800.892.4772 • ISSAonline.edu
Nutrition: The Complete Guide
Second Edition
International Sports Sciences Association
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
CERTIFICATION COURSES
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 or: International Sports Sciences Association’s Certified Nutrition Specialist program
10 9 8 7 6 5 4 3 2 1
Copyright © 2018 International Sports Sciences Association.
Published by the International Sports Sciences Association, Carpinteria, CA 93013.
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reserved. No part o this work
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Direct copyright, permissions, reproduction, and publishing inquiries to:
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DISCLAIMER OF WARRANTY
Tis text is informational only. Te 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unpublished sources that represents training, health, and nutrition literature and practice summarized by the author and publisher.
Te 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. Te 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. Tis summary of information from unpublished sources, books, research journals,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
About the Authors
Dr. Berardi has been recognized as one o the top exercise nutrition experts in the
world. He earned a PhD in Exercise Physiology and Nutrient Biochemistry at the
University o Western Ontario, Canada. His work has been published in numerous
textbooks, peer-reviewed academic journals, and countless popular exercise and nutrition books and magazines.
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 proessional sports teams. He is also an advisor to Apple,
Equinox, Nike, and itleist.
Dr. Berardi was recently selected as one o the 20 smartest coaches in the world and
one o the 100 most influential people in fitness.
With a PhD rom York University in oronto and 10 years o university teaching,
Krista Scott-Dixon has over 20 years o experience in research, adult education, curriculum design, and coaching and counseling. In addition, she has spent over 20 years
pursuing sel-education in health and fitness.
Trough writing, coaching, speaking, teaching, and curr iculum developmen
development,
t, Krista
has galvanized thousands o clients to transorm their health and fitness or the better,
and is guiding a new generation o fitness proessionals to a higher level o success and
satisaction.
Krista is the author o several books, dozens o popular articles, and many academic
publications. She also inspires readers at her groundbreaking women’s weight training
website, Stumptuous.com.
Ryan Andrews is a world-leading educator in the fields o exercise science and
nutrition.
Ryan is a Registered Dietitian with two master’s degrees. He completed his education
in exercise and nutrition at the University o Northern Colorado, Kent State University, and Johns Hopkins Medicine.
A highly respected coach who has been a part o the Precision Nutrition team since
2007, Ryan’s body o work includes an impressive number o articles, presentations,
books, and certification manuals on the topics o eating, exercise and health.
A nationally ranked competitive bodybuilder rom 1996-2001, and now a certified
yoga instructor, Ryan is also an active volunteer with non-profit organizations to help
promote a sustainable uture.
International
Internatio
nal Sports Sciences Association
iv |
Brian St. Pierre is a renowned expert in perormance nutrition.
Brian is a Registered Dietitian with a Masters in Food Science and Human Nutrition
rom the University o Maine. He is also a certified strength and conditioning specialist, a certified sports nutritionist, and the author o five books including the High
Perormance Handbook Nutrition Guide.
As Precision Nutrition’s Director o Perormance Nutrition, Brian contributes to
ground-breaking research, education and curriculum development at PN, where he is
also an esteemed coach.
Brian shares his expertise on a global scale by presenting at conerences around the
world, serving as a nutrition consultant or pro sports teams such as the San Antonio
Spurs, Brooklyn Nets, and Cleveland Browns, coaching proessional and Olympic
athletes, and writing or popular publications including Precision Nutrition.
Camille DePutte
DePutterr is an author, speaker, and communications consultant with a rich
portolio o experience in marketing, public relations, and storytelling.
Camille received her HBA in English rom the University o oronto and trained at
the Humber School or 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 o top brands and business leaders refine
their messaging and improve their customer relationships. Her work has been published extensively in popular websites, magazines and newspapers.
Camille writes or the Precision Nutrition Encyclopedia o Food and is a requent contributor to the Precision Nutrition blog. She is also the author o the workbook Share
Your Story, and sel-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 rom York University, specializing in the area
o muscle development and regeneration, and a Master’s degree in Exercise Physiology
and Biochemistry rom the University o Waterloo. She has also held research positions at some o the most prestigious institutions in the world, including John Hopkins University and oronto’s Hospital or Sick Children.
Outside the lab, Helen has played and coached varsity soccer, and has been involved
in fitness and weight training or almost two decades. She also has two daughters with
whom she wants to share her joy o inquiry and experimentation, but above all, she
wants to teach them resilience, bravery, and grit.
