change.
We’ll talk about this more in Section 2. We also suggest you build a professional network to sup-
port your own practice. Look for people such as:
Here are some things that all good nutrition coaches
• business coaches
should do.
• accountants
Be client-centered.
• marketers
This means you’re an advocate and ally of the client. You • web designers
want to help them do what matters most to them… not
what matters most to you. Have good boundaries. Know your scope
of practice.
You listen to them. Try to understand their needs. Try to
understand their lives. You’re not a therapist, medical doctor, or general fixit
person. Good nutrition coaches understand clearly what
You see them as unique individuals, and try to match
they can and can’t do.
your nutrition programming to what’s best for them.
We’ll look more at client assessment and scope of prac-
Help clients take action. tice in Section 2, but here’s a general overview.
Knowledge and information are great, but they’re not
enough. Your clients need to do stuff. What’s your scope of practice?
Good nutrition coaches create clear, goal-driven, evi- You’re probably here because you’d like to be able to
dence-based nutrition plans that clients can immediately talk about nutrition with your clients, and to help them
start putting into action.
improve their food and eating habits. But it’s not always This means you can’t prescribe nutrition for specific
clear what you can and can’t talk about with clients. health conditions and illnesses, such as:
• diabetic nutrition
You can talk about nutrition with your
clients… if you’re qualified to do so. • cancer therapy nutrition
Case Study
Many clients come to us with “diet experience.” carbohydrates. Or reducing fat. Or a specific macronu-
trient ratio.
Some have done lower-carbohydrate diets, like the At-
kins Diet. Others have done low-fat diets, like the Ornish All three plans create a negative energy balance in three
Diet. And others have done more “balanced” plans, like ways:
the Zone Diet.
1. When clients follow a “weight loss plan”, they usual-
One client followed all three plans at one point or an- ly eat less. This decreases “energy in.”
other, along with exercise.
2. Exercise increases “energy out.”
In each case, the process and results were the same:
3. Both Atkins and Ornish ask dieters to restrict either
• He followed the diet. dietary carbohydrate or dietary fat. The Zone plan
asks dieters to eat a specific ratio of macronutri-
• He lost about the same amount of weight.
ents — which usually means that people eat less of
• He gained it all back… and usually more. whatever they were eating “too much” of. Is it any
wonder that by asking dieters to avoid eating some-
• He tried another diet.
thing, they’ll end up eating less?
No matter what diet he tried — despite how “differ-
ent” these diets were from each other — the same stuff It wasn’t some magical macronutrient mix that made the
happened. client lose weight. It was plain old energy deficit. (You’ll
learn more about energy balance in an upcoming unit.)
How can this be?
However, all three experiments ultimately failed.
Well, instead of focusing on what makes diet plans dif-
ferent, let’s look at what makes them similar. Each time, the client rebounded. He gained more
weight after losing it. After giving up, he got off track,
The client got the same results with different diets stopped exercising, and started eating poorly again.
because all three plans forced him to follow a key rule of
good nutrition: However, it wasn’t the food that caused this rebound.
It was many other lifestyle factors. The problem wasn’t
All three plans, together with his exercise plan, forced him what he was eating necessarily… but how he was eating
to control his energy balance. and living.
To lose weight, we need a negative energy balance. In Only when we started to address these key factors did
other words, we need to take in less energy (in the form the client change his fundamental habits… and lose his
of food) than we expend (in the form of metabolism and excess body fat for good.
activity).
In this program, you’ll learn that both the what (i.e., the
If someone loses weight, they’ve somehow managed to food itself) and the how (i.e., how we eat and live) are
get into negative energy balance. crucial elements in change.
In this case, that’s what did the trick — not the lack of
What this program You should finish this course with both a better under-
standing of exercise nutrition and the tools used to deliv-
will cover er nutritional recommendations.
Here’s what we’ll do in the rest of this textbook and this Important note
course.
Completing this course will not qualify you as a
• Dispel common myths and fallacies associated with
registered dietitian, licensed dietitian, or licensed
nutrition.
nutritionist. Check with the licensing bodies in your
• Give you the foundational knowledge you’ll need area if you are hoping to get licensed.
to make general nutritional recommendations to a
variety of clients.
Nor will this course allow you to provide medical
nutrition therapy.
• Provide and explain nutrition theory and science.
Instead, this course will provide you with continuing
• Give you a clear process and walk you through the
education in the field of nutrition.
steps of preparing for, assessing, evaluating, and
making recommendations for clients. It will enhance your credibility, your confidence, and
your skill set.
• Give you a set of resources that you can use almost
immediately in your coaching practice (if you have And it will help you overcome the biggest limiting factor
one already). your clients face every day: poor nutrition.
