Should You Take Fish Oil? It Depends

James R. Hood
James R. Hood

Think fish oil supplements are good for you? Well, they might be. But then again, they might not be. Now, researchers have developed a way to tell whether you have the genetic make-up to produce the results you’re looking for.

Consumers spend $1 billion a year on fish oil supplements in hopes that the omega-3 fatty acids in the supplements will help lower their triglycerides, a type of fat that is implicated in cardiovascular disease. But there has been no proof that the supplements are actually beneficial, which led a University of Georgia scientist to take a closer look.

The study, led by Kaixiong Ye and published in PLOS Genetics, focused on fish oil (and the omega-3 fatty acids it contains) and its effect on triglycerides, a type of fat in the blood and a biomarker for cardiovascular disease.

“We’ve known for a few decades that a higher level of omega-3 fatty acids in the blood is associated with a lower risk of heart disease,” said Ye, assistant professor of genetics at UGA, in a news release. “What we found is that fish oil supplementation is not good for everyone; it depends on your genotype. 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.”

Ye’s study was published in PLOS Genetics.

About the study

Ye’s team examined four blood lipids (fats)–high-density lipoprotein, low-density lipoprotein, total cholesterol and triglycerides–that are biomarkers for cardiovascular disease. The data for their sample of 70,000 individuals was taken from UK Biobank, a large-scale cohort study collecting genetic and health information from half a million participants.

The team divided the sample into two groups, those taking fish oil supplements (about 11,000) and those not taking fish oil supplements. Then they performed a genome-wide scan for each group, testing for 8 million genetic variants to compare. After running over 64 million tests, their results revealed a significant genetic variant at gene GJB2.

Individuals with the AG genotype who took fish oil decreased their triglycerides. Individuals with the AA genotype who took fish oil slightly increased their triglycerides.

Determining your genotype is not as far-fetched as it sounds, thanks to direct-to-consumer genetic testing companies. Companies may not report that specific genetic variant yet, but a tech-savvy consumer should be able to download the raw data and look at the specific position to discover the genotype, according to Ye. The ID for the variant is rs112803755 (A>G).

Earlier studies

The study’s findings may also shed light on previous trials, most of which found that fish oil provides no benefit in preventing cardiovascular disease.

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

Now that Ye has identified a specific gene that can modify an individual’s response to fish oil supplementation, his next step will be directly testing the effects of fish oil on cardiovascular disease.

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

James R. Hood

Jim is a publishing entrepreneur and journalist. He founded ConsumerAffairs in 1998 and earlier was the founder of Zapnews, after holding executive posts at the Associated Press.