Nutrition: The Complete Guide
How to Use This Text | v
How to Use This Text
When aced with new inormation, students usually wonder one thing:
“Will I ever need to know this in the real world?”
Whether it’s the cosine o an angle, Kepler’s laws o planetary motion, or the enzyme
responsible or orming citrate, students’ most common questions about what they ’re
learning are:
“Will this be on the test?”
“Will I ever need to know this again in my lie?”
We, the authors, know these questions well. We’ve asked them ourselves, most ofen
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 or NASA, you can probably orget Kepler. And the Krebs cycle? Well, you
won’t need that unless you teach biochemistry.
So why learn all this information?
Well, most o us don’t know what we want to be when we grow up. Work (and lie) is
ull o surprises.
You never know what career path you’ll ollow, or what hobbies you’ll take up.
Be prepared for anything. Learn as much oundational knowledge as possible. Now
you have options.
But there’s another, more inspiring, reason or learning this stuff.
It’s actually kinda interesting. It helps explain your world. And makes you super-un at
parties.
In act, when you really dig into this knowledge, you might just change what you want
to do or a living because o it.
What this means
In this program, we’ll provide a lot o oundational knowledge.
We give you more details below.
Tis oundational knowledge — about stuff like cells, digestion, metabolism and
whatnot — can eel a little heavy at times. Especially i you’re new to this material. Or
you’re a practical, hands-on kind o person who would rather spend more time doing
than reading.
Hang in there.
International Sports Sciences Association
vi |
Te payoff comes in the second section, where that oundational inormation gets
applied.
We’ll give you case studies. Strategies or working with real-world clients. Questionnaires and assessments to use with your clients. Psychological strategies or getting
clients excited about working with you. And all kinds o other un things.
Even i 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 rom a client.
By the end o this course, we expect you to understand:
•
how the body works;
•
how to apply that knowledge to working with clients;
•
how to assess, monitor, and revise client programs;
•
how to communicate your knowledge effectively; and
•
how to get your clients on board with your nutrition plans and programs — hopefully feeling just as inspired as you about making progress and changing their nutrition
habits.
How the program is organized
Tis course is split up into two units.
Section 1: Nutrition science
In Section 1, we’ll go through all the nutrition inormation you’ll need to know, such
as:
•
How and why your cells work the way they do
•
How carbohydrate s, 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
Section 2: Nutritional practice
In Section 2, we’ll introduce you to how to coach, including:
Nutrition: The Complete Guide
•
What it means to be a good coach
•
How to prepare for clients
•
How to interact with different clients
•
How to assess clients
•
How to know which approaches are best for which clients
•
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
How to Use This Text | vii
Other learning tools
Troughout the textbook, look or things like:
Unit objectives
Each unit contains clear objectives at the beginning. Tis will tell you what to ocus
on, and give you goals beore you even start reading.
Unit summaries
At the end o each unit, we’ll summarize the most important points rom that unit.
Tese will confirm that you’ve learned what really matters, and give you another handy
tool or review.
Key terms
Te first time a key term appears in the text, it is highlighted and a definition provided
in the margin. Familiarize yoursel with each key term.
Case studies
Most units end with relevant case studies. Tese give you “real-lie” examples o applied 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 o reerences used to create this course. I you’re
interested in learning more about nutrition and health, you can look up and read more
o this primary source literature.
How to focus your learning
Just like coaching or training, learning should be ocused and systematic, with a clear
purpose.
Here are some ways to stay on track and on target with your Level 1 journey.
Learn what you need to learn
You know your own learning style. (And i you don’t, now’s a great time to discover it.)
Help yoursel succeed by building a system that suits you.
Use as many ways o processing the material as possible: reading, writing, thinking
and reflecting, listening, watching, talking about the material, drawing maps and
flowcharts o ideas, etc.
We suggest…
International Sports Sciences Association
Nutrition: The Big Picture | 7
oo 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 orm on vessels and blood pressure can go up. We risk
getting many chronic diseases.
Good nutrition helps control energy balance. We don’t eat too much or too little.
We can stay healthy, fit and strong. We eel good, and our body shows it.
Chronic diseases: A long-acting
disease that does not quickly
resolve, e.g., cardiovascular
disease, cancers, chronic
respiratory diseases and diabetes
Good nutrition gives us nutrients.
Each ood has a certain nutrient density, or nutrients per amount o ood. Since
we want to eat the right amount o ood or our needs, we want to make sure that
that ood is loaded with nutrients.