Summary
Food is fuel, but it’s so much more than that. Food gives • give us nutrients;
us important substances such as micronutrients, phyto- • help us look, feel, and perform our best;
and zoochemicals. We need all of these nutrients to live
and thrive. • are outcome-based;
• helps control appetite and food intake; and • Offer general nutrition advice, not medical nutrition
therapy.
• promotes regular exercise.
• Collaborate with your professional network of other
Being a nutrition coach is an important job. You’re often health care providers.
the first person a client sees when they want to look, feel,
and / or perform better. You’re part of your client’s social • Learn the rules and regulations of your area.
support system. You have the power to change lives.
This program will:
A good nutrition coach will: • help to dispel common myths and fallacies
• be client-centered; • give you the foundational knowledge you’ll need
• help clients take action; to make general nutritional recommendations to a
variety of clients
• keep learning; stay up to date;
• provide and explain nutrition theory and science
• collaborate; and
• give you a clear process for preparing, assessing,
• have good boundaries; know your scope of practice.
evaluating, and making recommendations for clients
What’s your scope of practice? • give you resources that you can use almost
• You can talk about nutrition with your clients… if immediately
you’re qualified to do so.
• give you a better understanding of exercise nu-
• Know your options where you live. trition and the tools used in delivering nutritional
recommendations
1 Cells, p23
3 Energy Transformation
and Metabolism, p77
6 Macronutrients, p155
7 Micronutrients, p197
Cells
24 | Unit 1
Unit Outline
5. Parts of cells
1. Objectives
6. Body function
2. Cell structure and function
7. Cell types
3. How the body is organized
8. Summary
4. Nutrition and cellular interaction
Objectives
In this unit, you’ll learn how your body’s cells: You should be able to recognize:
• get nutrients from the food that we eat, and • the main cell organelles;
• use these nutrients for the raw materials and fuel to • what each organelle does; and
keep us alive.
• how each organelle interacts with organic molecules
At the end of this unit, you should have a working knowl- to do its most important jobs in the body.
edge of how humans are organized, from the organismal
You’ll start to build the foundation of physiological knowl-
level all the way down to the atomic level.
edge that you’ll need to make and apply nutrition plans.
Adult humans have trillions of cells. All work together to keep us alive.
F. Organ
Tissues combine
to form organs.
Example: heart.
E. Tissue
Cells form tissue.
Example: cardiac
muscle tissue.
D. Cell
Organelles work together
to form cells. Example:
cardiomyocytes (cardiac
muscle cells).
C. Organelle
Molecules and atoms combine
to form organelles.
Example: nucleus.
B. Molecule
Atoms combine to form a molecule.
Example: deoxyribonucleic acid
(DNA).
A. Atom
Chemicals, such as carbon, G. Organ System H. Complex Organism
hydrogen and oxygen, are Organs work together to form Organ systems sustain
the basic units of matter. organ systems. complex organisms.
Example: carbon. Example: circulatory system. Example: you.
Figure 1.1. Organization of the human body. Atoms combine to form molecules. Molecules and atoms combine to form organelles.
Organelles work together to form cells. Similar types of cells form tissue, and tissues join to make up the various bodily organs. Groups of organs
that work closely together form organ systems, and it is these organ systems that ultimately sustain an organism.
We need proper nutrition for our cells to work proper- And the body lives within even larger systems.
ly. This means getting the right nutrients in the right
amounts. Ecosystem
When we eat well, our cells function well. When we Our body lives within ecosystems — dynamic, interac-
don’t eat well, problems happen. tive, interconnected networks of living things.
Healthy cells means healthy metabolism. Unhealthy cells Some scientists even think that given how many bacteria
means unhealthy metabolism. are on us and in us, humans aren’t even really “separate”
bodies at all!
For the purpose of this program, we can say that you as a human are a distinct
organism. (Bacterial buddies notwithstanding.)
As an organism, the human body can reproduce, replace, and repair itself, all to
homeostasis: The body’s ability stay alive and to maintain homeostasis: the state of balanced function in the body.
to maintain a stable and constant
internal condition
Organ systems
Complex organisms, such as humans, are made up of organ systems.
• Integumentary system: This system protects the body from external
damage. It includes your skin, hair, nails, sweat glands, and other external
structures.
• Skeletal system: This system gives the body a rigid structure so that it can
move and hold itself up. It includes your bones, tendons, ligaments, and other
structures.
