Q. I keep seeing these DNA testing companies on social media. I haven’t done the test, but I read a sample report, and it seemed like the recommendations (i.e., eat a high fiber diet) were just common sense and would apply to everyone. Also, recommending supplements based on my results sounds suspicious. I know you talk a lot about personalized nutrition and individual biochemistry, so do you support these test results and theories?

A: Since the sequencing of the human genome, there’s been a lot of piqued interest in nutrigenomics. Nutritional genomics, also known as nutrigenomics, is a science studying the relationship between the human genome, nutrition, and health. Research is directed toward understanding how the whole body responds to food via biology and single gene/single food compound relationships.

It’s been clear that we don’t all respond the same way to the same dietary interventions. Some people do well on a higher fat diet, while others develop high triglycerides on the same diet. Some people lose more weight when they reduce carbs. Others lose more weight when they increase complex carbs and reduce fat. Hence, the need for more personalized nutrition.

Okay, so If these differences are genetic, maybe we could skip some of the trial-and-error and zero in on each unique individual’s best approach based on their DNA. Makes sense, right? And now that inexpensive mail-order genetic testing is available, companies have started selling personalized nutrition programs that are supposedly based on your DNA.

If these differences are genetically driven, then we would expect the identical twins to respond similarly. But they didn’t. In some clinical trials, genetics appeared to account for less than a third of the subjects’ insulin and triglyceride responses. The specific ratio of fats and carbohydrates in the diet were also not strongly predictive. Other epigenetic factors, such as sleep habits, exercise, stress, and gut microbes, appeared to play a much more significant role in our individual responses to diet. Epigenetics means “above” or “on top of” genetics. It refers to external modifications to DNA that turn genes “on” or “off.” These modifications do not change the DNA sequence, but instead, they affect how cells “read” genes.

What does this mean? Well, we can’t change our genes. But we can change how much we sleep, how we manage stress, and how much we exercise. We can even influence our gut microbes.The core components of a healthy diet and lifestyle are pretty universal. Everyone will benefit from eating more whole foods, avoiding excessive sugar, alcohol, and processed food, getting enough sleep, and moving their bodies. On the other hand, the more I can help you learn how to tailor your diet and habits to fit your individual needs, preferences, and lifestyle, the better and more sustainable your results will be.

You can have your healthcare practitioner monitor biomarkers like your cholesterol and blood sugar levels. But between visits, you have access to a lot of other information. Is your weight trending up, down, or staying steady? How are your hunger levels, energy, and stamina? If you’re not happy with the status quo, make some changes, and observe what happens. No DNA testing required.

I’m not arguing against testing (I’m fascinated with all testing data and all the emerging options); I’m just saying that, at present, it doesn’t look like DNA testing is the most useful approach. Our best toolbox tool is to observe how your body responds to a given approach and adjust based on your results.

Takeaway: As always, different people respond very differently to the same dietary inputs. There is no one dietary approach that’s going to work best for everyone. Eat your vegetables.

Christina Wilson


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