Imagine several plates, each one ull o one type o ood:
•
a plate of kale
•
a plate of lentils
•
a plate of cookies
•
a plate of salmon
•
a plate of berrie s
•
a plate of saltine crackers
Now, per plate o ood, ask:
•
How many calories are in each plate?
•
How many nutrient s are in each plate?
In some cases, like the cookies, there are lots o calories but ew nutrients. Tat’s
called low nutrient density.
On the other hand, with the kale, there are lots o nutrients but ew calories.
Tat’s called high nutrient density.
We need nutrients to live, and to thrive. Nutrients help us be as healthy as possible, perorm at our best, and live long, active and vibrant lives.
Good nutrition helps us balance energy intake and getting enough o these
valuable, essential nutrients.
Table I.1: High- versus low-nutrient-density foods
Higher nutrient density
Lower Nutrient Density
Bright or deeply colored vegetables
Potato chips
Bright or deeply colored fruits
Soda and fruit juices
Beans, meats, eggs
Hot dogs, deli meats
Whole grains
Refined grains/flours, pastries
International Sports Sciences Association
8 | Introduction
Good nutrition helps us look, feel,
and perform our best.
Good nutrition — and good nutrition coaching — helps
our clients do what is most important to them, without
other things getting out o balance.
Performance
An athletic client might be ocused mostly on perormance. You can also help them stay healthy and strong
as they train. Or to be the right weight (or body at
percentage) or their sport.
Health
Body Composition
An older client might want to simply live healthier and
better. You can also help them keep the bone and muscle
that will keep them active and mobile.
A client who dreams o looking good at the beach or at a
big event (such as a wedding) might want to lose weight.
You can also help them prevent chronic diseases.
Good nutrition is about helping people look better. Feel
better. Perorm better. Live better. And just be better
overall.
As a nutrition coach, take a holistic approach. Help your
clients balance specific goals with general benefits —
perhaps even benefits they didn’t realize were possible.
Good nutrition is outcome-based.
Every nutrition choice you make will lead to an outcome. Tose outcomes can be measured. And they’re a
great mirror o reality.
Tat’s why we love the question “How’s that working or
you?”
Whenever someone tells us they eat really “healthy” —
which is just a concept in their head — the best ollow-up is “Great! How’s that working or you?”
We use this question because it tests perception
against reality. I someone thinks t hey’re eating really
“hea lthy”, but they just don’t have the body, health,
or perormance that could be expected, maybe that
person’s idea o “he althy” doesn’t match reality. Maybe
they’re not making outcome-based decisions.
Indeed, lots o people in North America think they have
a really healthy and ba lanced diet.
Yet, or example:
Nutrition: The Complete Guide
Figure I.1 Good nutrition resides in the intersection between
health, performance, and body composition.
•
A study of Canadians found that over 60% of the calories they eat come from highly processed foods.
•
In the US, just over 11% of calories come from fast
food.
•
That “5 servings a day of fruit and vegetables” habit?
Data show that only 30% of people in the UK are doing it… and only 8% of Australians. (And often, those
vegetable servings are potatoes.)
•
Over 90% of clients report eating at least one meal in
a cafeteria or restaurant a day. While some people are
undoubtedly making healthy, less-processed choices
when they eat out, many folks are probably not.
Tat’s why good nutrition includes using outcomes (data
and reality) to inorm uture decisions.
Good nutrition is sustainable for
both us and the planet.
Can we keep eating and producing ood the way we are
now? For how long?
Research suggests that we waste between 30 and 50% o
all ood produced.
Nutrition: The Big Picture | 9
Food ofen travels thousands o miles between the arm and our dinner plate.
While global ood production has gone up, hunger and malnutrition are still big
problems worldwide. And more crops than ever beore are being grown to eed
livestock (not people).
With a planet that isn’t growing and a population that is, our ood decisions need
to be more sustainable and environmentally considerate than ever beore.
Luckily, what helps the planet usually helps our body and hea lth as well. Tat’s why
good nutrition is about finding a diet that is sustainable or us and the planet.
Good nutrition is about removing limiting factors.
I you can help your clients identiy their limiting actors — the things that stand
between them and reaching their goals — you’ll become a great nutrition coach.
While you’re building up your expertise, here’s a quick list o possible limiting
actors to look or. (We’ll share more examples later on.)
Genetics and epigenetics
Genetics (the blueprints o our body) and epigenetics (actors that control how
our genes are expressed) can affect how your clients respond to nutrition.
For example:
•
Few clients will have the genetic makeup to reach the upper limits of human
performance.