• Muscular system: This system moves us, whether it’s to move you across the
room, to move your blood through blood vessels, or to move food through
your intestines. This system includes your skeletal muscles, cardiac muscles (in
your heart), and smooth muscles (part of arteries and veins, bladder, gastroin-
testinal tract, respiratory tract, uterus, and more).
enzyme: Substance that helps • Circulatory system: This system transports hormones, enzymes, nutrients,
catalyze chemical reactions and other chemicals throughout the body. It includes your heart, blood, and
blood vessels.
• Immune system: This system protects against pathogens, tumor cells, and
other foreign invaders. It includes your thymus, lymph nodes, spleen, tonsils,
and other similar organs.
• Digestive system: This system breaks down and absorbs nutrients from food
and drink. It includes your oral cavity, esophagus, stomach, intestines, and the
other organs associated with digestion including the liver, gallbladder, pancre-
as, and bile duct.
• Urinary system: This system produces, stores, and eliminates urine. It in-
cludes your kidneys, ureters, bladder, urethra, and related organs and glands.
While these organ systems have distinct jobs, they also work closely together.
This is important for nutrition coaching.
For instance, if something is out of order in the gastrointestinal tract (say, with a
client who often gets an upset stomach), it’s probably out of order elsewhere (for
instance, in the endocrine system or nervous system). We’ll talk more about this
in later units.
Organs
Organ systems are made up of individual organs. Each organ has at least one spe-
cific job, and often several.
Tissues
Collectively, our tissues make up our organs.
• Epithelial tissues make up our skin.
• Muscle tissues make up our skeletal muscles and heart, and are part of sever-
al other organ systems
Cells
Tissues are made up of large groups of cells.
Cells range in size from about 7 to 300 micrometers. To give you some perspec-
tive, the dot over this letter “i” is about 100 micrometers.
Cells show us how living matter is wonderfully unique in its diversity. For ex-
ample, immune cells can engulf pathogens and destroy them, while muscle cells
have sliding filaments that cause muscle contraction and relaxation. (Fun factoid!
The axon of a motor neuron in the spinal cord can be up to 1 meter long.)
Organelles
Each cell is like a tiny city. Within each cell are organelles, collections of mole- organelle: Component of the
cules / chemicals that have particular jobs, much like different utilities (such as cell that is responsible for a spe-
cific task
power production or waste disposal) within a city.
There are over 24 known organelles. We’ll talk about the most important ones —
such as the endoplasmic reticulum (ER), Golgi apparatus, and mitochondria — in
this textbook.
cytosol: Internal fluid portion of
These organelles do their jobs in a semi-fluid matrix called the cytosol. the cell
Chemicals
Fundamentally, we are a soup of chemicals.
atom: Basic unit of a chemical Chemicals are built from structures of varying sizes, from atoms (smallest), to
element molecules, to macromolecules (largest).
molecule: Group of atoms
bonded together Macromolecules are made up of groupings of molecules. Molecules are made up
of tiny particles called atoms. And these atoms, which are invisible to the naked
macromolecules: A large
molecule eye, make up all material things of the universe.
So if you think about it, nutrition coaching is really about harnessing the funda-
mental particles of everything that exists.
As astronomer Carl Sagan famously said, “The cosmos is also within us. We’re
made of star stuff.”
Our body can only do what it does if our cells, and the organelles within them,
can do what they do: send and receive messages, create proteins, etc. Indeed,
nearly everything that happens in the body is based on making proteins, and
what those proteins do.
Think of the body as a manufacturing plant — that also manufactures itself. The
proteins we make not only break down and rebuild the plant itself, they break
down and rebuild the machines, the workers, the messengers, and lots of other
stuff.
We’ll get more into this idea as the unit progresses. For now, just remember that
every level of human organization depends on the health of important subunits
— our cells — and the proteins they make.
Figure 1.2. DNA inside the nucleus. Wrapped up in chromosomes, our DNA, or genetic code, dictates which proteins are
formed in the body. The nucleus of each cell contains this genetic code. Each person has a unique genetic code that influences how
we respond to ingested foods.
Because of these various and important roles that nutrients have, the food we eat
can fundamentally change how our body works. No wonder nutrition is so critical!
Nutritional individuality
In the previous unit, we looked at why there is no one “best diet.”
One reason is that not everyone responds the same way to the digestion and
absorption of particular foods — or to the uptake of particular nutrients into
the cell. Research suggests that although the basic mechanics are the same, there
are important and intriguing individual differences, which are likely due to our
unique genetic makeups. genetics: Specific, inherited DNA
of an organism, which influences
Each cell in our body houses our genetic code, a series of nucleic acids called what they become, although
environment also plays a key role
DNA, in an organelle called the nucleus. This code, which is unique to each of
in the expression of an organism’s
us, provides cellular instructions for making proteins we need for our structure genetic code
and function.
