One study that’s been conducted on DHA looked at its effects on cognitive function in older adults. The study, published in the American Journal of Clinical Nutrition, involved a randomized, double-blind, placebo-controlled trial with a sample size of 485 adults over the age of 70.
Participants were given either a placebo or a supplement containing 900 mg of DHA per day for 24 months. At the end of the study, researchers found that the DHA group had significantly better cognitive function than the placebo group, particularly in areas related to memory and learning.
Specifically, the study reported improvements in:
- Verbal Memory: The DHA group had significantly better scores on the Hopkins Verbal Learning Test (HVLT) – a test of verbal memory that measures the ability to learn and recall a list of 12 words – compared to the placebo group. The DHA group recalled an average of 0.64 more words from the list of 12 words than the placebo group (p=0.03).
- Processing Speed: The DHA group had significantly faster completion times on the Trail Making Test (TMT) – a test of executive function that requires participants to connect numbered circles on a sheet of paper in sequence as quickly as possible – compared to the placebo group. The DHA group completed the TMT task an average of 9.9 seconds faster than the placebo group (p=0.04).
- Selective Attention: The DHA group had significantly better scores on the Stroop Test – a test of selective attention and processing speed that requires participants to name the color of ink in which words are written while ignoring the meaning of the words – compared to the placebo group. The DHA group was able to name the colors of the words on the Stroop Test an average of 2.6 seconds faster than the placebo group (p=0.02).
It’s worth noting that the effect sizes of these differences were generally small to moderate, but still statistically significant. These findings suggest that DHA supplementation may have a modest but measurable impact on cognitive function in older adults, particularly in areas related to memory, processing speed, and selective attention.
Another study, published in the Journal of the American College of Cardiology, looked at the effects of DHA on cardiovascular health. This study involved a meta-analysis of 13 randomized controlled trials with a total of over 120,000 participants.
The researchers found that DHA supplementation was associated with a lower risk of cardiovascular disease, particularly in people who had already had a heart attack or were at high risk for heart disease.
Specifically, they found 3 major impacts:
- Risk of Fatal Cardiovascular Disease: The meta-analysis found that DHA supplementation was associated with a 9% lower risk of fatal cardiovascular disease compared to placebo
- Risk of Coronary Heart Disease Events: DHA supplementation was also associated with a 6% lower risk of coronary heart disease (CHD) events, including non-fatal heart attacks and CHD deaths
- Effects in High-Risk Populations: The beneficial effects of DHA supplementation on cardiovascular health were particularly pronounced in people who had a history of heart disease or were at high risk for heart disease. In this group, DHA supplementation was associated with a 19% lower risk of major cardiovascular events
A third study, published in the British Journal of Nutrition, looked at the effects of DHA on eye health. This study involved a randomized, double-blind, placebo-controlled trial with 33 participants over the age of 60.
Participants were given either a placebo or a supplement containing 840 mg of DHA and 270 mg of eicosapentaenoic acid (EPA) per day for 12 weeks. At the end of the study, researchers found that the DHA and EPA group had significantly better retinal blood flow than the placebo group, indicating improved eye health.
These are just a few examples of the many scientific studies that have been conducted on DHA and its health benefits. If you’re interested in incorporating DHA into your diet, you can find it in fish like salmon, tuna, and sardines, or in supplement form.
However, in untested/unverified supplements the levels of DHA can differ, and so too can they differ in natural food sources such as fish – depending on the fish’s own diet and environment.
So the most stable, guaranteed form of DHA comes in the form of third-party verified supplements – and we’ve linked to a couple of recommendations for high DHA content fish oils, that are third party tested and verified, in the description of the video below.
Also, in terms of reliable food forms of DHA – the best one is Schizochytrium sp. This is a type of algae and it’s actually commonly used as the base source of DHA for dietary supplements and infant formula because it has a high DHA content, up to 40-50% of its total oil content, and is easy to grow in large quantities. Schizochytrium sp. is a marine microalga that naturally synthesizes high levels of DHA to adapt to the low-temperature and high-pressure environment of deep-sea water.
So there you have it – we can see that DHA has some significant and credible evidence behind it for various health benefits.
If you’d like to test your fish oil or DHA supplement to verify the DHA content – please choose the ‘core ingredient’ test service in our shop.