•
Some clients will have genetic factors that can make losing weight, gaining
Epigenetics: The study of
changes in organisms caused by
modification of gene expression
rather than alteration of the
genetic code itself
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.
Genes are not destiny. Epigenetic actors — such as nutrition, stress, or a healthy
environment — can strongly affect genetic expression. So you might carry several o the known gene variants or obesity… but you can also choose what to eat
or dinner, or put on running shoes and get outside.
Almost everyone can make daily choices that will keep them as healthy, fit, and
vibrant as possible, or their i ndividual body.
Exercise
Amino acids: The building
blocks of protein. Organic
compounds containing both
COOH and NH2
Gene variants: Diversity in gene
sequence within a population
or among populations that are
most commonly due to single
nucleotide polymorphisms (SNPs)
or copy number variant s (CNVs)
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 a nd unfit people.
So exercise (or lack thereo) can be an important limiting actor.
International Sports Sciences Association
12 | Introduction
•
Nutrition knowledge and diet history: Some
clients will be devout followers of a certain dietary
practice, or a history of trying dif ferent diets. Others
have very little nutrition knowledge at all.
•
Time: Some clients have an open schedule, ready for
any kind of health and fitness project. Others have
a crowded daily schedule and countless conflicting
priorities.
•
Ethnic background and heritage: Our coaches
practice all over the world. Our clients live, and come
from, all over the world. A meal or cuisine that suits
an Anglo family may not suit their Hispanic, Somali,
or Punjabi neighbors. A client from a northern European ethnic group may digest dairy easily, while the
client of Japanese heritage next to them may not.
•
Age: As we age, our metabolisms change, our food
tolerances and appetites change, and our digestive
abilities change.
You get the picture.
•
“real-life” testing and client experience.
Good coaches stay skeptical, think critically, and take a
broad perspective.
Indeed, here’s one crucial piece o evidence:
The healthiest people in the world
don’t have a single nutrition
philosophy.
Physiologically, the human body can do well under all
kinds o different nutritional conditions.
We can see this clearly i we look at the traditional diets
o indigenous groups and ethnic groups throughout the
world.
•
For example, the Arctic Inuit and African Masai eat
traditional diets that are high in fat and animal products, with few vegetables.
•
Conversely, Kitavans in the South Pacific, the Hadza
of East Africa, and many groups in the Amazon basin
(such as the Tsimane of Bolivia) eat traditional diets
that are low in fat but high in vegetables and starchy
As a nutrition coach, your job is to help your clients — as
unique people — get to their goals. o do what matters
to them, in the way that’s best or them.
carbohydrates.
The best coaches don’t have a single
nutrition philosophy.
•
The !Kung of Africa eat traditional diets that are made
up of mostly nuts and seeds.
You might have the approach you like, or one that
worked or you. Great. Tat’s a solid start.
Tis is also true i we look at the world’s Blue Zones,
areas where people live exceptionally long and healthy
lives.
But good coaches take a flexible approach. Tey borrow
the best ideas rom everywhere and everyone, and are
always looking or new insights or tools. Tey don’t get
stuck in dogma.
You probably wouldn’t mistake Okinawan cuisine or
the Mediterranean cuisine o Sardinia, Italy or Ikaria,
Greece. Or the Central American cuisine o Costa Rica’s
Nicoya peninsula.
The best coaches use data and
evidence to make decisions.
Tese cuisines and dietary patterns differ.
Troughout this course, we’ll encourage you to wear
your scientist hat and gather data or outcome-based
decision making.
Good coaches look at the evidence. Tis can include:
•
peer-reviewed clinical and scientific research;
•
understanding the basis of how and why things work
(or don’t); and
Nutrition: The Complete Guide
Yet people eating these ancestral or traditional diets have
much ewer o the chronic “diseases o affluence” (such
as cardiovascular disease, stroke, diabetes, obesity, etc.)
considered normal in industrialized areas.
The human body adapts amazingly
well to many different ways
of eating.
You can be healthy and fit whether you eat mostly meat
Nutrition: The Big Picture | 13
or mostly veggies, mostly at or mostly carbohydrates , many times a day or just a
ew times, and so on.
Carbohydrates: A group of
compounds including sugars,
starch, and cellulose
Which means that, as a nutrition coach, you shouldn’t really belong to any specific 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.
•
Be humble and open-minded enough to let yourself be wrong, even if you
really like being right. (Which we do.)