DNA: Nucleic acids that contain
instructions for heredity
As we all have slightly different genetic profiles, the proteins we make may also
differ. These variations are responsible for our individual responses to the food nucleus: Organelle where ge-
netic material is housed
we eat. See Figure 1.2.
In general, these differences are quite small. All humans share over 99.9% of
gene: A particular sequence in the same genes. You may have even heard that humans and chimpanzees share
DNA or RNA that controls the between 95% and 98% similarity in their DNA, which is also true.
expression of a protein, and, by
extension, influences the charac-
teristics of an organism
In addition, many important genes have been evolutionarily conserved. This
means that those genes appeared very early in our evolutionary history, perhaps
evolutionarily conserved:
Something that’s remained es-
even back in the days of single-celled bacteria.
sentially unchanged throughout
evolution For instance, much of what we know about the health effects of fasting comes
from research on a tiny, primitive flatworm known as Caenorhabditis elegans.
C. elegans has nearly 200 known genes that respond to dietary restriction. These
genes are involved in things like knowing when metabolism is disrupted; looking
for and repairing DNA damage; and hunting for cancer-type overgrowths. We
share 45 of those genes.
genetic polymorphism: However, these small genetic differences, called genetic polymorphisms, explain
Variation in the form of one or a why some people respond slightly differently to various types of foods. These
sequence of genes
differences may also explain why many research studies seem to have confusing
or conflicting conclusions.
• However, in people with the slow enzyme, the caffeine hangs around longer,
causing health problems.
So imagine a study that asks: “Is 1-3 cups of coffee a day healthy or unhealthy?”
For example, isothiocyanates found in broccoli can switch on a gene in the liver
that detoxifies cancer-causing chemicals and other toxins.
Without the broccoli, this gene stays inactive. Our body looks for other detoxifi-
upregulated: An increase of a ers. With the broccoli, this gene is upregulated and participates more actively in
cellular component the detoxification process.
Some of us have this gene, and some don’t. If we don’t have the gene, broccoli
can’t help us fight cancer in this particular way. (Of course, broccoli does other
good things.)
that switch off growth-promoting genes in the prostate. With cooked tomatoes in
the diet, prostate cancer risk decreases; without the tomatoes, risk increases.
Fish oil is yet another example. Fish oil (specifically DHA — a fatty acid found in DHA: Docosahexaenoic acid, an
fish, other marine animals, and fish / algae oil supplements) might signal genes omega-3 fatty acid
in the brain to produce a chemical that preserves brain function with age. People
who consume more omega-3 fats tend to have better cognitive function as they
age, compared with those who consume less.
Thus, nutrition can strongly influence our gene expression. And our genes, in
turn, affect how we respond (or don’t) to a given nutrition plan. This genetic di-
versity and its relationship with nutrition is an emerging area of research called
nutrigenomics: Study of how
nutrigenomics. genes respond to nutritional
intake
Needless to say, there is an important relationship between what we eat and how
our cells function. Throughout this course, this interaction will become clearer.
By the end of this course, you should have a better grasp of how to optimize
health, body composition, and performance by controlling nutrient intake.
However, before we talk more about food, let’s discuss the cell in depth, and in
particular, the main cellular components and organelles.
Parts of cells
To better understand how the food we eat interacts with our body, it’s important
to learn about the structures, chemicals, and organelles within each of our cells.
In this unit, we’ll review the following organelles:
Plasma membrane Golgi apparatus
Mitochondrion Lysosome
Nucleus Peroxisome
Endoplasmic reticulum
These organelles and approximately 17 others (there are about 24 or so in total)
give our cells their structure and function, which are in turn often shaped by our
nutrient intake.
Extracellular space
Hydrophilic
region
Phospholipid
Hydrophobic
region
Hydrophilic
region
Intracellular space
Figure 1.3. Plasma membrane. The plasma membrane is composed of lipids, proteins, cholesterol and other chemicals. The lipid
bilayer has water-loving (hydrophilic) heads and water-fearing (hydrophobic) tails. Substances generally pass through the plasma
membrane via a transmembrane protein.
bond to water-based molecules. On the other hand, the fatty acid “tails” of the
hydrophobic: Lack of affinity for lipid molecules that form the bilayer are hydrophobic (water-fearing) and bond
water best with fat-based molecules.
This dual-purpose membrane creates a boundary that regulates what gets into
and out of cells. See Figure 1.3.
The cell needs to be choosy about what can enter and exit. Thus, most molecules
must enter the cell through one of several membrane proteins. These proteins are
like gates in a fence, allowing only particular molecules to pass through. We’ll
talk more about these cellular proteins later in this unit.
Because of this lipid structure, the types of fats we eat can change how fluid or
flexible the cell membrane can be.
