If you’ve spent any amount of time online over the past few years looking for nutritional information or guidance, chances are you’ve been served at least one targeted ad for at-home genetic testing that claims to provide you with guidance on becoming your healthiest self, based on your ancestry.

It sounds great! A personalized, scientifically-derived nutrition plan? Aren’t we always talking about how there’s no one-size-fits-all solution to diet, after all? Seems like the perfect pathway to personalized nutrition… heck, it almost sounds too good to be true.

So Is it? Let’s unpack what goes into these DNA diet tests.

How do DNA-based nutrition tests work?

The process of taking one of these nutrition DNA tests isn’t terribly complex:

1. You swab the inside of your cheek or spit into a tube and send it back to the testing company.

2. They analyze your DNA, looking for small variations in specific genes to determine your unique genotype.

3. This information is then used as the basis for a report about your gene variations, most notably whether or not you possess genes for common dietary sensitivities (like lactose intolerance), things like Celiac disease, and whether you have difficulty processing things like fats, carbs, or even coffee.

What's the approach?

More specifically, these DNA nutrition tests dig into data originating from science’s successful sequencing of the human genome – this breakthrough has led to a rapidly increasing interest in the field of nutrigenomics.

We’ve long known that we don’t all respond to the same dietary inputs in the same way. For instance, while some people thrive on a higher fat diet, others might develop high triglycerides or cholesterol by eating the same way.

If these outcomes are entirely genetically driven, theoretically it would be possible to bypass the usual trial-and-error approach we take in nutrition science, and jump right to the ideal diet for each individual based solely on their DNA.

These mail-in tests have become inexpensive, so it might be tempting to try one of them out. After all, a personalized nutrition program based on your DNA sounds pretty great, right?

But what does the science say about the efficacy of this approach?

What does science say?

Despite the flashy marketing and seemingly surefire science behind nutrigenomics tests, the actual scientific consensus isn’t as clearcut.

Let’s take a look at the PREDICT study, an expansive research project undertaken by teams from Kings College in London and Harvard Medical School. In this ambitious study, researchers evaluated things like the rise and fall in blood sugar and blood fat experienced by 700 identical twins and 400 non-twins after consuming various foods. The goal was to explore which diets might be most effective in preventing common ailments like diabetes or heart disease for given individuals.

Findings presented at the 2019 meeting of the American Society of Nutrition confirmed what was largely held to be true: that there is no one magic diet that works best for everyone. 

But interestingly, this held true even for identical twins. You might expect identical twins – who possess identical DNA – to respond similarly to the same foods. But that wasn’t the case in the PREDICT study.

In fact, genetics appeared to account for less than a third of subjects’ insulin and triglyceride responses. Specific ratios of fats and carbs in test diets weren’t terribly predictive of outcome. Instead, lifestyle factors like sleep, exercise, stress, and even gut microbes all appeared to play larger roles in individual response to food inputs than diet itself.

So what does that mean? Well, for starters, it sort of puts a damper on many of the promises made by companies selling DNA-based diet tests. But it’s also good news for… well, everyone else. We can’t change our genes, but that’s fine from a diet standpoint as they’re only one factor that goes into how our bodies process the foods we eat. And we can change – within reason / our schedules permitting! – how we sleep, exercise, manage stress, and even our gut biomes.

Why your response to food is much more complex

The first and biggest issue with these DNA diets/nutrigenomic tests is that they assume that a characteristic exhibited by an individual is wholly explained by a single gene or a few genetic variations. Your response to food is incredibly complex!

Most of the traits we exhibit are influenced by not just one gene, but groups of hundreds of them, which can manifest in nearly infinite permutations. Tests looking for just one or two variations on a single gene simply aren’t that useful.

Our bodies are incredibly sophisticated systems, and there’s elaborate interplay between our many, many genes, and the things we eat, drink, and do throughout the day, on top of a whole range of environmental factors from the world around us.

(Then there’s another small issue: predictions of actual, real world traits by at-home genetic tests aren’t always accurate. Even for something as seemingly simple and obvious as eye color.)

So, are there any benefits to getting a DNA nutrition test?

Short answer, probably not. Longer answer, there isn’t likely to be anything harmful in taking a test, but you likely won’t get any truly meaningful information from a DNA food test.

So many genetic tests exist, and they don’t all agree on what genetic variations mean for responses to given foods – you might get entirely different dietary suggestions from competing companies, based on similar tests from the same DNA. The simple truth is we still have a long way to go to fully understand how our genes impact our bodies’ abilities to process foods, so any advice derived from DNA tests is likely to be a bit misleading at best.

What have we learned? Eat your fruits and vegetables - no matter your DNA!

If you’re still on your own personal journey to answer the age old question “which diet is best for me?” you’re not alone.

It’s true that the more you can dial in your diet and habits to best serve your individual needs and lifestyle, the better off you’ll be and the more sustainable the results. But right now, DNA testing isn’t going to prove particularly useful in helping you reach this point.

And that’s totally fine. Through trial and error, you can easily figure out what to include in your regular routine to maximize feeling good. And while the specifics of what constitutes a healthy lifestyle and diet may vary for every person, the broad strokes don’t. At the most basic level, the surest way to take care of yourself is to eat a whole bunch of fresh fruits and veggies.

That’s because a diet full of produce is…

• Full of vitamins, minerals, and antioxidants – all of which can help support your immune system and reduce your risk of some chronic illnesses;

• High in fiber, which is essential for healthy digestion and also helps you stay full for longer;

• And even one that can actually improve your mental health – studies suggest that individuals who eat a diet richer in fruit and veg tend to report higher levels of general happiness.

So until DNA nutrigenomic test technology can catch up to what these tests currently claim to do, what’s a person to do? Just try to eat more fruits and vegetables, and if you notice certain foods leave you feeling good, while others leave you feeling not so good, eat more of the former and less of the latter. 

Of course, this being a kencko blog, you know we’ve gotta mention a few ways to up your produce intake without having to really change much else in your life, that just happen to be kencko products. Try some delicious  kencko smoothies for a daily fruit and vegetable boost! Our bowls are also the perfect, healthy, balanced lunch or dinner option. And a sneaky way to integrate even more fruit and veg into your diet is our gumdrops!