Don’t ocus on the ood itsel. Or on making sure everyone ollows your “nutrition rules.”
Focus instead on your clients. What do they need to be their best?
Good nutrition is more similar than different.
You might be wondering: How can such varied diets all keep people fit and
healthy? Well, despite their disparities, most effective nutrition programs are
more alike than different.
1. Good nutrition asks people to care about their food
and eating.
Research shows that your actual choices are probably less important than simply
paying better attention to what you eat .
When you really care about what you eat, and make mindul, deliberate choices,
you almost inevitably eat better.
2. Good nutrition focuses on food quality.
Almost no decent diet plan asks you to eat more processed, nutrient-depleted
pseudo-ood.
Instead, pretty much every camp recommends eating whole, minimally processed, nutrient-rich oods — oods with which our body has a longstanding
relationship.
Regardless o the macronutrient breakdowns or specific choices, just eating better quality ood will improve most people’s health significantly.
3. Good nutrition helps eliminate nutrient deficiencies.
When we care about what we eat, choose oods mindully, and try to get the
best-quality oods we can afford, we usually get lots o valuable nutrients along
or the ride.
Ofen, when people start a certain diet program, they just start eating better
International Sports Sciences Association
14 | Introduction
overall. Tey get more nutrients. Tey may get more variety. Or resher oods. Or
less-processed oods. Or oods they chose mindully.
Because o these actors, they eel better. And that’s one reason they start making
wild claims about the rejuvenating power o their new diet.
Tey didn’t do anything special, real ly. Tey ofen just started getting what their
bodies needed.
4. Good nutrition helps control appetite and food intake.
Hyper-palatable: Foods that
are exceptionally pleasing to the
sense of taste.
For most people, “it’s hard to eat just one” o the hyper-palatable deliciousness
bombs o processed oods. We ofen keep eating and eating them, but don’t eel
satisfied.
We may also eat them on the go, when we’re rushed and busy. So not only are we
eating oods that encourage us to eat more o them, we’re not even really paying
attention to the experience at all.
Conversely, when we’re more aware o what we’re eating; choose a variety o
more satisying, higher-quality oods; and eliminate nutrient deficiencies, we
almost always end up eating less ood overall.
We eel more satisfied — both physiologically and psychologically. We lose at,
gain muscle, and perorm better.
Notice that you don’t need calorie counting here. Focusing on ood awareness
and ood quality is usually enough or people to tune into their own hunger and
appetite. Tat 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) orever.
5. Good nutrition promotes regular exercise.
When people start paying attention to their eating, they usually star t thinking
about physical activity too. Or vice versa: I you take up an activity you love,
eventually you start wondering i your nutrition could help you do that activity
better.
Good nutrition fits with regular activity like a key into a lock.
And most nutrition programs suggest that people exercise along with eating well.
What this means for you as a nutrition coach
Stay open-minded and flexible. Question everything.
Learn more about global nutrition and eating habits. Broaden your ocus.
Expand your world. (I possible, travel and actually experience different oods,
cuisines, and ood philosophies.)
est your theories and programs. See how they work on actual clients with real
lives and real bodies in the real world. Look or evidence. Gather data and measure outcomes.
Nutrition: The Complete Guide
Cells | 25
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,
hydrogen and oxygen, are
the basic units of matter.
Example: carbon.
G. Organ System
Organs work together to form
organ systems.
Example: circulatory system.
H. Complex Organism
Organ systems sustain
complex organisms.
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 or our cells to work properly. Tis means getting the right nutrients in the right
amounts.
And the body lives within even larger systems.
When we eat well, our cells unction well. When we
don’t eat well, problems happen.
Our body lives within ecosystems — dynamic, interactive, interconnected networks o living things.
Healthy cells means healthy metabolism. Unhealthy cells
means un healthy metabolism.
Some scientists even think that given how many bacteria
are on us and in us, humans aren’t even really “separate”
bodies at all!
How the body is organized
Organism
Cells — and by extension, the body — is organized into
systems, each system nested into another. See Figure 1.1.
Te organism is, well, you.
Ecosystem
An organism is a definably sel-contained living system.
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For the purpose o this program, we can say that you as a human are a distinct
organism. (Bacterial buddies notwithstanding.)
homeostasis: The body’s ability
to maintain a stable and constant
internal condition
As an organism, the human body can reproduce, replace, and repair itsel, all to
stay alive and to maintain homeostasis : the state o balanced unction in the body.
