Can a DNA Test Help Determine the Best Diet for You?

Perhaps your body is particularly suited for the ketogenic diet. Maybe salmon is your “hero food”, or it might be spinach ??

This is the type of “personalized nutrition” information you can expect to receive from various direct-to-consumer DNA-testing companies (e.g., 23andMe, Helix, and Vitagene).

Obviously, the idea of getting personalized food and lifestyle recommendations based on your unique genes is incredibly sexy. It takes the guesswork out of living your best life.

The only problem? It still isn’t clear if these DNA-based diet kits can even deliver on their promises in the first place.

What does the research say about DNA-based diet kits?

It’s long been clear that we don’t all respond the same way to the same dietary interventions.

For instance, your partner might feel on top of the world despite cutting out carbs from their diet, but you might feel like you're nearly on the brink of death. But are these variations indeed due to genetic differences?

Here’s what research suggests: not really.

Entertain this thought for a moment. If genes can reliably predict the effects of a diet on an individual, then you’d expect twins to respond similarly to various kinds of foods … right?

The answer can be found in an ambitious research project known as the PREDICT study – led by a team of researchers from Kings College in London and Harvard Medical School, to figure out an individual's unique response to food. Of its 1,100 participants, the study included 700 identical twins.

And what did the researchers find?

As it turns out, genetics appeared to account for less than a third of the participants' insulin and triglyceride responses to their diet.

Instead, other factors (e.g., sleep habits, exercise, stress, and gut microbiome) appeared to play a much bigger, contributing role in an individual's response to dietary input.

It isn't just this one study that's throwing a wrench into these DNA-based diet kits' idealistic claims, either.

A 2015 review published in the OMICS: A Journal of Integrative Biology – exploring the role of 38 genes commonly involved in nutrigenomics testing – also failed to find a significant relationship between these genes and health outcomes.

Wait. So, genetic testing is completely useless?

Not at all. There are still evidence-based medical reasons to get your genes tested.

For instance, genes are known to play a role in an individual developing Type 1 diabetes, a chronic condition in which the pancreas produces little or no insulin. Lactose intolerance is also an inherited genetic trait.

There are also good genetic tests that’ll tell if you can be helped by a specific drug (e.g., one panel of tests can show whether a breast cancer patient needs chemotherapy).

An important takeaway: genetic testing isn’t useless – especially for various medical reasons.

It’s just that the entire field of nutrigenomics, which is the scientific study of nutrition and genes, currently stands on shaky scientific grounds.

Further issues with DNA-based diet kits

The primary reason for this? Research available is still currently in the infancy stage.

See: determining personalized nutritional recommendations is an incredibly complex process that requires advanced knowledge in genetics and additional information, including family history and personal risk factors.

Meaning? Direct-to-consumer DNA-based test kits are more likely than not to dispense dietary advice based on an incomplete picture of your nutritional needs.

Worse still, since these companies aren't closely regulated, you have no way of knowing if following your “genetic-informed” diet could lead to adverse health effects.

In addition to effectiveness and safety concerns, other issues pertaining to DNA-based diets include:

• Varying advice between companies: Because different companies rely on different genetic markers, they tend to give differing advice. This begs the question: which advice should you follow, then?
• Nutrigenomic testing isn’t cheap: Look at any direct-to-consumer DNA-based diet test kit out there, and you’ll find that most of them cost well over a hundred dollars. While it might not sound like much as a one-time payment, many of these test kits also require regular testing – which means the cost can snowball and fast.
• Privacy concerns: Worried about your email privacy? Imagine the things these DNA-based test kit companies could do with your sensitive genetic information. Taking inspiration from Black Mirror, imagine if your genetic information was used against you! This opens a whole new can of worms.

Focus on the basic components of a healthy lifestyle

Bottom line? Instead of obsessing over your genetic information – and how that translates into your dietary choice, focus on living a healthy lifestyle for optimal wellbeing. Pay extra attention to the following:

• Get enough sleep: In general, you should be getting anywhere between 7 to 9 hours of sleep nightly to function at your best. Regularly clocking fewer hours than that can increase your risk for various health issues, including weight gain, diabetes, high blood pressure, heart disease, stroke, and depression.
• Find ways to manage stress levels: As with insufficient sleep, unchecked stress levels can translate to problems like headaches, high blood pressure, heart problems, diabetes, skin conditions, asthma, and poor mental wellbeing. So, be sure to incorporate the necessary self-care and stress-relieving strategies into your everyday life.
• Eat a well-balanced, nutritious diet: If there’s anything we’ve learned in this article, it’d be that there’s no one true ‘best diet’. For optimal health, follow the basic tenets of healthy eating: focus on fruits and vegetables, avoid processed meats, and choose whole grains and healthy fats.
• Stay physically active: Physical activity can have immediate (e.g., it’s an instant mood-lifter) and long-term health benefits (e.g., lower your risk of several diseases like type 2 diabetes and heart problems). Be sure to include strength training elements in your fitness routine, as increased muscle mass can result in unique health benefits.

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References

Bingley, P. J., Bonifacio, E., Ziegler, A.-G., Schatz, D. A., Atkinson, M. A., & Eisenbarth, G. S. (2001). Proposed Guidelines on Screening for Risk of Type 1 Diabetes. Diabetes Care, 24(2), 398–398. https://doi.org/10.2337/diacare.24.2.398

FARHUD, D. D. (2015). Impact of Lifestyle on Health. Iranian Journal of Public Health, 44(11), 1442–1444.

Mattar, R., de Campos Mazo, D. F., & Carrilho, F. J. (2012). Lactose intolerance: Diagnosis, genetic, and clinical factors. Clinical and Experimental Gastroenterology, 5, 113–121. https://doi.org/10.2147/CEG.S32368

Our Science. (n.d.). Retrieved September 10, 2021, from https://joinzoe.com/our-science
Pavlidis, C., Lanara, Z., Balasopoulou, A., Nebel, J.-C., Katsila, T., & Patrinos, G. P. (2015).

Meta-Analysis of Genes in Commercially Available Nutrigenomic Tests Denotes Lack of Association with Dietary Intake and Nutrient-Related Pathologies. OMICS: A Journal of Integrative Biology, 19(9), 512–520. https://doi.org/10.1089/omi.2015.0109

Sparano, J. A., Gray, R. J., Ravdin, P. M., Makower, D. F., Pritchard, K. I., Albain, K. S., Hayes, D. F., Geyer, C. E., Dees, E. C., Goetz, M. P., Olson, J. A., Lively, T., Badve, S. S., Saphner, T. J., Wagner, L. I., Whelan, T. J., Ellis, M. J., Paik, S., Wood, W. C., … Sledge, G. W. (2019). Clinical and Genomic Risk to Guide the Use of Adjuvant Therapy for Breast Cancer. New England Journal of Medicine, 380(25), 2395–2405. https://doi.org/10.1056/NEJMoa1904819