DNA Diets: Everything you need to know
According to my DNA test results, I am sensitive to the effects of carbs, I metabolize caffeine quickly, and I am less likely to benefit from a lowfat diet.
Genetic testing kits with promises of personalized wellness and nutrition are surging in popularity; thousands of us bought them as holiday gifts – but are the results really meaningful?
To learn more about DNA testing and how to interpret the results, I coordinated for three of us (my husband, one of my clients and myself) to each take two different tests on the market – 23andMe and Vitagene. I am a white female, my husband is a white male, and my client is a black female. Each of us has different body types, different weight histories, and different issues around food sensitivities and our response to diet and exercise.
I reached out to Dr. Chris D’Adamo to break down the results for me, explaining what the data really means. Dr. D’Adamo is a medical research scientist with expertise in nutritional genetics and personalized nutrition. As director of the University of Maryland School of Medicine and Assistant Professor at the Center for Integrative Medicine, Dr. D’Adamo has served as Principal Investigator on a wide range of studies in the field of nutrition and integrative medicine, including how our genetic makeup influences health and aging.
“It’s important to understand the influence of our genes on weight and health,” says Dr. D’Adamo. “There’s the genetic influence, which is out of our control, but there’s a lot that is largely in our control, such as our choice of diet, movement and sleep. Staying consistent with good nutrition and regular physical activity can help to overcome genetic predisposition to obesity. Essentially, environment and lifestyle can trump genes, or at least impact the expression of our genes.”
When it comes to the DNA health reports, there is a lot of content to digest, an incredibly vast amount of data to wrap our heads around.
At first glance, all of the results look equally strong, with the same level of validity, or accuracy.
Upon closer inspection, however, we start to see that our results can vary widely in terms of what’s relevant, what is truly rooted in our genetic make-up, and what is simply population-based data that has been compiled by the DNA testing company.
Our traits, such as hair color or eye color – or how we metabolize caffeine and alcohol – are determined by dozens, sometimes hundreds of different genes. So a variant in one, two or three genes may not be significant in whether or not we display that particular trait or predisposition.
And when it comes to whole-body wellness, like our risk for heart disease, diabetes, cancer, and our struggles with weight, thing get even more complex. Lifestyle factors play a significant role; many of these conditions are influenced as much as 80 percent by lifestyle, and just 20 percent – or less – by our genetic makeup.
3 main categories for DNA test results
Results are strongly correlated to the genes tested. In this case, the genetic variants are in fact directly linked to the specific traits or predispositions that the individual displays or is a carrier for. This means that when an individual has this specific genetic variant, there is 100% likelihood that they will exhibit the related trait or predisposition – think cystic fibrosis or sickle cell anemia.
Results are loosely correlated to the genes tested. A trait or predisposition may be based on dozens or even hundreds of genes, so the one, two or three genes that may have been tested for that particular condition will reveal just a very small part of the full story for that particular trait or predisposition.
Results are not based on our genetic profile. For some traits or predispositions listed in DNA reports, these results are not actually based on our specific genetic makeup at all. Instead, our risk or tendency for these conditions is based on data compiled from other participants’ responses, then, loosely based on our personal genetic profile, the company’s statistical model determines our likelihood for these conditions.
One example is my ‘increased likelihood’ of developing type 2 diabetes according to 23andMe, with my personalized report noting that I have a 50 percent risk of developing the disease. I have no signs or symptoms to indicate an elevated risk; this report was simply generated by comparing my genetic likelihood to the baseline likelihood for someone of my age and ethnicity. Essentially, 23andMe uses an algorithm that predicts my risk for type 2 diabetes by looking at over 1,000 genetic variants and comparing these with data from over a million 23andMe research participants.
These 3 categories of test results vary greatly and should not be interpreted with the same level of significance. In spite of the wide range of significance, however, the data displayed in our results doesn’t make it immediately apparent that we need to understand and weigh the nuances of each.
How to interpret your DNA wellness profile
Start with a high-level overview, skimming the results to see what is of most interest to you. For those traits or predispositions that you’re particularly interested in, drill down into the data a bit – it’s actually easier than it may seem. Click on the link to take you deeper into the analysis of each individual result.
Depending on the DNA testing company, the data will look a little different. Most will (or should) provide an ‘overview’ section and a ‘scientific data’ section for each result. The science-focused section should reference which SNP was tested, along with your results (a SNP represents a location on a gene where a genetic variation occurs). These genetic variations, or SNPs, contribute different amounts of risk to the trait. The variant that is associated with increased risk or severity of the trait is called the risk allele. Your risk is determined by the number of risk alleles you have.
If you don’t see the science-y section for a particular trait, it’s likely that particular result was based on data collection from other participants, not on your specific genetic profile.
The bottom line: DNA tests are useful when it comes to telling us if we have the breast cancer gene, or if our kids are at risk for specific diseases like cystic fibrosis. But when it comes to prescribing a nutrition plan that tells us precisely how many calories, how much protein, carb and fat we need – or gives us a meal plan or supplement regime to follow – the science just isn’t there yet.
As Dr. D’Adamo notes, our genes are not our destiny. While our genes may influence our weight and other aspects of our health, this does not mean that our wellness is completely out of our control. Instead, view your DNA test results as a source of inspiration to take control, be mindful and purposeful in our food choices, focusing on the core pillars of wellness: nutrition, movement, sleep and stress management.
Molly Kimball, RD, CSSD is a registered dietitian + nutrition journalist in New Orleans, and founder of Ochsner Eat Fit nonprofit restaurant initiative. Tune in to her podcast, FUELED | Wellness + Nutrition and follow her on Facebook, Instagram and Twitter at @MollyKimballRD. See more of Molly’s articles + TV segments at www.mollykimball.com.