Organ systems
Complex organisms, such as humans, are made up o 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 intestine s. This system includ es your skeletal muscles, card iac muscles (in
your heart), and smooth muscles (par t of arterie s and veins, bladder, gastrointestinal tract, respiratory trac t, uterus, and more).
•
Nervous system: This system sends electrochemical signals that trigger
thoughts, emotions, and movement as well as involuntary activity (such as
breathing). It includes your brain as well as a vast network of nerves and supporting structures.
•
Endocrine system: This is your cellular communication system. It includes
your hormonal organs and glands, including the hypothalamus, p ineal gland,
pituitary gland, thyroid gland, liver, pancreas, kidney, adrenal glands, testes,
ovaries, and more.
enzyme: Substance that helps
catalyze chemical reactions
•
Circulatory system: This system transports hormones, enzymes, nutrients,
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.
•
Respiratory system: This system brings in oxygen and excretes carbon
dioxide. It includes your nasal cavity, trachea, lungs, and other airways and gas
exchange 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, pancreas, 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.
•
Reproductive system: This system controls reproduction as well as sexual
development. It includes your sex organs and glands.
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Cells | 27
While these organ systems have distinct jobs, they also work closely together.
Tis is important or nutrition coaching.
For instance, i something is out o order in the gastrointestinal tract (say, with a
client who ofen gets an upset stomach), it’s probably out o order elsewhere (or
instance, in the endocrine system or nervous system). We’ll talk more about this
in later units.
Organs
Organ systems are made up o individual organs. Each organ has at least one specific job, and ofen several.
Tissues
Collectively, our tissues make up our organs.
•
Epithelial tissues make up our skin.
•
Connective tissues make up structures such as our joints and fascia.
•
Muscle tissues make up our skeletal muscles and heart, and are part of sever-
al other organ systems
Nervous tissues make up our brain, ner ves, and associated structures.
Our tissues do many things, such as:
•
form protective barriers against outside invaders (epithelial tissues);
•
hold us together (connective tissues);
•
move the body around (skeletal muscle tissues); or
•
communicate between cells (nervous tissues).
Cells
issues are made up o large groups o cells.
Cells range in size rom about 7 to 300 micrometers. o give you some perspective, the dot over this letter “i” is about 100 micrometers.
Cells show us how living matter is wonderully unique in its diversity. For example, immune cells can engul pathogens and destroy them, while muscle cells
have sliding filaments that cause muscle contraction and relaxation. (Fun actoid!
Te axon o 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 o molecules / chemicals that have particular jobs, much like different utilities (such as
power production or waste disposal) within a city.
organelle: Component of the
cell that is responsible for a specific task
Tere 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.
Tese organelles do their jobs in a semi-fluid matrix called the cytosol.
cytosol: Internal fluid portion of
the cell
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Rough endoplasmic
reticulum (ER)
Nucleus
Transport vesicle
from ER
Cis (C) face:
receives transport
vesicles from ER
Golgi apparatus
Transport vesicle
from Golgi apparatus
Trans (T) face: produces
vesicles for cellular
use or for excretion
Figure 1.5. Endoplasmic reticulum and Golgi apparatus
protein synthesis:
Manufacturing of proteins from
amino acids; guided by DNA
Making proteins, or protein synthesis , takes place using ribonucleic acids
(RNA).
ribonucleic acids (RNA):
Various nuclei c acids on a single
strand containing ribose and
uracil, necessary for the control of
cell activities
Once these proteins are synthesized in the ribosomes o the rough ER, they move
towards the Golgi apparatus. Tis organelle prepares the newly ormed protein
molecules that will leave the cell.
cisterna: Flattened membrane
disc of Golgi apparatus (plural:
cisternae)
vesicles: Fluid filled pouch/
sac that can transport and s tore
compounds
Te Golgi apparatus contains cisternae (tiny disc-like “holding tanks”, similar to
the word “cistern”) that are stacked on one another and small, circular vesicles.
Tese vesicles (small sacs) act like little chaperones, engulfing the protein molecules and tra nsporting them to the cell membranes, where they’ll either be sent
elsewhere into the body, or incorporated into the membrane itsel. See Figure 1.5.
Proteins are thus always being built up and broken down within our cells. Tis
takes energ y and protein or raw materia ls. I we don’t eat enough, or don’t eat
enough protein, our cells can’t do their jobs o synthesizing and transporting
the proteins we need. Over time, t his can lead to problems such as hormonal
imbalances, depressed immune unction, or poor recovery rom exercise (perhaps even i njuries).