• Too much saturated fat may cause the membrane to be too rigid.
• Too much polyunsaturated fat may cause the membrane to be too fluid.
Because most people eat too many saturated and trans fats, we often need to saturated fat: A fat with no dou-
balance that with getting enough mono- and polyunsaturated fats. We’ll look ble bonds between the individual
carbon atoms of the fatty acid
at this more later on. For now, just remember that fat balance affects how the cell chain
works in important ways.
trans fat: Fat derived from the
partial hydrogenation of vegeta-
Cytosol ble oils
The interior space of the cell is composed of a gel-like solution called cytosol. monounsaturated fat: A fat
with one double bond between
Many organelles, enzymes, salts and other organic molecules, including stored
the carbons in the fatty acid chain
carbohydrates and fats, are suspended and maintained by the cytosol. The body
carries out many of its chemical reactions in this gel-like matrix, including most polyunsaturated fat: A fat
with two or more double bonds
of its enzymatic reactions. Cytosol, together with all the organelles, except the between the carbons in the fatty
nucleus, are called cytoplasm. acid chain
cytoplasm: The protoplasm
The cytosol is rich in stored carbohydrates that can be broken down quickly and
within a cell, excluding the
used to transfer energy. This process is controlled by cytosolic enzymes. nucleus
Exercise and other physical activity creates a demand for more energy. The cell
responds by making more of these enzymes along with storing more carbo-
hydrate and fat for future use. The cell also gets better at breaking down these
carbohydrates for energy. This is especially true in skeletal muscle cells, since this
is where active people need most of their energy.
A key point here for nutrition coaching is that regular exercise and other activity
can powerfully affect cellular makeup, metabolism and function. Activity can fun-
damentally change how the body uses, processes, and stores nutrients. Active bod-
ies will thus respond differently than inactive bodies to the same nutrition plan.
Mitochondria
Mitochondria (plural of mitochondrion) convert nutrients into energy. mitochondria: Organelles that
supply the cells’ energy / ATP
Just like you can’t eat an egg until you crack open its shell (well, at least we don’t (singular: mitochondrion)
recommend it), you can’t use the energy stored in carbohydrates, proteins, and
fats until you break their chemical bonds. Mitochondria convert the energy
released from this process into adenosine triphosphate (or ATP), the energy adenosine triphosphate: ATP,
currency of the cell. source of energy for physiological
reactions
Mitochondria produce most of the body’s energy — about 95% of it. The rest is
produced in other parts of the cell. If mitochondria don’t work well, we don’t
work well. (Or at all.)
Mitochondria make ATP in their inner mitochondrial membranes. The outer mitochondrial membrane:
membrane of the mitochondrion is porous, while the inner membrane is the The double biomembrane sur-
rounding the mitochondrion
main barrier between it and the rest of the cell. The inner membrane contains
folds called cristae, which are studded with the enzymes and structures that help
make ATP.
Since the mitochondria generate power for the cell, more mitochondria means
more energy, and more active cells. Conversely, the more active we are, the more
mitochondria we likely have (and since your heart is beating all day, every day, it
also has plenty of mitochondria to keep pace). More mitochondria means more
total energy production for a muscle.
Nutrition in practice
Your skin color, body size, hair type, and risk of specific illnesses all depend on
how your genes interact with your environment.
For instance, your genes may suggest that you’ll grow to somewhere between
5’5” and 5’8.” But your actual height is an interaction between genes and envi-
ronment. If you grow up malnourished, you won’t ever reach 5’8.”
What we eat early in life (and what our moms eat while they’re pregnant) can
affect our genes and regulate our traits — including the development of diseas-
es, even decades later.
For example, data from the WWII Dutch Famine show that children of under-
nourished mothers had higher risk for cardiovascular disease, obesity, and breast
cancer later in life. (In fact, this “famine memory” can persist for generations,
“remembered” by descendants’ genes.)
• circadian rhythms (such as sleep, shift work, light-dark cycles, and travel
circadian: Any biological process
that recurs naturally on a day- across time zones); and
night cycle
• a host of other factors we probably don’t even know about yet.
If that sounds a little scary, consider it from the opposite perspective: While we
can’t control our genes themselves, we can affect their expression — whether
they’re likely to get “switched on” or off.
If we know more about our own unique risk factors, we might be more likely to
make healthier choices — choices that could improve our genetic expression.
Genetic screening may show us the way to individualized nutrition and exercise
prescriptions. But we’re not quite there yet. Here’s what we know right now.
Stay tuned.
