Kathy Kolasa: Benefits of genetic testing on nutrition limited, so far | Columnists

One reader asked why I start each column with a reminder to eat healthy, be physically active and follow the three Ws. “You would think we would all know it by now,” he said. I said, looking around, we all need gentle reminders.

Q What is precision nutrition, and are genetic testing kits useful for making the best eating choices for your health? MF, Greenville

A People are having fun with ancestry testing kits and might be tempted to try a genetic testing kit to prescribe a diet just for you. In my view, the science is building but if I were you, I would save my money and spend it on a consult with a registered dietitian nutritionist who can work with you to personalize your diet. Amy Lewis, a senior ECU dietetic student, has some information to help you make an informed decision.

Precision nutrition is an exciting area of nutrition research that aims to make nutrition care more individualized. It does this by looking at how several factors that are unique for every person affect nutrition. These factors include genetics, gut microbiota, metabolism and more. The topics which are usually front and center in discussions of precision nutrition are nutrigenomics and nutrigenetics.

Nutrigenomics is the study of how what we eat can influence how genes are expressed, while nutrigenetics is the study of how genetic variants can affect the body’s metabolism and how it responds to what we eat. Nutrigenomics and nutrigenetics are new fields of research, so what we know about them right now is limited.

Most nutrition-related disease states, like obesity, are related to several different genetic variants, rather than just one. Because of this, studying the genetic variants that affect your health as they relate to nutrition is difficult. The only health outcomes which can be reliably predicted right now based on genetic information are monogenic diseases, which are caused by the changing of only one gene product. Lactose intolerance and caffeine sensitivity are in this category. However, many nutrition-related diseases, like obesity, type 2 diabetes, and cardiovascular disease, are more complicated. So, right now we can’t predict them based on genetic information alone.

The relationship between the genome and nutrition is complicated, so we don’t have much research that supports making changes to one’s diet based only on information we are currently able to collect about one’s genetics. Despite the limitations of this research, companies have begun to market both direct-to-consumer and professionally administered genetic testing kits to tell consumers how their genetic makeup may affect what they should be eating to promote health. These tests are becoming more and more popular, partially since the average person is more likely to be able to afford these kits now than in previous years, as there has been a huge decrease in the cost of genotyping and sequencing. These tests now typically cost around $200.

The companies may claim to develop a diet that is ideal for you to consume to promote health based on your genetic background, or to determine your risk for developing diseases that are related to nutrition. While this sounds great, the limitations of the research and the fact that these companies often don’t reveal much information about which genetic variants they’re basing their risk assessments and recommendations on raise questions about the diet’s validity and, by extension, whether they are worth your time and money.

So, is the purchasing of a nutrigenetic testing kit worth it? Well, almost all recommendations you can identify based on these tests align with recommendations that have already been established for healthy eating, with very few exceptions. Also, studies have shown that learning more about your genetic risk for nutrition-related diseases and traits doesn’t necessarily motivate you to change your dietary behaviors. You may do just as well by simply sticking to the 2020 Dietary Guidelines for Americans.

If you do purchase one of these tests, it may be best to talk to your doctor or a registered dietitian nutritionist (RDN) about what kits they would recommend or which are available to be administered through them, rather than purchasing a kit that is directly available to consumers. If you think it will act as a motivator to make good decisions regarding nutrition based on well-established guidelines to promote your health rather than a basis for you to make all your eating choices and you can afford the fee, it is unlikely to do any harm.

Professor emeritus Kathy Kolasa, a registered dietitian nutritionist and Ph.D., is an affiliate professor in the Brody School of Medicine at ECU. Contact her at kolasaka@ecu.edu.

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