Lysosomes and peroxisomes
lysosome: Organelle containing
hydrolytic enzymes
microorganism: Organism of
microscopic size
peroxisome: Cytoplasmic organelle with enzymes that help with
the breakdown of fatty acids and
other macromolecules
Nutrition: The Complete Guide
Lysosomes are the “garbage disposal units” o our cells. Tey are vesicles, containing more than 50 different enzymes, which can break down cellular components and protect cells. I a large molecule, such as an old cellular structure
or a microorganism , enters the cell, the lysosome will engul it then digest and
dispose o it. By keeping the cells clear o waste and debris, lysosomes help renew
and protect the cell.
Peroxisomes are similar to lysosomes: they are small membranous sacs
Cells | 39
containing enzymes (catalase and oxidase), which also detoxify harmul substances that enter cells. Found commonly in liver and kidney cells, peroxisomes
are also important in cholesterol synthesis, bile acid synthesis, ß-oxidation, and
prostaglandin metabolism.
Like mitochondria, peroxisomes are able to break down ats or energy. However,
when they do this, they produce 30-40% more energy as heat but 30% less energy
as AP.
Since dietary omega-3s increase at breakdown through peroxisomes, more at
is burned to do the same daily activities when omega-3 intake is high. Unortunately, omega-3 supplementation is not a magic at loss method: Te overall
impact is minor.
Body function
detoxify: To remove a poison or
toxin from the body
cholesterol: Synthesized in the
liver of humans and other animals.
A precursor of bile acids and steroid hormones
bile: A yellow or orange fluid produced by t he liver, concentrated
and stored in the gallbladder, and
released into the small intestine
for fat digestion
ß: Beta, the second letter of greek
alphabet
prostaglandin: Class of physiologically active fatty acid compounds 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 o proteins in the body. You can ofen spot
enzymes by their names, which typically end in “-ase”, such as:
•
lipase (enzymes that break down lipids);
•
protease (enzymes that break down proteins); or
•
amylase (enzymes that break down carbohydrates).
Enzymes a re important biological catalysts, substances that jump-start and
speed up nearly every chemical reaction that occurs in the body.
catalyst: A substance that accelerates 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
occur. One model o this process is the lock-and-key model. In this model, the
lock-and-key model: Model
that explains enzyme specificity
Products
Substrate
weakened
substrate bonds
active site
Enzyme
Enzyme-Substrate
Enzyme
Figure 1.6. Enzymes. Enzymes expose their own “active sites,” connecting with specific molecules. Holding these molecules in place, they allow reactions to occur, which
allows for product formation.
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induced fit model: Model that
suggests enzymes are rather flexible structures
enzyme and its chemical partner fit together tightly and carr y out their reaction.
In another model, the induced fit model, the enzyme and chemical partner
undergo structural changes when close to one another, eventually fitting together
properly and starting the reaction. You can think o 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.
See Figure 1.6.
Many environmental, genetic, and nutritional actors — including temperature,
pH, substrate concentration, and vitamin and mineral status — influence how enzymes work. Tus, nutrition plays an important role in most enzymatic reactions.
Co-enzymes
co-enzyme: Non-protein compound that forms the active portion of an enzyme system
catalyze: Initiate or increase the
rate of a chemical reaction
Just like a co-pilot works with a pilot, co-enzymes work with enzymes. Coenzymes are non-protein molecules, made up wholly or partly o vitamins. We
need them or enzyme-catalyzed reactions.
For instance, pyridoxal phosphate, the active orm o vitamin B 6, acts as a co-enzyme in a ll transamination reactions, a particular k ind o chemical reaction
involving amino acids. We’ll talk about these types o chemical reactions later in
the text.
And you may already have heard o co-enzyme Q10, which we mentioned earlier,
and which is involved in cellular respiration reactions.
Protein receptors
Protein receptors are ound both in the plasma membrane and inside the cell.
As we’ve discussed, cell membranes help control what gets in and out o our
cells. Tey do this, in part, with membrane protein receptors that act like little
chemical gates.
signal transduction:
Conversion of one signal to another by a cell
Cells get inormation about their outside world by signal transduction. Te
process is a little bit like the telephone game you played as a kid.
receptor-ligand binding complex: A complex formed between
a receptor and a substance to
allow for further cellular activity
A receptor on a cell binds to what is known as a ligand, orming a receptor-ligand
binding complex. A ligand attaches to its specific receptor and no other. Te
ligand activates its receptor, which then activates a second messenger inside the
cell. Ten the second messenger activates another second messenger, and so on
until the last second messenger goes into the nucleus and triggers changes in gene
expression that leads to some sort o cellular response.
ligand: An ion or molecule that
binds to another molecule or
metal atom
second messenger: Substance
that mediates intracellular activity
by relaying a signal from an extracellular molecule
An example o this process is our cellular response to insulin.
