What Is Nutrigenomics and Nutrigenetics and How Do They Affect Your Diet?
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Nutrigenomics and nutrigenetics are two red hot areas of scientific research that simply look at the relationship between your diet and your DNA. Foods completely tailored to my unique body? Yes, please! While it may seem like something out of a sci-fi movie, researchers have made great strides over the past two decades, ever since nutrigenomics and nutrigenetics have been a “thing” in the scientific community. Now, let’s get real for a second. Scientists are not there yet; there is still a wealth of discoveries to be made. But it is a very real, very promising field that has already presented some interesting and useful findings. And I feel extremely lucky to have been one of the pioneer scientists in the field, back when it was simply called just looking at how nutrients interact with genes.
Back then (meaning the early 2000s), we used molecular biology, a field not all that associated with nutrition at the time, to assess how nutrients and other food components directly impacted DNA and vice versa. In fact, my entire PhD dissertation focused on how soy isoflavones (special food components found in soybeans and soy foods) can enter cells and interact with DNA to influence fat burning and fat storage. In essence, for that study, we were ultimately trying to figure out why people with higher soy intake tended to weigh less and have better metabolic health outcomes. We made some really amazing discoveries (summary here ), and I’ve been hooked ever since.
Today, researchers have identified numerous variations in thousands of genes that are involved in how your body utilizes the foods you eat. These, often very simple, differences between people’s genes can result in very different outcomes. It can range from how nutrients are absorbed (e.g., a mutation in your lactase gene that ultimately causes lactose intolerance) to a single genetic “anomaly” or variation that causes some people to lose more weight with a low-fat diet than those on the same diet but without the anomaly. When it comes to food choices, it may leave you wondering, “what can I be doing for my body?” The fields of nutrigenomics and nutrigenetics aim to address that question exactly and more.
What Exactly is Nutrigenomics and Nutrigenetics?
Nutrigenomics is the study of the comprehensive, global interplay between nutrition and your genome. It includes looking at how the foods you eat affect the expression or “reading” of your genes, the subsequent creation and building of the proteins in your cells, and what it all means for your metabolism and health. On the contrary, nutrigenetics deals with studying how different genetic variations impact how someone’s body responds to the foods they eat. What does this all mean? Remember those eggs you ate for breakfast? Nutrigenomics looks at how those eggs can affect how your DNA is read, interpreted and put into action, whereas nutrigenetics looks at how your unique DNA affects how those eggs get digested, absorbed and utilized by your body. Both are an intense area of study among nutrition scientists, molecular biologists and geneticists, and there is a great deal to be learned. While the research is ongoing, there are a few lessons we have learned so far:
Nutrigenomics: Your Diet Affects How You Handle Your DNA
“You are what you eat.” We all know that common saying and few argue against it. This knowledge has been around for over a millennium, literally, and well before our understanding of cellular and molecular biology and genetics. The famous words of Hippocrates, the father of medicine, are, “Let food be thy medicine, and let medicine be thy food.”
Fast forward to today, and our knowledge of how food affects your body has gone microscopic. Modern technology has allowed for an in-depth study of nutrigenomics to see how foods affect all aspects of your body, including your DNA. How? Oh, let me count the ways…for starters (and this is my favorite), it helps prevent the aging process…through, in part, DNA. If you remember back to high school biology, you’ll know that we have 23 sets of chromosomes. Chromosomes are just tightly wound sections of DNA, kind of like a big ball of yarn all wrapped up to keep it together, organized and neat. Each biological parent contributes 23 unique chromosomes (which is why you have the 23 sets and a total 46 individual chromosomes). Each chromosome contains a wealth of information inside to build the one and only you. So, it’s super important stuff, right? You’d probably agree that it needs to be protected. Like, very protected. Okay, but what does this have to do with my lunch? Hang tight, I’m getting there.
Example One: Healthy Foods and Telomeres
One of the ways these chromosomes are protected is by being “capped” at the end by something called a telomere. Telomeres are on each of the ends of every single chromosome in every single cell in your body. As you age, telomeres start to get damaged and wear away, leaving your DNA more susceptible to being frayed or damaged. Think of the plastic cap covering your shoelaces. If they become damaged, your laces fray, and what do you do? You go to the store, and you get new laces. Well, that doesn’t really work when it comes to your DNA, right? (At least not yet!) Therefore, it is vital that you protect your telomere caps to protect your precious DNA. How?
You guessed, it. Food! (And other things too, but I’m a nutrition scientist, so I’ll focus on the food.) For example, a study from a few years ago found that among middle-aged and older Korean adults, those who followed a ‘prudent dietary pattern’ (e.g., high in whole grains, legumes, vegetables and seaweed) had longer telomere length versus those who followed a ‘Western dietary pattern’ (e.g., high in red or processed meats, refined grains and sweetened sodas). A longer telomere length indicates preserved, “healthier” telomeres, kind of like nice, shiny, new shoelace caps. Similar studies have found similar benefits of specific nutrients, such as higher levels of blood carotenoids (the stuff that gives carrots and other orange veggies their color), on telomere length. On the flip side, other research shows excessive alcohol intake , for example, is linked to shorter telomeres.
