Do DNA-based diets work?

Stacey C. Slagle

Will you succeed or fail on a ketogenic diet? Will exercise be more important than food choices if you want to lose weight? The answer to these questions may lie within your genes. Genetic analysis is contributing to a growing area of nutritional medicine that offers dietary prescriptions — including personalized diet plans based on nutrigenomics — to help people make more informed decisions about their lifestyle habits and health.

The Cleveland Clinic has been providing personalized nutrigenomic testing for several years. As a dietitian there, I can see firsthand the benefits it provides to patients. It’s especially useful for patients who have found themselves “stuck” in their weight-loss efforts. Having a genetic insight into the types of diet that work best for them often increases both compliance and sustainability.

I pinpoint about five of the most important genes to focus on with my patients based on their goals. This may involve changing the type of workout they are doing, altering the percentages of fat and protein in their diet, suggesting specific supplements, like methylated folate or vitamin B12 and increasing certain nutrients from food, like vitamin A or iron. Often, my recommendations are in line with supplemental laboratory data for the patient as well.

What is nutrigenomics?

A relatively new scientific discipline, nutrigenomics focuses on the relationship between genes, nutrition and health. It seeks to explain how our bodies respond to what we eat and drink — and how we can use that knowledge to promote activity in our “good” genes and suppress it in “bad” genes. Diet plans based on nutrigenomics rely on an analysis of your genetic makeup to inform dietary recommendations that meet your personal nutritional and health needs and help prevent nutrition-related chronic diseases.

“The ultimate goal of nutrigenomic testing is to identify sub-groups of populations who may respond to diets differently or show distinct intolerances to foods or susceptibility to diseases,” Dr. Lu Qi, an adjunct professor of nutrition in the Harvard T.H. Chan School of Public Health’s nutrition department told TODAY in an email. “Such a goal is promising and increasingly supported by scientific evidence, including those from our studies.” Qi explained that this type of personalized approach is expected to improve the efficacy of dietary recommendations. However, he said, “the research of nutrigenomics is still in its infancy. At this stage, it’s more important to accumulate evidence than to generate recommendations.”

Related: DNA tests promise to help you tailor a diet, supplements and exercise for optimum weight, heart health and lifestyle. But can they really deliver?

Personalized diet plans are not a new concept. They started gaining traction about 20 years ago with an approach that helped people lose weight by eating and exercising according to their blood type. The blood type diet garnered a lot of interest but lacked strong scientific backing. Nutrigenomics emerged in the early 2000s after the Human Genome Project (HPG) was completed. Though scientists were aware for decades that genes played a role in health, the HPG helped them gain new insights into the connection between bioactive compounds in food and their impact on genes — and on people’s health. They discovered that lifestyle choices could direct genes to either work to the body’s advantage, or to its detriment.

The science behind personalized testing

Multiple studies have shown that genetics come into play with our eating habits. Research also suggests that knowledge of our genetics can influence how well we comply with dietary prescriptions. For example, a 2014 randomized controlled trial showed that participants who possessed the risk variant of the ACE gene (a gene that directs the body on blood pressure levels) were able to significantly reduce their sodium intake compared to the control group; they also maintained their lower sodium intake one year later.

Another study published last month in the British Medical Journal demonstrated that individuals given nutrigenomics-guided dietary advice for total fat and saturated fat intake significantly reduced their long-term intake compared to gold-standard population-based interventions.

Other studies, however, have suggested that gene-based dietary interventions may not be as promising as once thought. The results of a randomized clinical trial that followed more than 600 overweight adults for a period of 12 months found that a genotype eating approach was not “associated with the dietary effects of weight loss.”

While the concept may have potential, more research is needed to affirm the efficacy of gene-based diets. Qi underscored that a balanced diet, exercise and adequate sleep benefit everyone, regardless of their genomic makeup, but he suggested that certain sub-groups are likely to be more sensitive to different diets — a low-fat vs. a high-fat diet, for example, or certain specific exercise regimens. “However, current evidence is still far from sufficient (for doctors or dietitians) to provide practical guidelines,” he said, “and the personalized recommendations will be built on accumulating data in the future.”

The potential benefits of a DNA-based diet

The ability to customize diet and exercise plans based on an individual’s genetics may be the next frontier in nutrition counseling. A personalized dietary plan may help increase compliance, as well as help you target dietary and physical activity goals that are more in line with what works for your body.

“While food and nutrition guidelines set by government agencies are important to follow, evidence has demonstrated that those one-size-fits-all nutrition recommendations can be inefficient and often ineffective,” said Dr. Ahmed El-Sohemy, a professor and Canada research chair in nutrigenomics at the University of Toronto and founder and chief science officer of Nutrigenomix, Inc., a company that does genetic testing for personalized nutrition.

Dr. Christopher Lynch, the director of the Office of Nutrition Research at the National Institute of Diabetes and Digestive and Kidney Diseases, told TODAY in an email that the NIDDK’s new 2020-2030 Strategic Plan for NIH Nutrition Research is centered on the unifying theme of precision nutrition, which focuses on personalized eating plans based on DNA and includes nutrigenomics. “There are many factors that affect individual responses to diet, including diet-gene interactions, that need to be taken into account when developing comprehensive and dynamic nutritional recommendations relevant to both individual and population health,” he said. Lynch also stressed that “more research is needed to fully understand the impact of these factors and their interrelationships.”

Is nutrigenomic testing right for you?

“Genetic variation is an important component of why people differ from one another in their metabolism,” Dr. Steven Zeisel, the director of the Nutrition Research Institute at the University of North Carolina and founder of SNP Therapeutics, told TODAY in an email. “Genetic testing and nutrigenetics have a lot to offer, but may not be ready yet to tell someone which diet will make them lose weight.”

Aside from the fact that the research is still in its early phases, nutrigenomic testing isn’t cheap, so cost can be a concern. The price for a test and analysis starts at about $300. Privacy is another common concern. “Some individuals may worry that their genetic information could be used to discriminate against them in their job or with their health insurance coverage,” said El-Sohemy. But he also noted that the “Genetic Information Non‐discrimination Act (GINA) was signed into law in May of 2008 and offers federal protection against such discrimination.”

There are dozens of tests on the market that provide analysis on the genes involved in nutrient metabolism and response, including Ancestry and 23andMe, but once you receive the results, you still need to seek out a specialist to analyze the raw data and make recommendations. If you’re interested in learning more about DNA-based diets, speak to your doctor about getting a referral to a reputable medical group that offers nutrigenomic testing.

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