Genes may determine if fish oil supplements are good or bad for you

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A compelling study investigating the relationship between genetics, diet and heart health is claiming the cardiovascular benefits often linked to taking fish oil supplements may only be apparent in individuals of a certain genotype. The associational study suggests that in the future, nutritional recommendations may be optimized by taking into account a person’s unique genetic composition.

In recent years a growing body of research has begun to question the long-standing advice recommending omega-3 fish oil supplements as beneficial for those at high risk of cardiovascular disease. Several large-scale meta-analyses found little benefit to taking the popular supplement and a phase 3 clinical trial testing a purified concentrated form of one particular fatty acid found in fish oil was discontinued after interim data revealed no benefits.

A new study, published in the journal PLOS Genetics, set out to investigate whether a novel gene-diet interaction could account for the apparent discordancy in prior research. A genome-wide association study was conducted, encompassing over 70,000 UK Biobank participants.

One specific genetic variant that influences a gene called GJB2 was identified in the study as being significantly associated with reduced triglycerides in those subjects taking fish oil supplements.

While this beneficial variant, dubbed AG, led to triglyceride reductions in those taking fish oil supplements, a different variant, dubbed AA, was associated with slightly higher triglyceride levels in those taking the supplements.

“What we found is that fish oil supplementation is not good for everyone; it depends on your genotype,” says Kaixiong Ye, lead on the new study. “If you have a specific genetic background, then fish oil supplementation will help lower your triglycerides. But if you do not have that right genotype, taking a fish oil supplement actually increases your triglycerides.”

Of course, the researchers do note the limitations inherent to this kind of associational study. Although a plausible mechanism can be traced to this gene and its effect on blood lipids, more focused work will be needed to understand how fish oil supplementation could interact with these genetic variants and influence cardiovascular health.

However, Ye does say this novel associational finding could help explain why a large number of previous studies investigating fish oil supplements and cardiovascular health have led to conflicting findings.

“One possible explanation is that those clinical trials didn’t consider the genotypes of the participants,” notes Ye. “Some participants may benefit, and some may not, so if you mix them together and do the analysis, you do not see the impact.”

If validated by further research, this kind of gene-diet interaction lends credence to the nascent field of precision nutrition. The idea is there may be no “one-size-fits-all” recommendation for dietary strategies and in the future nutritional advice could be specifically tailored to individual subjects based on a variety of physiological factors, including genetics.

“Personalizing and optimizing fish oil supplementation recommendations based on a person’s unique genetic composition can improve our understanding of nutrition, and lead to significant improvements in human health and well-being,” concludes Ye.

The new study was published in the journal PLOS Genetics.

Source: University of Georgia

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