Example Two: Plant Compounds and Nuclear Receptors
Yes, some more “sciencey” words. But, with very real meanings. Bear with me here. Each cell in your body is like its own little city, and each one monitors its own little environment inside the cell. The state of the cell’s environment gets communicated in many ways to many parts of the cell, including the DNA inside that cell. Enter nuclear receptors. As the name suggests, nuclear receptors are receptors inside the nucleus (the area of the cell where your DNA happens to be housed). Nuclear receptors can bind to different chemicals (including individual nutrients) within the cell and bind to DNA. There are many different types of nuclear receptors, each with specific monitoring jobs. For example, some monitor the level of fat within the cell (you guessed it, by binding to individual fat molecules), and then can go and physically bind to your DNA telling it to increase fat metabolism or storage within the cell (if there’s a lot of fat) or start recruiting fat from other areas if there is not enough fat.
Other types of nuclear receptors can monitor the amount of antioxidants (that “good for you” stuff found in many fruits and vegetables) in the cell and influence how your DNA gives instructions. Research shows that many of these plant compounds (e.g., resveratrol found in red wine and grapes) work through binding and influencing certain nuclear receptors to tell your DNA to “activate” anti-inflammatory and other cell protective mechanisms. Bottom line? Binding to nuclear receptors inside your cells is one way the foods you eat can communicate with your DNA and determine how its instructions are given to your body. Oh, and it’s yet another reason to eat your fruits and veggies!
Nutrigenetics: Your DNA Affects How You Handle Your Diet
Nutrigenomics and nutrigenetics are intimately tied, and both are used to determine which type of diets “best” interact with your DNA to yield a desirable outcome, whether it be to increase your vitamin absorption, help you manage your lactose intolerance, or in our case, help you lose the most amount of weight while you’re dieting. For example, one study found that 12 different genetic variations may explain some of the differences in blood beta-carotene levels (the “vitamin A” found in carrots) between men after they were provided the exact same meal full of this nutrient. Keep in mind that fruits and vegetables offer a LOT of nutrients and “good-for-you” plant compounds, in addition to just a single nutrient, so there’s still a lot to learn.
By now, everyone knows fiber is good for you, right? It’s supposed to help lower your cholesterol levels (among many other benefits). But research shows that genetic variations in genes impact how the body handles total cholesterol levels as well as “good” and “bad” cholesterol levels. For example, when it comes to fiber, one study found that genetic variations in the CYP7A1 gene (involved in how your body metabolizes cholesterol) influenced just how much eating barley fiber was able to lower total cholesterol levels in a group of men. When this happens in a variety of genes, their effect can be additive (or sometimes synergistic) creating a unique response for people who happen to have the same genetic profile.
While all your DNA, variations included, collectively provides the instructions to build “you,” some research also shows that simply one specific variation in a singular location can be enough to affect how your body responds to a specific type of diet. For example, one study found that a single variation in the TCF7L2 gene , a gene involved in many functions within the cell, can affect how much someone is able to reduce their BMI (body mass index, a measure of body weight) when following a low-fat diet. Another study looking at the exact same variation found that the presence of the variation had a significant interaction between following a Mediterranean-type diet (high in fruits, vegetables, and seafood; moderate in olive oil and nuts; low in saturated fat) and body weight and BMI. Specifically, when a group of Puerto Rican adults had a certain version of that gene and followed the Mediterranean-type diet, they tended to weigh less and have lower BMIs compared to those who did not have the variation. In essence, it may be likely that having that specific variation in that specific gene influences how much weight you lose on a diet lower in fat (especially saturated fat).
What Exactly Are Genetic Variations and How Do You Get Them?
Genetic variations are simply that. Variations in you DNA that deviate from “the norm.” Thanks to some mainstream movies, you’re probably familiar with the words, “mutant” and “mutations.” Just in case you’re not, a mutation is simply a “mistake” made when your DNA is copying itself. It needs to copy itself every time a cell replicates itself to make more cells, whether it be to build a baby from a fertilized egg or to make more cells to heal a wound. Sometimes that replication mistake does not have any effect on any outcomes, and sometimes it can drastically change the way certain parts of your body work. For example, imagine your entire genome (meaning all your DNA) as a novel, and each gene in there is a word. The words are all made up of letters. Since each time a cell is replicated, so it its DNA, it’s akin to having to replicate that novel. Now, if you accidentally make a spelling mistake while replicating your novel, but the word is still readable, no harm done. Same for most of the “mistakes” made in your DNA. (Yes, it does make quite a few mistakes overall, but thankfully, your cells have ways of dealing with it. More on that in a different blog.) However, some spelling mistakes can change the meaning of the word, maybe even the sentence, maybe even the chapter! Same for your DNA.
