Should I Eat for My DNA?

The nutrition myth buster Jonny Bowden weighs in on whether there is any truth to the concept of eating for your DNA.
Publish date:


Eating for your DNA is an idea with tremendous potential. But don’t rush off and do a happy dance in the end zone – at least not just yet.

Using DNA testing for the purpose of finding the right diet and workout program is still a very new concept and has a number of limitations you should be aware of.

Let’s start with expectations. Genes are, contrary to popular opinion, generally very malleable, not at all the fixed quantities most people think they are. In most cases, knowing your genes is like knowing the cards you’ve been dealt in a poker hand. The cards are important, but there wouldn’t be millionaire poker players and ESPN tournaments if the skill you played with was less important than the cards themselves.

Whether or not a gene is expressed — i.e., whether or not it actually does something you can observe and measure — is significantly influenced by environment, diet, toxic exposure and a baker’s dozen of other factors. (Bears are genetically programmed to hibernate, but if the climate is warm, it’s a no-go.) In fact, entire disciplines of science have been developed that study exactly how nutrition and environment impact our genes (nutrigenomics for the former, epigenetics for the latter).

That said, certain patterns of genes can suggest that a person might do better on one kind of diet than another. A recent study provides an example: Researchers put people on a variety of weight- loss regimens. As is often the case, the results were all over the map, with some people losing weight and some people, well, not. But when the researchers plugged in a genetic test, some distinct patterns began to emerge. Some genetic types did better on some diets, while other genetic types did better on other diets. Once genetics were factored in, the results began to make more sense.

Here’s an example: The APOE2 gene has a lot to do with how your body handles dietary fat. People with a certain variant of this gene are able to extract every bit of energy and nutrition from fat, their bodies have all the pathways in place to optimally break down fat and their enzymes are functioning well, so when these folks eat fat, all is right with the world. Folks with a different variant of APOE2 feel terrible on high-fat diets. Knowing this, along with other genetic markers, might help you decide if you are a good candidate for a keto (high-fat) diet, and these variants may help explain why some people thrive on such diets while others don’t.

Similarly, variants in the HLA-DQA1 and HLA-DQB1 genes increase the risk of developing celiac disease. But increasing the risk of something happening is not the same as making it happen. Even the dreaded BRCA mutation raises a woman’s risk for breast cancer from about 12% to about 70%, but it doesn’t raise it to 100%! The danger with genetic testing is thinking that your DNA determines everything. It doesn’t. What you do still matters a lot.

To complicate things further, knowing you have a particular gene may not even make much of a difference in your behavior or your diet, especially if you’re already doing all the right stuff. Suppose you are a person who exercises daily and eats an extraordinarily healthy diet with tons of cruciferous vegetables and filled with every nutrient known to have anticancer activity. Then one day you find out you have a “bad” gene (like the mutation of the BRCA gene that Angelina Jolie had). I mean, really, besides more vigilant screening, what are you going to do differently? (Of course, if you’re eating seven meals a day at fast-food restaurants and then you find out you had the BRCA mutation, it might be time to change your diet!) But the truth is, most people have something they can improve upon in their diet or lifestyle.

Another thing to remember about genetic testing is that the tests you want for diet and exercise are not the widely advertised commercial tests that promise to connect you with your long-lost relatives. Those tests are useless for determining what you should eat or how you should exercise, despite marketing claims to the contrary. To get info that you can actually use, you’ll have to go to a much more extensive (and expensive) test like those provided by Pathway Genomics in the U.S. or Youtrients in Canada.

Pathway Genomics offers tests that look for patterns of genes that make it more (or less) likely that you will do well on a particular eating plan. (Remember the first caveat: We’re talking predictions, possibilities, likelihoods and percentages, not certainties!) Pathway developed algorithms, for example, based on genetic traits in over 1,100 marathon runners to develop their “marathon runner” profile, which they claim helps athletes train more efficiently.

They also have a FIT IQ test, which looks at genetic patterns that may predispose you to being better (or worse) at processing sugar and/or fat. A typical report might tell you that you are a fast metabolizer of caffeine (the CYP1A2 gene determines this), whether or not you have lactose intolerance and whether you should focus on endurance training more than weight training.


You might find that you have a genetic disposition to “enhanced” bitter taste perception, or that your genes make it very likely that you’ll find snacking irresistible.

All this sounds great, but be cautioned: Some of the suggested actions are pretty vague and not much different than you’d get from a pamphlet in a doctor’s office. One example: There’s a genetic variant that is associated with “increased food desire.” If you have this variant, here’s the advice: “Try to tame your eating behaviors.”

All that said, the Pathway Genomics test is pretty good and darn interesting. You might find that you have a genetic disposition to “enhanced” bitter taste perception, or that your genes make it very likely that you’ll find snacking irresistible. (But really, don’t you kind of know that already?) They do, however, offer the best test I’ve seen so far if you’re looking for some basic guidelines (i.e., eat a low-carb diet, or emphasize endurance training).

Youtrients takes a slightly different approach to genetic testing. Their goal is to design a completely individualized supplement program based entirely on your genetics. They do this by looking at genetic vulnerabilities and strengths in different metabolic pathways (i.e., methylation), and then design supplement programs to proactively counter any weaknesses found in the genetic report. One of the markers they test for is something called PK21, which tells you how susceptible your arteries are to inflammatory substances. One variation of PK21 means your arteries are like Teflon, while another variation — the one I happen to have – tells you they’re more like a Teflon knockoff with a lot of scrapes in the surface. If you have a “not so good” variant of that gene as I do, you’d be well-advised to banish inflammatory foods (like sugar and gluten) from your diet. And the Youtrients algorithm would increase anti-inflammatories like fish oil and quercetin in your personalized formula.

Further to these forms of genetic testing, the Weizmann Institute of Science in Israel, which has one of the largest microbiome databases in the world, is beginning to offer a personalized genetic test that investigates how foods affect your individual microbiome. A company called DayTwo has developed an extraordinary app using the Weizmann Institute’s research – it is individually programmed with your results and lets you see exactly what foods will have a net positive effect for your microbiome (for instance, foods that increase energy and support digestion) and what foods have a net negative effect. These tests — and the app — are available now. (A good place to learn about this kind of genetic testing and personalized diet is the TED lecture entitled, “What is the best diet for humans?” by Professor Segal of the Weizmann Institute.)

The takeaway is this: DNA testing is the future of personalized medicine. Everyone I know in the field is certain that the day will come when doctors won’t have to guess which dose of statin to put a patient on because they’ll know exactly what dose this particular patient is likely to respond to and will prescribe accordingly. DNA will ultimately tell us more about what diets work best for us, what exercise routines will be most productive, what we gain muscle on, what makes us feel sexy or depressed, and what makes our little dopamine reward circuits fire like the pinball machine in Tommy.

We’re just not there yet. Not even close.

In the meantime, companies like Youtrients, Pathway Genomics and the Weizmann Institute are offering really interesting reports that go into far more detail than those heritage-type kits they sell on Amazon. Just remember to take what you learn about your genes with a big grain of sea salt.

Predictions based on DNA are about as reliable as predictions in elections. Many times they’re right, but they’re wrong enough times that you shouldn’t take them as gospel.