When genetic screening companies are able to more cost-effectively test the
entire genome (again, most only test a part of it) we should have a greater
understanding of gene sequencing and its use in nutrition. Most experts predict
that’ll happen within a few years, as the cost of sequencing the entire genome
drops from $10,000 to $500.
Matrix
Cristae
Outer membrane
Inner membrane
Figure 1.4. Mitochondria. Inside the mitochondria is where energy converts to ATP. The number of mitochondria in a cell is directly
related to the activity of the cell.
Elite athletes usually have a high mitochondrial density. In general, although ROS are a natural part of this reac-
This means they not only build more total mitochondria tion, we don’t want to make too many at once, or have
with training, they also build more mitochondria per them hanging around too long. ROS can cause cellular
unit of muscle mass. This gives them the ATP they need damage, including damaging our DNA.
for high-level performance. Once again, we can see how
regular movement and activity can change the funda- Scientists used to think that the more oxygen we con-
mental structure and function of cells. sumed, the more ROS we’d make. However, we now be-
lieve that mitochondrial efficiency changes this equation.
Having a lot of mitochondria is good, but we also want
• People with less-efficient mitochondria make more
them to be effective. In other words, we want mitochon-
ROS with every unit of ATP they produce.
drial quality as well as quantity. In order to understand
this, let’s look at a little bit of biochemistry. • People with more-efficient mitochondria make fewer
ROS for the same amount of ATP.
When we make ATP for energy, our cells consume
oxygen, and produce reactive oxygen species (ROS) as a So if your mitochondria are efficient, you make lots of
byproduct. Just as with nutrient processing, not every- energy with fewer damaging waste products. You feel
one does this at the same rate. great, you perform well, and you live longer.
Different people may make ATP at different rates. They While there is a genetic component to mitochondrial
may use different amounts of oxygen to do this; they may function, it’s strongly affected by how we live, what we
need different amounts of food energy to do this; and they eat, and what we do.
may produce different amounts of ROS in the process.
See Figure 1.4 for more.
Nutrition in practice
Nutrient deficiencies can affect our mitochondrial function. Statin drugs, de-
pression, fibromyalgia, or Parkinson’s disease are all associated with low levels of
co-enzyme Q10 (CoQ10). We need this compound for energy production in the
mitochondria.
Nucleus
The nucleus, usually found in the central part of the cell, is the largest organelle.
Most cells have only one nucleus, though muscle cells have more than one. The
nucleus is Mission Control, home of our DNA, also known as the genetic code.
Wrapped up in chromosomes, our DNA dictates which proteins are formed in chromosomes: Located in
the body. This ultimately determines everything from how the body develops, the nucleus, contain genetic
information
to how it repairs itself, to how it transports and / or metabolizes every chemical
introduced into circulation. In many ways, our DNA also determines how mus-
cular we can get.
As we’ve discussed, there is an important link between our DNA, our food
intake, and our health. In fact, much of what we eat interacts directly with our transcription: The synthesis of
DNA or causes hormonal cascades that influence our DNA. RNA using a DNA template
These relationships begin in our nucleus: Chemicals can bond with our DNA to translation: Forming a protein
molecule based on the informa-
begin making cellular proteins, processes called transcription and translation. tion contained in the mrna
Rough endoplasmic
reticulum (ER)
Nucleus
protein synthesis: Making proteins, or protein synthesis, takes place using ribonucleic acids
Manufacturing of proteins from (RNA).
amino acids; guided by DNA
ribonucleic acids (RNA): Once these proteins are synthesized in the ribosomes of the rough ER, they move
Various nucleic acids on a single towards the Golgi apparatus. This organelle prepares the newly formed protein
strand containing ribose and molecules that will leave the cell.
uracil, necessary for the control of
cell activities
The Golgi apparatus contains cisternae (tiny disc-like “holding tanks”, similar to
cisterna: Flattened membrane the word “cistern”) that are stacked on one another and small, circular vesicles.
disc of Golgi apparatus (plural:
These vesicles (small sacs) act like little chaperones, engulfing the protein mole-
cisternae)
cules and transporting them to the cell membranes, where they’ll either be sent
vesicles: Fluid filled pouch/ elsewhere into the body, or incorporated into the membrane itself. See Figure 1.5.
sac that can transport and store
compounds
Proteins are thus always being built up and broken down within our cells. This
takes energy and protein for raw materials. If we don’t eat enough, or don’t eat
enough protein, our cells can’t do their jobs of synthesizing and transporting
the proteins we need. Over time, this can lead to problems such as hormonal
imbalances, depressed immune function, or poor recovery from exercise (per-
haps even injuries).
containing enzymes (catalase and oxidase), which also detoxify harmful sub- detoxify: To remove a poison or
stances that enter cells. Found commonly in liver and kidney cells, peroxisomes toxin from the body
are also important in cholesterol synthesis, bile acid synthesis, ß-oxidation, and cholesterol: Synthesized in the
prostaglandin metabolism. liver of humans and other animals.
