Feed Your Genes: How Genetics Influence Our Response to Food
By Victoria Rea
26 May 2021
A new study from the Department of Human Health and Nutritional Sciences has found that genetics have an important influence on how our bodies respond to dietary fats.
Dr. David Mutch studies nutrigenetics, a field focused on how our genetic make-up affects our response to nutrients in the foods we eat. His lab is particularly interested in desaturases, a family of enzymes that inserts double bonds into fatty acids. One of these desaturases converts saturated fatty acids (SFAs) into monounsaturated fatty acids (MUFAs).
MUFAs are linked to many health benefits including reduced risk of heart disease and stroke. They also play a role in insulin regulation and controlling blood sugar levels. However, due to genetic variations in desaturase genes, there is evidence suggesting that some people may not produce MUFAs as effectively as others.
“Studies around the world have suggested that people who aren’t good at producing MUFAs may be at greater risk of inflammation, which can contribute to diabetes and other diseases,” says Mutch. “So our question became, if people have certain genetic variants that make them less able to produce MUFAs on their own, do MUFAs in the diet help rescue the situation?”
With their expertise in desaturase enzymes, genetics and nutrition, Mutch’s lab was perfectly positioned to investigate how the metabolic benefits of a MUFA-rich oil are influenced by genetic variants in the stearoyl-CoA desaturase gene, or SCD for short. These variants are known as a single nucleotide polymorphism, or SNP, meaning there is a difference in just a single molecule in the DNA sequence.
Mutch, along with recent MSc graduate Dana Lowry and undergraduate researcher Michael Roth, took advantage of blood samples previously collected from 101 people with obesity participating in a large clinical trial looking at the health benefits of canola oil, which is a MUFA-rich dietary oil. They used the samples to compare fasting blood glucose levels in participants with genetic variants and those without, following consumption of oil that was either high in MUFA (canola oil) or SFA (control).
The team found that individuals with a specific SNP in the SCD gene showed increases in blood glucose after consuming the control oil, while individuals without the gene variant showed a decrease in blood glucose. In other words, the SNP was associated with an unfavourable metabolic response in participants consuming the control oil.
However, when both groups of participants consumed high MUFA canola oil, they experienced similar decreases in blood glucose.
The results suggest that individuals who may have naturally low MUFA production as a result of the SCD variant could benefit from consuming dietary MUFAs - a very relevant finding considering that one-third of individuals of European descent carry this variant.
Using an individual’s genetic information to guide dietary recommendations is a booming field, but Mutch notes that studies like this need to be reproduced to have clinical relevance.
“Now comes the next phase. Can somebody reproduce the same results with this particular SNP in a totally different cohort of individuals? That would make this work really impactful.”
The clinical trial that provided the samples was a randomized cross-over double-blind study led by collaborators at the University of Manitoba, and the SNP analysis was statistically rigorous, which is exactly the type of high-quality study that is needed to continue to advance the field of nutrigenetics, and ultimately inform clinicians.
Mutch believes we are already moving in that direction.
“Dietitians are now starting to offer these services to clients. People are interested in this kind of personalized approach to nutrition, and they can go to direct-to-consumer companies to get genetic information about themselves. It’s exciting.”
This study was funded by the Canola Council of Canada.
Read the full study in The British Journal of Nutrition.
Read about other CBS Research Highlights.