Historically, dieticians have been restricted to offering ‘one-size fits all’ approaches to diet planning. But with recent advancements in genome sequencing technology, the field of nutrigenomics could revolutionize how diet plans are created. 

Nutrigenomics studies the interactions between genes, nutrients, and other bioactive food compounds at the molecular level, and how these interactions can affect individual health.

Inherited genetic variation between individuals can alter the absorption and metabolism of bioactive food compounds, as well as the different biochemical reactions that those compounds are involved with. These genetic differences contribute to a variation of individual responses to certain foods.

“We’ve always seen that some individuals respond differently from others to the same foods, beverages, nutrients and bioactives consumed,” wrote Ahmed El-Sohemy, a professor in the Department of Nutritional Sciences, in an email. “Nutrigenomics helps us understand this variability in response so that we can predict who’s likely to benefit from a particular dietary intervention, and who might need a different approach.”

El-Sohemy is also the founder of a U of T startup called Nutrigenomix Inc., which aims to use individual genetic information through a saliva sample to offer personalized dietary recommendations to achieve positive health outcomes. 

Genetic testing through Nutrigenomix is administered exclusively through health care professionals. “Healthcare professionals can help individuals identify evidence-based tests and, equally important, they can guide consumers in interpreting their results, provide sound recommendations, and offer tips to incorporate these recommendations into their lifestyle,” wrote El-Sohemy.

One of the genes that Nutrigenomix tests for is called CYP1A2, which codes for a protein involved in breaking down caffeine. Genetic variations between individuals can differ the rates at which caffeine is digested after consumption.

Individuals with a version of the gene that is less efficient at breaking down caffeine “are at increased risk for cardiovascular disease, all the way from elevated blood pressure to heart attacks, when consuming more than 200 mg of caffeine per day,” wrote El-Sohemy.

According to the Centre for Addiction and Mental Health, the average Canadian consumes 210–238 milligrams of caffeine per day, or about two small cups of coffee. As such, results of this test could caution regular coffee drinkers to think twice before pouring their next cup.

Other examples of genes that are sequenced as a part of the Nutrigenomix panel include those related to vitamin C uptake relative to consumption, gluten intolerance, and high blood pressure associated with high-sodium diets.

Since its launch in 2012, Nutrigenomix has grown from a panel of seven genes to 45, with the launch of a larger panel in the near future. “We now have genetic tests focusing on general health and fitness, athletic performance, and fertility,” wrote El-Sohemy.

As with any new technology, nutrigenomic testing is not without limitations.

Nutrigenomics is far more complex than sequencing a person’s genome, and must incorporate many different ‘omics’ that exist outside of the linear sequence of a gene.

This includes epigenomics, transcriptomics, proteomics, and metabolomics, all of which researchers have limited understandings of in terms of individual responses to certain bioactive food compounds and their resulting health outcomes.

There is also growing interest in the role that the microbiome, or the genetic component of a collection of primarily bacteria in the human gut, has in individual responses to certain foods. 

As researchers continue to gather information on the many dynamic interactions between genes and nutrients, and genetic sequencing continues to become faster and cheaper, we could see a shift in how diet plans are customized for individuals.

“Nutrigenomics is definitely not some fad that will pass,” wrote El-Sohemy. “It’s the new way of looking at nutrition by considering the genetic makeup of the individual, which the scientific evidence shows is important to understand before making a recommendation.”