Applied Nutrigenomics
Where Genes and Food Come Together
by Dr. John M. Berardi, PhD, CSCS
Nutrigenomics: The study of how genes and nutrients interact. Until
recently, I knew this field of science was an exciting area that would
someday change the future of nutrition, medicine, and more. However,
in my mind all this crazy gene-nutrient stuff was still wrapped up in
mystery. It was the stuff futurists hypothesized about rather than the
stuff physicians, nutritionists, and health experts could use every day.
Six
months ago I was fortunate to sit in on a small-group lecture led by
one of the world's top nutrigenomics researchers, Dr. Ahmed El-Sohemy.
When I heard Dr. El-Sohemy speak, I realized that I was wrong. With the
completion of the human genome project and the latest nutritional
science, it's clear that nutrigenomics is no longer the future of
medicine. It's here
today. And it's being applied by cutting-edge health experts everyday. As
I sat in the audience, my neurons were firing like a fourth of July
light show. There was so much info flying around that my pen couldn't
move fast enough to keep up. I knew I had to sit down to pick Dr
El-Sohemy's brain. Here's what came out of our latest conversation.
John Berardi:
Dr. El-Sohemy, thanks for agreeing to do this interview. It's much
appreciated and I know everyone reading will be fascinated by your work. A
few months back, you presented some very interesting data looking at
how genomic information can impact our understanding of nutrition and
nutrient science. In other words, you talked about how our genes can
determine our responses to the food we eat, the supplements we take,
and more. For those readers unfamiliar with this area of research, can you briefly describe the field of nutrigenomics?
Dr. El-Sohemy Dr. Ahmed El-Sohemy:
Nutrigenomics,
sometimes called nutritional genomics, investigates how the foods we
eat interact with our genes to affect our health. The questions we
typically ask are, "How much of each nutrient should a particular
person consume?" and, "What are the biological effects of a specific
supplement?"
There are basically two approaches that we use to investigate such questions.
First,
we look at how common variations found throughout the human genome
explain individual differences in response to dietary intake. For
example, this area of research explains why some people can eat a high
fat diet and have no problem with their cholesterol levels while others
experience the exact opposite response.
Breakfast of champions for some, heart attack special for others.
This line of research, sometimes referred to as
nutrigenetics, enables us to understand why some individuals respond differently than others to the exact same nutrients.
The
second approach that nutrigenomics researchers use is to investigate
how nutrients and bioactive components in food turn on or off certain
genes — these genes impacting important metabolic and physiologic
processes in the body.
For example, researchers
have identified compounds found in broccoli that switch on a specific
gene that helps the body detoxify some of the harmful chemicals we're
sometimes exposed to.
Of
course, this line of research helps us understand the mechanisms behind
how food, and specific compounds within food, can impact our health. Berardi:
This is really cool stuff, especially since people have long proclaimed
that when it comes to nutrition, "you gotta find what works for you."
Often times this means lots of trial and error. In essence, the field of nutrigenomics is helping to explain
why you gotta find what works for you, as well as helping to determine
whatwill work for your genetic type. Before
getting deeper into your research, I'm curious. How does someone like
you get involved in the field of nutrigenomics? What's your background? Dr. El-Sohemy: I
first became interested in this field about 10 years ago, which is
before the term "nutrigenomics" was actually coined. At the time, I was
working on my PhD in nutritional sciences and was researching the
effects of cholesterol on cancer using rodent models.
One
of my experiments gave totally unexpected results. In fact, they were
completely the opposite of those published by other researchers. It
turned out, however, that the strain of rat that I used metabolizes
cholesterol quite differently than other strains that were used in
previous experiments.
The study design was
virtually identical to previous ones, but the only real difference was
the genetic background of the animals. I realized the importance of
considering genetics when studying nutrition and it occurred to me that
genetic differences between humans could also explain why some people
respond differently than others.
So
I decided to take some genetics courses and complete a major in
molecular biology. After finishing my PhD at the University of Toronto,
I went to Harvard for a fellowship to pursue this type of research in
humans. Berardi: As such, you're
definitely a pioneer in the field. And it's awesome that we have guys
like you with extensive bio and genetics backgrounds looking into some
very important nutritional questions. Just how can our genes impact our personal responses to the foods we eat and the drugs we take? Dr. El-Sohemy: Well,
to start with, we've known for a long time that individuals respond
differently to certain drugs. In fact, much of the pioneering work in
pharmacogenetics was done decades ago at the University of Toronto.
But
the concept of personalized medicine dates as far back as 480 BC when
Hippocrates, the father of modern medicine, noted that "Positive health
requires a knowledge of man's primary constitution and of the powers of
various foods, both those natural to them and those resulting from
human skill."
The
word "constitution" is a clear reference to our genetic profile and the
"foods resulting from human skill" can be seen as the dietary
supplements and functional foods we now have available.
Just
like with drugs, when it comes to the nutrients we take in through our
diets or the supplements we take, our genes can cause us to respond
differently from our neighbors.
Here's an
example: Certain genes can affect the rate of absorption, distribution,
metabolism, or excretion of almost everything we consume. And these
differences can result in extreme variability in how we respond.
The
gene that I mentioned earlier, which can be activated by compounds
found in broccoli, is actually missing in about 20% of the population.
So some people won't benefit from the detoxifying properties of
broccoli, although they probably still benefit from its antioxidant
effects.
Understanding the basis of this
variability will certainly help us do a few things. First, it can help
explain some of the inconsistencies among previous studies that have
linked nutrients, supplements, and other bioactives to a number of
health outcomes. Second, it can help us understand how to eat or which
supplements to use based on our genetic profile.
Berardi:
Indeed, I've read that based on genetic differences, the physiological
response to a certain drug or supplement could be 70-times different at
the same dose between two individuals. While this seems shocking, it
does stand to reason. For example, some people respond to
creatine supplementation with large performance improvements and
increases in lean mass while others have no response. From this, it's
likely that one or more of the steps — absorption, distribution,
metabolism, or excretion — are impacted by their different genotypes,
leading to a wide difference in response. I know you're looking into this very thing with respect to caffeine intake. What's your lab showing?
Dr. El-Sohemy: Last year, we published a study in the
Journal of the American Medical Associationto demonstrate that in some individuals, caffeinated coffee intake
lowered the risk of heart attacks. But in other individuals the same
dose of caffeinated coffee
increased the risk of heart attacks.
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