•
After we eat, insulin is released from our pancreas and travels through the
bloodstream.
•
From there, it can bind to specific, insulin-friendly protein receptors on the
membrane of our cells.
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Cells | 41
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 (or instance, 30 minutes o pumping
our legs on a bike) tell the cell to move more protein receptors to the cell membrane. Tis helps glucose get into the cell more efficiently and effectively to help
refill the uel tank.
What we eat can also influence second messengers. For instance, c affeine in
coffee / tea, theobromine in cacao, and theophylline in tea / cacao can a ll inhibit
phophodiesterase, an enzyme that breaks down second messengers in cells. So,
in the case o caffeine, this means stronger / aster heart muscle contractions,
greater blood vessel constriction, and enhanced stomach acid secretions.
Transport proteins
ransport proteins are also involved in cellular communication. Tese live in
cell membranes and let molecules pass between spaces inside the cells and spaces
outside o cells.
Tis movement across the plasma membrane can take place via one o two
mechanisms:
•
passive transpor t (which doesn’t need energy), or
•
active transpor t (which needs energy).
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 o these chemical processes and cellular
structures and tasks are involved in digestion.
Extracellular space
Intracellular space
Figure 1.7. Transport protei ns. 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 ac tive transport. Cellular transport allows things like vitamins,
minerals, glucose and amino acids into cells.
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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.
Just recently, researchers found a correlation between obesity and a person’s
ability to make amylase. People with fewer AMY1 genes — thanks to genetic
polymorphisms — might not tolerate carbohydrates as well. People whose
ancestors traditionally ate diets higher in starch seem to have more AMY1. This
is another example of the interaction between our environment, culture, genes,
and optimal dietary choices.
Cell types
In the next unit, you’ll meet some different cell types.
You’ll notice that many types end in the suffix “cyte.” Tis 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:
•
Enterocy tes, which line the intestine, are shaped like little brushes. This increases their surface area and helps them absorb nutrients.
columnar epithelial cells:
Pillar-shaped cells that line many
surfaces of the body
goblet cells: Mucus-secreting
epithelial cell that distends, taking
on the form of a goblet; found
often in respiratory and intestinal
tracts
•
Much of the gastrointestinal tract is lined with columnar epithelial cells.
These are tall skinny cells.
•
If their job is to absorb nutrients, there’s only one layer of them.
•
If their job is to secrete things (like saliva), they’re stacked on top of each other
like cases of beer. Stacked cells are known as stratified cells.
•
Some columnar epithelial cells are known as goblet cells because of their
shape.
•
Cuboidal, or cube-shape d 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.
•
The structure of myocytes, or muscle cells, allows them to produce force in
order to move our body around.
Tere are many types o 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 or a specific job.
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Cells | 43
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.
Obviously, you don’t have to brush up on the classics to become a nutrition
coach.
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 refe r 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 improves. (And you’ll remember it better when tested!)
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Summary
Te trillions o cells o the human body work together
to orm tissues, organs, and organ systems. Te total o
all o the activities taking place in these systems is what
most people reer to as “metabolism.”
Tere are many levels o organization in the body, rom
microscopic atoms up to ully unctional organisms (and
beyond, to ecosystems). Tese systems are interconnected, and all must work properly or organisms to thrive.
Our cells have many jobs, including:
•
converting nutrient s into energy (part icularly ATP)
•
making proteins (under the direction of our DNA)
•
moving those proteins, nutrient s and other substances around (including in and out of the cell across the
membrane) and
•
clearing waste and debris from the cell.
Our cells use specialized structures and molecules (such
Nutrition: The Complete Guide
as enzymes and co-enzymes, or protein receptors) to
begin and carr y out chemical reactions; to send cell
signals; and / or to transport other molecules.
Te ood we eat interacts with the small chemical reactions and processes taking place in our cells.
Food thus affects our health in five ways. It:
1.
provides energy
2.
provides molecules involved in chemical reactions
3.
is incorporated into body structures
4.
influences chemicals such as hormones and
neurotransmitters
5.
affec ts genetic protein-mak ing signals as well as the
quality of the proteins that are made