Have you ever heard the phrase, “You are what you eat?” The explosively growing field of nutrigenomics gives this saying new meaning. “Nutri” meaning nourishment, and “genomics,” related to genes, is a whole new way of looking at food and how it impacts health and the risk of disease. Nutrigenomics, a field devoted to understanding how nutrition affects genes, looks at the basic information encoded in our DNA and how it influences our response to diet and risk for illness.
Nutrigenomics and Epigenetics
Nutrigenomics is closely related to another area of scientific inquiry — epigenetics, a field that looks at how gene expression changes with environmental exposures and how lifestyle affects gene expression. For example, you may have inherited genes that put you at higher risk for heart disease, but rather than accept your fate, you start an exercise program, don’t smoke, keep your weight under control and eat a heart-healthy diet. In response to these lifestyle changes, your “bad heart” genes aren’t “turned on” or expressed. As a result, you live to a ripe, old age and die of other causes. The field of nutrigenomics is built around the idea that the dietary choices you make affect gene expression. In the case of “bad heart” genes, eating a diet high in sugar and processed carbs and trans-fat may turn on genes that cause damage to your heart and blood vessels that, ultimately, lead to a heart attack.
The field of nutrigenomics also looks at how your body reacts to the nutrients you take in through diet in terms of your individual genetics. For example, if you received genes from your parents that put you at risk for gluten intolerance, eating gluten-containing foods may cause physiological changes in your body and symptoms that negatively impact your health. Other people, because they have different genes, are able to eat gluten without problems. This isn’t exactly earth-shattering information, but it does show how humans differ from one another. Just as individuals vary in their response to medications, people also have varying reactions to diet.
Diet and Nutrition: It’s Not One Size Fits All
Nutrigenomics squashes the idea that there’s a single “healthy” diet that works for everyone. We’re all a little different! It also may explain why research studies looking at diet sometimes deliver conflicting results. The studies don’t always control for genetic differences and variations between individuals.
What makes nutrigenomics unique is it takes individual differences into account when making diet recommendations. Most of us have genetic mutations that affect how we absorb, process and break down nutrients. If we can identify these genetic variations, we can use diet, and in some cases supplements, to alter the activity of dysfunctional genes or bypass their effects by supplying more of certain nutrients. It’s “personalized nutrition” backed by science.
Here’s another example. Some people vary in their ability to metabolize certain vitamins. A certain percentage of the population is at higher risk for vitamin C deficiency because they have a genetic variation that affects the activity of vitamin C. Vitamin C is important for a variety of bodily functions including antioxidant protection and the synthesis of collagen.
Nutrigenomics: Not Ready for Prime Time?
Of course, there are some roadblocks to the practical application of nutrigenomics. It is possible to order a genetic testing kit to see if you have gene variations that could impact your health and how you respond to diet, but you still need someone to interpret the results and make dietary recommendations based on those results. Nutritionists and physicians who are able to do this are still in short supply. Plus, it’s not clear what dietary interventions work for every type of genetic variation. Still, for people who have access to a “nutrigenomic” dietician or nutritionist, such testing may offer valuable insights into how to best structure your diet. For the most part, nutrigenomics still isn’t ready for the prime time.
One type of genetic variant codes for an enzyme involved in “methylation,” putting a chemical group called a methyl group on a molecule, is surprisingly common. Estimates are that over half the population has some variant of this gene that doesn’t function as well. As a result, they have problems methylating the B-vitamin folate and can’t easily convert it into its active form. Folate is involved in over 150 reactions in the human body, including ones associated with the synthesis of brain chemicals, expression of DNA, immune function and detoxification.
Problems with methylation are linked preliminarily with a variety of health problems including a greater risk of heart disease, brain aging, and depression, to name a few. If there’s one set of genes that has far-reaching effects on the body, it’s genes involved in methylation. Once you know you have one of these gene variants, taking certain supplements, like forms of folate that are already activated or another supplement called SAM-e, may correct the imbalance methylation problems create. That’s the power of genetic testing.
The Bottom Line?
Nutrigenomics is a growing field and one that may change the way we look at nutrition. Scientists have already mapped the entire human genome, around 21,000 genes, so knowledge in this area is increasing. Interestingly, 99% of the genes between humans are similar, but it’s the other 1% that makes us unique in the way we react to our environment.
Until nutrigenomic testing becomes more widely available, your best bet is to eat whole foods and reduce the number of processed foods in your diet. The good news about nutrigenomics is it shows that lifestyle and diet really do matter when it comes to staying healthy. Genes aren’t destiny — you have the ability to change how your genes are expressed by what you put into your body on a daily basis and other lifestyle factors. One day soon you may be able to get personalized nutritional recommendations based on your genetics, but until then enjoy foods in their most natural state.
References:
Genetics in Medicine (2007) 9, 510-517; doi:10.1097/GIM.0b013e31812e6ac3.
Genes Nutr. Oct 2007; 2(1): 11-13. Published online Sep 19, 2007. doi: 10.1007/s12263-007-0011-z
The NCMHD Center of Excellence for Nutritional Genomics” “Nutrigenomics is a multidisciplinary science”
Today’s Dietitian. Vol. 14 No. 9 P. 48. September 2012.
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