All these mistakes, or more accurately, mutations, over the years, decades, centuries, eons, etc. have led to our incredible diversity today. This is why some people have blue eyes, others have brown eyes, then there’s hazel eyes, you get the picture. This is a simple example of genetic variations at work. (Actually, eye color is complicated, and scientists are still trying to pinpoint exactly which genes and their variations are responsible for all the beautiful combinations out there.)
So, Does Your DNA Determine Your Destiny?
Absolutely not! It’s almost a cliché to call DNA a “blueprint,” but that’s because it’s true. DNA provides the instructions for the cell, but as you know from that last IKEA assembly, instructions can be read and interpreted many ways. Ultimately, the overall outcome of your health and wellness has to do with a combination of many factors, including both lifestyle and genetics. In fact, lifestyle plays an enormous role. Many people with predispositions to certain diseases never see them manifest, while others may have no genetic indicators yet still develop illness. So, it’s not as simple as just blaming your genes. However, when it comes to your DNA, getting a better understanding of what cards you’re dealt can help you make lifestyle decisions to try and achieve the most desirable outcomes.
Let’s look at excess body weight as an example. Regarding excess body weight, research shows lifestyle plays a large role, and research also indicates that genetic variations can provide additional influence. But neither seem to be a hard “yes” or “no” for determining the ultimate outcome. It’s more of an interplay between the two. For example, if you adjust your lifestyle and go on a weight loss diet, you will very likely lose some weight. But your genetics will impact how much weight you lose on that specific diet and where you lose it. An excellent scientific review on how gene-diet interactions can affect excess weight summarizes the research on lifestyle and genetic variations that affect body weight and related metabolism. For example, drinking too many sugary drinks, watching too much TV, and eating too many fried foods, among others, are some lifestyle factors that can cause excess body weight (see Lifestyle Chart below).
However, variations in several critical genes known to be involved in sugar or fat metabolism, among others, can affect how someone responds to different types of diets (see Genetics Chart below). Some individuals may lose more weight following a high-fat, low-carbohydrate diet whereas others may respond best to following a high-protein diet. Ultimately, following a weight loss diet that is most aligned with your genetics AND employing healthful lifestyle habits may be your best bet in preventing excess body weight. While the science is still evolving, there seems to be enough data available now to predict which diet types will yield more success for individuals depending on variations in a few key genes. Find out more about the science here and the types of genetic-based weight loss diets here.
Lifestyle Chart: Examples of several lifestyle choices and habits that can lead to excess body weight.
|Lifestyle Choices Affecting Weight Gain|
|Drinking a lot of sodas and sugary drinks|
|Eating too much fried food|
|Eating too many solid fats and foods that have solid fats|
|Watching too much TV|
|Poor sleep habits|
[Adapted from Table 1 in Int. J. Mol. Sci. 2017, 18(4), 787]
Genetics Chart: Examples of several genes with DNA variations that have been shown to influence the effect of different diet types on body weight and metabolism.
|Low-Fat & High-Carb Diet or High-Fat & Low-Carb Diet||High- or Low-Protein Diet|
|Gene With Variations||Observations||Gene With Variations||Observations|
|IRS1||Insulin response and body weight||DHCR7||Insulin response|
|FTO||Insulin response||FTO||Appetite and body composition|
[Adapted from Table 2 in Int. J. Mol. Sci. 2017, 18(4), 787.]
The Future of Nutrigenomics and Nutrigenetics
Both nutrigenomics and nutrigenetics have a bright future. Although they have been active research areas for about two decades now, their paths have just begun. As healthcare in general is becoming more and more personalized for optimal treatment options, so is nutrition. Here is a list of just a few nutrition or diet items that are already being addressed based on your genetics or will be soon:
- Vitamin absorption and utilization
- Mineral absorption and utilization
- Lactose intolerance
- Gluten intolerance
- Gluten allergy
- Fat metabolism
- Sugar metabolism
- Protein metabolism
- Diet-based weight loss
Nutrition itself is such a complex field because there are so many variables to consider both within the body, as detailed by just a few examples in the list above, but also in the foods themselves. There are millions of combinations of foods out there, and they can affect each other and how the body absorbs and processes them, when consumed together. Untangling all that data to attempt to predict how everyone’s body will be impacted under the various scenarios is a near impossible task. However, understanding the genetic component of how each person’s body can metabolize and utilize basic nutrients, including fats, carbs, and protein, while still daunting, is a more realistic endeavor. Rest assured; scientists are on it! If you’re interested in learning more about what we know so far regarding how your genetics can affect how much weight you can lose through dieting, please visit us at www.dietcypher.com.