A precursor of bile acids and ster-
oid hormones
Like mitochondria, peroxisomes are able to break down fats for energy. However,
when they do this, they produce 30-40% more energy as heat but 30% less energy bile: A yellow or orange fluid pro-
as ATP. duced by the liver, concentrated
and stored in the gallbladder, and
released into the small intestine
Since dietary omega-3s increase fat breakdown through peroxisomes, more fat for fat digestion
is burned to do the same daily activities when omega-3 intake is high. Unfor-
ß: Beta, the second letter of greek
tunately, omega-3 supplementation is not a magic fat loss method: The overall
alphabet
impact is minor.
prostaglandin: Class of physi-
ologically active fatty acid com-
Body function pounds present in various tissues;
can have hormone-like effects
Let’s look now at how these cellular components, and the chemicals they make
and use, work together within the body.
Enzymes
Enzymes make up the largest group of proteins in the body. You can often spot
enzymes by their names, which typically end in “-ase”, such as:
• lipase (enzymes that break down lipids);
Enzymes are important biological catalysts, substances that jump-start and catalyst: A substance that accel-
speed up nearly every chemical reaction that occurs in the body. erates a chemical reaction
Enzymes work by exposing their own “active sites” to connect with particular
molecules. Once the enzyme can hold these molecules in place, reactions can lock-and-key model: Model
occur. One model of this process is the lock-and-key model. In this model, the that explains enzyme specificity
Products
Substrate
weakened
substrate bonds
active site
Figure 1.6. Enzymes. Enzymes expose their own “active sites,” connecting with spe-
cific molecules. Holding these molecules in place, they allow reactions to occur, which
allows for product formation.
enzyme and its chemical partner fit together tightly and carry out their reaction.
induced fit model: Model that In another model, the induced fit model, the enzyme and chemical partner
suggests enzymes are rather flex- undergo structural changes when close to one another, eventually fitting together
ible structures
properly and starting the reaction. You can think of this like puzzle pieces that
change their shape when they are near each other.
No matter what model you apply, the key idea is that enzymes must somehow fit
and connect with their chemical partners. Lipase can only work with lipids; it can’t
work with proteins.
Co-enzymes
co-enzyme: Non-protein com- Just like a co-pilot works with a pilot, co-enzymes work with enzymes. Coen-
pound that forms the active por- zymes are non-protein molecules, made up wholly or partly of vitamins. We
tion of an enzyme system need them for enzyme-catalyzed reactions.
catalyze: Initiate or increase the
rate of a chemical reaction For instance, pyridoxal phosphate, the active form of vitamin B6, acts as a co-en-
zyme in all transamination reactions, a particular kind of chemical reaction
involving amino acids. We’ll talk about these types of chemical reactions later in
the text.
And you may already have heard of co-enzyme Q10, which we mentioned earlier,
and which is involved in cellular respiration reactions.
Protein receptors
Protein receptors are found both in the plasma membrane and inside the cell.
As we’ve discussed, cell membranes help control what gets in and out of our
cells. They do this, in part, with membrane protein receptors that act like little
chemical gates.
signal transduction: Cells get information about their outside world by signal transduction. The
Conversion of one signal to an- process is a little bit like the telephone game you played as a kid.
other by a cell
receptor-ligand binding com- A receptor on a cell binds to what is known as a ligand, forming a receptor-ligand
plex: A complex formed between binding complex. A ligand attaches to its specific receptor and no other. The
a receptor and a substance to ligand activates its receptor, which then activates a second messenger inside the
allow for further cellular activity
cell. Then the second messenger activates another second messenger, and so on
ligand: An ion or molecule that until the last second messenger goes into the nucleus and triggers changes in gene
binds to another molecule or
metal atom
expression that leads to some sort of cellular response.
second messenger: Substance An example of this process is our cellular response to insulin.
that mediates intracellular activity
by relaying a signal from an extra- • After we eat, insulin is released from our pancreas and travels through the
cellular molecule bloodstream.
Once bound, this connection signals to proteins inside the cells — usually called
second messengers — to get more channels to the membrane and accept glucose
more readily.
As we’ve stressed already, physical activity changes how our cells respond to
nutrients. Repeated muscular contractions (for instance, 30 minutes of pumping
our legs on a bike) tell the cell to move more protein receptors to the cell mem-
brane. This helps glucose get into the cell more efficiently and effectively to help
refill the fuel tank.
