High DHA levels cut mortality risk by 21%, study shows

A new large-scale, longitudinal study has reaffirmed that high levels of DHA in tissues can reduce the risk of all-cause mortality significantly. The paper used data from a large study cohort in the UK. 

The new research was published earlier this month in the journal Mayo Clinic Proceedings. It was the work of a group of noted omega-3s researchers associated with St. Luke’s Mid America Heart Institute in Kansas City, Mo., the University of Denver and the Fatty Acid Research Institute in Sioux Falls, S.D. 

The researchers used data culled from the UK Biobank. This is a large-scale biomedical database and research resource containing de-identified genetic, lifestyle and health information and biological samples from half a million UK participants. 

Large scale and long term 

The researchers used data from 117,702 subjects with baseline plasma DHA levels and 12.7 years of follow-up between April 2007 and December 2021. 

The study focused on DHA levels because in 2007 that was the only fatty acid that could be measured with the technology in use at the time by the databank’s administrators. 

In recent years, omega-3 levels have been assessed by reference to the Omega-3 Index, a concept jointly developed by William S. Harris (one of the study’s authors) and German researcher Clement von Schacky. This measures the amount of omega-3 fatty acids in red blood cell tissues, expressed as a percentage, from lows in the 3% range up to more than 8%. OmegaQuant, a company that Harris founded, provides this testing service in the U.S. and other markets. 

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The study cohort was made up of older individuals who were about 57 years old at intake and generally overweight (average body mass index greater than 27). They were nevertheless relatively healthy, and overall, the UK Biobank participants are somewhat healthier than the overall UK population. The study cohort was overwhelmingly white. 

The longest follow-up visit took place slightly more than 14 years from the start, with the average follow-up time being 12.7 years. During that time, 8,622 of the original 177,702 participants died. Of those deaths 1,831 were related to cardiovascular disease, 4,183 were cancer-related deaths, and 2,609 people died from other causes. 

Highest quintile had 21% lower mortality risk 

As with other studies of this type, the cohort was divided up into quintiles in terms of DHA levels. The highest quintile corresponded to an omega-3 index of 8%. One to two servings of fatty fish (such as herring, sardines or salmon) per week are recommended by health authorities to achieve higher omega-3 levels. 

However, it has been proven that omega-3 levels are boosted just as effectively by taking a supplement. More than one half of the members of the highest quintile in the study were taking an omega-3 supplement. 

The researchers found the risk of overall mortality was 21% lower for the highest quintile as opposed to the lowest.  

“This analysis shows highly significant inverse associations between DHA and all mortality endpoints assessed. These findings support the American Heart Association Science Advisory recommendation to consume at least one to two seafood meals/week,” the researchers concluded. 

Harris said the result, while not groundbreaking or unexpected, nevertheless adds to the already impressive body of research backing omega-3s.  

“This report from over 117,000 people in the UK Biobank confirms previous work from the FORCE consortium showing that a low blood omega-3 levels are associated with increased risk for premature death, not only from cardiovascular disease and from cancer, but for all-cause mortality,” Harris told Natural Products Insider. “This is further evidence that higher omega-3 levels help promote greater longevity.”