Health & Wellbeing

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

Genes may determine if fish oi...
Several gene variants were associated with how well fish oil supplements seemed to lower a person's triglyceride levels in a new study
Several gene variants were associated with how well fish oil supplements seemed to lower a person's triglyceride levels in a new study
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Several gene variants were associated with how well fish oil supplements seemed to lower a person's triglyceride levels in a new study
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Several gene variants were associated with how well fish oil supplements seemed to lower a person's triglyceride levels in a new study

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

4 comments
paul314
It seems that a lot of randomized studies may run into this kind of effect. Of course, unless you know the genotype and other details of the person you're attempting to treat, the average result is all you have to go on.
Douglas Rogers
I thought blood thinning was the main effect of fish oil.
toni24
It would have been better if they had at least listed the demographics or racial heritage of those who have the beneficial genes from and the racial demographic of those who find the fish oil a detriment. At least then, we could be tested for the genes
Karmudjun
I didn't need this study to know which one of my patients benefited from Omega-3 supplements. But then, when seeing patients I actually listen to them and can only hope they listen to me.
@Douglas Rogers - many supplements can increase bleeding tendencies, fish oil is just one. I personally don't recommend it for CV patients on a 'blood thinner' that reduces clotting (or increases bleeding tendencies). Always discuss supplement use with YOUR physician or health care provider.