What we eat can also influence second messengers. For instance, caffeine in
coffee / tea, theobromine in cacao, and theophylline in tea / cacao can all inhibit
phophodiesterase, an enzyme that breaks down second messengers in cells. So,
in the case of caffeine, this means stronger / faster heart muscle contractions,
greater blood vessel constriction, and enhanced stomach acid secretions.
Transport proteins
Transport proteins are also involved in cellular communication. These live in
cell membranes and let molecules pass between spaces inside the cells and spaces
outside of cells.
This movement across the plasma membrane can take place via one of two
mechanisms:
• passive transport (which doesn’t need energy), or
Active transport allows vitamins, minerals, glucose, and amino acids into cells. See
Figure 1.7
In the next unit, we’ll look at how some of these chemical processes and cellular
structures and tasks are involved in digestion.
Extracellular space
Intracellular space
Figure 1.7. Transport proteins. Transport proteins specifically allow the passage of
water-soluble molecules between the spaces inside the cells and the spaces outside the
cells. Movement across the plasma membrane can take place via one of two mechanisms:
facilitated diffusion or active transport. Cellular transport allows things like vitamins,
minerals, glucose and amino acids into cells.
Nutrition in practice
Salivary amylase is an enzyme in saliva that starts the digestion of starch. It helps
to improve our “mouth experience” while eating (e.g., enhanced taste of certain
foods). We’ve known about it for over 100 years.
Cell types
In the next unit, you’ll meet some different cell types.
You’ll notice that many types end in the suffix “cyte.” This suffix will tell you that
something is a cell. (For more on this, see the “Language matters” sidebar.)
Each cell’s structure can tell you about its job. For instance:
• Enterocytes, which line the intestine, are shaped like little brushes. This increas-
es their surface area and helps them absorb nutrients.
• Cuboidal, or cube-shaped cells, are found in the salivary glands and the lining
of the mouth. Because of their shape, they tend to be a little stronger and
tougher, so they’re often used as structural cells.
• Squamous cells are flat cells that look a bit like layers of fish scales. They line the
esophagus and help protect it from stomach acid. They’re easily sloughed off
and replaced.
There are many types of cells within the human body. You won’t learn them all.
Just get the general idea: Cells are not only diverse inside, they’re diverse outside
too. Each unique cell type and structure is adapted for a specific job.
Language matters
Many of our English medical terms come from ancient Greek or Latin, or even
older sources. You’ll notice we often mention where these terms come from.
But you may find it helpful to understand where words come from, so that you
can guess at what an unfamiliar word might mean.
For instance:
“Entero” comes from the Greek enteron, or intestine.
“Hepatic” comes from the Greek hepatikos, or liver.
“Gastric” comes from the Greek gaster, or stomach.
“Cyte” comes from the ancient Greek kyto, which refers to a hollow or empty
container. We now use it to refer to cells.
“Epi” comes from the even more ancient Proto-Indo-European epi, meaning near,
at, or against.
So any time you see a form of these words, you’ll know what you’re dealing
with.
For instance, enterocytes are intestinal cells. Hepatocytes are liver cells. Epithelial
cells are cells that are the top layer of something, such as the innermost layer of
the esophagus.
This study of where words come from is known as etymology. This can give us
clues about what those words mean. It can also help you if English is not your
first language.
If you’re having trouble recalling a particular term in this course, try Googling
“etymology” and that term. You might learn a little factoid or two about that
term that helps it stick with you.
Get to know the language of your field and where it comes from, and you’ll
probably find that your understanding and comfort with the terminology im-
proves. (And you’ll remember it better when tested!)
Summary
The trillions of cells of the human body work together as enzymes and co-enzymes, or protein receptors) to
to form tissues, organs, and organ systems. The total of begin and carry out chemical reactions; to send cell
all of the activities taking place in these systems is what signals; and / or to transport other molecules.
most people refer to as “metabolism.”
The food we eat interacts with the small chemical reac-
There are many levels of organization in the body, from tions and processes taking place in our cells.
microscopic atoms up to fully functional organisms (and
beyond, to ecosystems). These systems are interconnect- Food thus affects our health in five ways. It:
ed, and all must work properly for organisms to thrive.
1. provides energy
Our cells have many jobs, including:
2. provides molecules involved in chemical reactions
• converting nutrients into energy (particularly ATP)
3. is incorporated into body structures
• making proteins (under the direction of our DNA)
• moving those proteins, nutrients and other substanc- 4. influences chemicals such as hormones and
es around (including in and out of the cell across the neurotransmitters
membrane) and
5. affects genetic protein-making signals as well as the
• clearing waste and debris from the cell. quality of the proteins that are made
Our cells use specialized structures and molecules (such