In the world of personalized nutrition, it’s well accepted that there is no "one size fits all" diet. But recently, the concept of individualized diets have been taken to the next level thanks to a slew of genetic testing products promising DNA-based nutrition plans. So that begs the question: how much does DNA actually influence your diet? While the potential seems very high, unfortunately, the science isn’t quite there yet. Here's why you should be wary of any DNA test that promises a perfect diet plan based on your genetics.
A quick lesson on using DNA to predict traitsBefore we jump into the science of genetics and nutrition, let's take a step back into high school biology. Our DNA is essentially the instruction manual for everything inside our bodies. From proteins, to hormones, to enzymes, DNA tells our bodies and cells how to build critical biological components—and almost every cell in our body contains a complete set of DNA.
You can think of your DNA as a bookcase. The bookcase is organized into separate shelves that we call chromosomes. On those shelves are books, which represent genes, that act as instruction manuals for our body. If we open up a book, we see words and letters (nucleotides) which represent our genetic code.
Now, humans share a common 99.9% of DNA. But it’s the remaining 0.1% that makes us all unique. Part of these differences are small, single nucleotide variations called single nucleotide polymorphisms or SNPs (pronounced "snips"). Scientists have researched these SNPs and have found that they can predict certain outcomes or traits in people. This ability to predict traits is essentially the premise for the DNA tests that you can purchase today. If you want to take a deeper dive into the science behind DNA, check this blog out.
DNA can unveil some interesting points about intolerancesAs you may have imagined, the answer to whether DNA can predict your ideal diet isn't an easy 'yes' or 'no'—in fact, it's both. In some cases, scientists have been successful in using DNA to predict foods someone should stay away from—we're aware of several SNPs that can predict someone's risk or potential for certain nutritional allergies or intolerances.
At InsideTracker, we currently test and analyze DNA for three food sensitivities: peanut allergies, gluten intolerances and lactose intolerances. It’s important to remember, though, that your DNA merely illuminates an increased risk for one of these intolerances. A commercially-available DNA test won't tell you for certain whether you currently have a specific allergy or intolerance. For example, genetics only account for up to 6% of the risk for a peanut allergy—other environmental factors also play a critical role. DNA is a great starting point for our health and wellness, but it’s not a sealed fate.
Now, when it comes to food preferences, there are a few more interesting things that might be a result of your DNA. Do you know someone (or are you that someone) who can't stand the taste of cilantro? Well, they’re not crazy. People who have an alternate variant of the gene OR26A often sense a “soapy” taste from cilantro. In a similar fashion, those who carry an alternate variant of the gene TAS2R38 are known as “super tasters.” This genetic variant codes for an extra taste receptor on the tongue that responds to bitter foods, making vegetables like Brussels sprouts or broccoli taste extra bitter. So while our DNA can't decode our food preferences entirely, it does hold the key to some interesting traits and quirks!
DNA alone can't fully construct your ideal dietA dietary approach that has recently entered the market is genetics-driven nutrition plans. And while we do know that DNA has a very strong influence on how you absorb and metabolize food, we have to remember that DNA doesn’t tell the whole story. Your DNA provides a great starting point to unveil your body's potential, but there’s a lot more at play here, including epigenetics—how your body expresses genes—and your lifestyle.
There have been several studies that analyze the effect of genetic-based nutrition plans. In one randomized controlled trial, one group of participants were given conventional dietary advice while another was given personalized nutrition advice based on their genetics. Unfortunately, dietary advice based off of genetics did not enhance the effectiveness of the nutrition plan. In a similar study, no association was found between genotype (a variant of a particular gene) and weight loss when testing either a low fat or low carbohydrate diet.
Identical twins are considered a gold mine for studying the contribution of genetics to nutritional outcomes because identical twins have virtually identical DNA. This allows researchers to easily apply the 'nature vs. nurture' hypothesis to the body's response to food—that is, to explore whether a food acts in an individual because of their genes or because of their lifestyle and environment. In one particular study published in 2019, researchers analyzed the metabolic responses of several hundred pairs of identical twins. When consuming the same meals, twins had vastly different metabolic responses, including in elevations of blood glucose, insulin sensitivity, and even triglyceride levels. This just goes to show—even in those with identical DNA, genetics doesn’t tell the whole story about foods' impact on our bodies.
So how can you biohack your ideal diet? Combine blood with DNA.At InsideTracker we like to say, "DNA isn’t destiny!" Your DNA can provide unbelievable insights into what’s going on inside your body and how you might respond to certain foods—but it only reveals your body’s potential. DNA insights are therefore limited when considered alone. The real power comes from the combination of your genetics with snapshots of what’s actually going on inside you in real time, which we can get from blood.
Let’s say your InsideTracker DNA Report says you have an increased risk of high LDL (the "bad" cholesterol). This doesn’t necessarily translate to "you have high levels of LDL," because things like your diet and lifestyle also come into play. To answer this for certain, we have to look at your blood! You may in fact have high LDL, and because of your increased genetic risk, you have to make changes to lower them. But it's also possible that you have optimized levels of LDL and should maintain your current lifestyle to overcome your genetic potential. DNA matters most in context.
When we combine DNA analysis with your blood biomarker levels, we get to see a bigger picture: whether you’re living up to your genetic potential. With these two tools, InsideTracker can provide you with deeper, more personalized insights into what’s really going on inside you.
A summary of genetics' impact on your ideal diet
- We can use DNA to identify increased risk for things like allergies, intolerances, or food preferences, but increased risk does not equate certainty
- Your DNA can highlight predispositions for certain health risk factors tied to diet (like bad cholesterol)
- If you want to use DNA to construct your ideal diet, this is best done in conjunction with data from your blood
- Combining DNA and blood results is the best way to know how your DNA is affecting your daily life and diet
 Celis-Morales C, et al. Effect of personalized nutrition on health-related behaviour change: evidence from the Food4Me European randomized controlled trial. International Journal of Epidemiology. 2017. Gardner CD, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA. 2018.
 Berry S, et al. Predicting Personal Metabolic Responses to Food Using Multi-omics Machine Learning in over 1000 Twins and Singletons from the UK and US: The PREDICT I Study. Current Developments in Nutrition, 2019.