Genetic info should be bedrock of personalized nutrition, expert says
Speaking at the Day of Science portion of the Council for Responsible Nutrition’s annual meeting, Chris D’Adamo, PhD, said that understanding these differences from individual to individual will be the primary factor that drives future product development in this area. Up to now measurements of individual nutrient status and a customer’s overall health and nutrition habits have taken center stage when it comes to thinking about what kind of information to gather when trying to customize a product for an individual. This tack has been taken primarily because it’s cheap, easy and noninvasive. But D’Adamo, who is an assistant professor in the Department of Family and Community Medicine at the University of Maryland School of Medicine, said without some key genetic information, the answers to these questions might mean little. The interplay of nutrient intake on gene expression is complex, and the full picture has only recently started to come into sharper focus, he said.
“We need to look at the nutrigenomics side of the coin,” D’Adamo told attendees at the event which took place last week in Tucson, AZ. “We need to look at the impact that food has on our genes. At the same time we need to understand the influence our genes have on how we respond to certain foods.”
Variants in the methylation cycle
For instance, D’Adamo pointed to the profound influence of the MTHRF gene, which governs the production of a critical rate limiting enzyme in the body’s methylation cycle. Normal methylation cycles depend upon adequate levels of vitamin B12 as well as other key nutrients such as folate, riboflavin, B6, niacin, magnesium and zinc. With normal amounts of folate and B12 the body is able to convert homocysteine into glutathione and SAMe (S-adenosylmethionine). An abnormality in the MTHRF gene can impair this crucial cycle, D’Adamo said.
“You could have people walking around with suboptimal levels of vitamin B12, which could increase the risk of cardiovascular disease, cognitive dysfunction, and other conditions,” he said.
There’s another gene that has a role in this dance, D’Adamo said. Variants in the gene FUT2 are associated with varying blood levels of B12, he said. While FUT2 takes center stage, there are other dancers in the chorus, too.
“While FUT2 has the biggest influence on B12, there is some evidence that the genes CD320 and NMT2 are also involved in B12 levels,” he said.
Examples with vitamin C, alpha carotene and lycopene
Another example is the gene SLC23A1, which encodes one of two transporters for vitamin C in the body. This a critical function for human health, because Homo sapiens are unusual when it comes to this vitamin, D’Adamo said.
“Humans are one of the few mammals that do not make their own vitamin C. If there are abnormalities in that gene, it would make sense that levels would be low even if a person was taking in what was recommended,” he said.
In other instances of how genes affect nutrient status, D’Adamo said recent work his team has done with a population of Amish farmers (whose lifestyle eliminated some confounders) shows the association of the CAPN2/CAPN8 genetic locus on serum alpha-carotene levels. Another recent study of his shows how a common variant in the SETD7 gene predicts serum lycopene concentrations.
Delivering on the promise
Putting it all together, D’Adamo said having some basic genetic information would go a long way toward understanding how a particular individual incorporates nutrients into their system. Without this information, a dietary supplement formulation is really just a best-guess type situation. This works well enough for most consumers. And most if not all of the ingredients commonly found in dietary supplements can be consumed at higher than absolutely necessary levels without fear of toxicity. But that’s not really delivering on the promise that personalized nutrition marketers are proffering, he said.
“What I don’t want to see are shady operators making over the top claims for expensive supplements,” he said.
