A breaking new study shows 92% of its participants had a genotype which caused them to have higher triglyceride levels when taking fish oil supplements. But how can that be when the long-standing claims on fish oil and triglycerides have told us something very different?
Thousands – if not millions – of articles and web pages recommend adding fish oil to your daily diet. They aren’t pulling their evidence out of thin air; multiple research studies back their claims.
They link fish oil consumption to reduced risks of conditions affecting the heart, blood vessels, brain, and skin.
One widely accepted claim is that fish oil balances our “good” – HDL (high-density lipoprotein) cholesterol and the “bad” LDL (low-density lipoprotein) cholesterol that contributes to cardiovascular diseases.
Research has also focused on the connection between fish oil and triglycerides (TAGs), a type of blood lipid (fat). When we overeat, our bodies convert the extra calories into triglycerides and store them in our fat cells.
High TAG levels raise our risk of cardiovascular disease. But many persuasive studies have indicated that fish oil supplementation lowers triglycerides.
Fish Oil and Triglycerides Research: a Closer Look
For example, a 2011 study from the University of South Dakota’s Sanford School of Medicine found that 3.4 grams a day of fish oil reduce plasma TAGs by 25 to 50 percent.
And children consuming 4 grams of fish oil each day experienced an antithrombotic (blood-thinning) effect that “slightly” reduced their TAG levels, according to this 2014 study published in the Journal of Pediatrics. However, it did not affect their LDL particles.
Overall, however, the research is inconclusive. Why would the short-term studies show a lowering effect, while the most recent large cohort study shows the opposite result?
The large study, published in March 2021, challenges the claims of fish oil’s triglyceride-lowering power.
Genes, Fish Oil and Triglycerides: An Unexpected Outcome
Researchers from the University of Georgia decided to test the hypothesis that our genetic makeup influences whether we’ll benefit from fish oil supplementation.
To identify which genomic factors affect blood lipid levels, they conducted a genome-wide association study (GWAS) among participants of the UK Biobank.
The study’s first stage included 73,962 of the UK Biobank’s Caucasian genetic participants in the Biobank UK. The second stage gathered samples from 7,284 white participants in the ARIC (Atherosclerosis Risk in Communities) group study.
The researchers looked at four fats. All were biomarkers (measurable indicators of biological changes) of cardiovascular health:
and triglycerides (TAGs).
They divided the samples into two groups, those from about 11 thousand people taking fish oil supplements and the rest from participants not taking them.
And that’s how they discovered that the results differed depending on a person’s genes!
Their goal was to observe fish oil’s association with two main “A” and “G” genes. Participants had one of three genotypes:
- AA (homozygous individuals)
- AG (heterozygous individuals)
- GG (homozygous individuals)
The majority – 92.1 percent (74,504) were AA. Another 7.7 percent (6,250) were AG. Only 0 .1 percent (107) were GG.
What were the fish oil and triglycerides outcomes according to genotype?
- The AA group (the overwhelming majority!) had higher TAGs than those not taking fish oil supplements.
- The AG group had lower TAGs than those not taking fish oil supplements.
- The GG group was so small that the researchers decided not to consider their TAG levels.
This remarkable finding only adds to the confusion surrounding claims that fish oil supplements are “heart-healthy.”
The researchers identified fish oil supplementation’s impact on continuous fat traits. Multiple genes affect these traits, which include our rate of weight gain and body fat distribution.
But the presence of minor regions (alleles) in a gene could change the fish oil and triglycerides interaction.
Studies have shown that fish oil is beneficial in treating high triglycerides and that its omega-3 polyunsaturated fatty acids affect HDL-C particles.
However, its overall effects on cardiometabolic lipid risk markers remain unclear. This uncertainty arose because few studies have considered genetic variants.
The University of Georgia study showed that fish oil supplementation reduces TAGs for people with the AG genotype.
But for anyone with the AA genotype (much more common), it can backfire and raise TAGs.
Perhaps fish oil supplementation interacts with the genetic locus in GJB2 in these individuals. Such an interaction affects the risk of cardiovascular disease in different ways.
The researchers concluded that fish oil supplements could lower triglycerides in people with the AG genotype, but seem to have the opposite effect in those with the AA genotype.
I’m not sure why studies on fish oil and triglycerides differ, but if we are going to take supplements, it’s high time we start getting our omega-3s from the same place fish get them – algae.