Oily fish and fish oil have a high content of the two omega-3 fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), that are important for our brain, nervous system, intelligence, and mental health. Modern diets, however, are to blame for our lack of omega-3. A team of scientists from England has found that supplementation with EPA-rich fish oil for 26 weeks improves mental acuity and reaction time in healthy, young adults. This was not the case with DHA-rich oil fish oil, on the other hand. The scientists were surprised to find that EPA is more important than DHA for these cognitive skills.
The human brain contains omega-3 and omega-6 fatty acids that provide integrity to the neuronal network. Omega-3 fatty acids also work together in a biochemical interplay with omega-6 fatty acids and it is vital to get the different fatty acid types in the proper ratio.
Earlier studies have shown that an increased intake of the omega-3 fatty acids, EPA and DHA, is associated with improved cognitive functions throughout life. Omega-3 fatty acids are something we get from oily fish and fish oil in particular. However, the intake of omega-3 from marine sources in many Western countries has decreased tremendously due to altered eating habits and the widespread use of unnatural animal fodder, something which affects the entire food chain.
To date, most studies have focused on DHA because it is present in rather large concentrations in the central nervous system and because of its role in cell structure and signaling. Nonetheless, some smaller studies of recent date suggest that supplementation with EPA may also be relevant for cognitive functions in healthy adults. It is possible that EPA’s effects are caused by improved neuronal efficacy and increased oxygen turnover in the prefrontal cortex.
For the first time ever, a team of scientists from Northumbria University and Southampton University in England decided to investigate if supplements of EPA and DHA given to young, healthy adults with low dietary intake of these omega-3 fatty acids could improve their cognitive skills.
The details and surprising results of the study
The scientists recruited 310 healthy adults aged 25-49 years to participate in a randomized, controlled study. One group was given a fish oil supplement with more DHA than EPA (900 mg DHA and 270 mg EPA). Another group was given a fish oil supplement that primarily contained EPA (360 mg DHA and 900 mg EPA). Finally, a third group was given an olive oil placebo and served as a control group.
The study lasted 26 weeks. At baseline and at the end of the study, the participants were asked to complete a series of memory exercises. The scientists also measured the oxygen turnover (hemoglobin oxygenation) in the prefrontal cortex by using near-infrared spectroscopy (NIRS). The study indicated that those participants who got EPA-rich fish oil had a significantly better memory score than those given a fish oil that primarily contained DHA. In fact, the DHA-rich fish oil did not seem to improve neither memory or reaction time compared with placebo. According to the researchers, this study helps understand the omega-3 fatty acids’ influence on mental health and the study results were important for the following three reasons:
- It was carried out on young, healthy adults – not children or seniors
- The study only used 1,200 mg of EPA and DHA for a six-month period
- The study found that fish EPA-rich oil was more effective than DHA-rich fish oil for improving cognitive functions
These observations may be of use to scientists who wish to study this area in the future. Although the brain contains more DHA than EPA, it still looks as if EPA plays a vital role for cognitive functions, and to a greater extent than previously thought. The scientists also assume that the increased oxygen turnover in the prefrontal cortex may be linked to the increased efficacy. The new study is published in Journal of Clinical Nutrition.
Oily fish or fish oil supplements
The majority of Danes fail to meet the official recommendations for fish intake that suggest eating at least 350 mg of fish per week, of which 200 grams should be from oily fish that are particularly rich in EPA and DHA. A problem that is worth taking into consideration is that farmed fish do not contain optimal amounts of omega-3 because they are fed with unnatural fodder. It is better to eat free-range salmon and herring from clean waters and to avoid predator fish like tuna that tends to accumulate heavy metals.
The following table lists the content of EPA and DHA in different types of fish. If you aim to get around 900 mg of EPA daily (like in the study above), it can be done by eating around 60 grams of smoked mackerel or a little over 100 grams of free-range salmon.
When purchasing fish oil supplements, it is always advisable to look at the label to see how much EPA and DHA is in the product. Fish oil based on free fatty acids has faster and better absorption than fish oil based on triglycerides or esters. Also make sure that the fish oil is within the threshold levels with regard to peroxide count and environmental toxins.
|Cod liver oil||11||12|
|Mackerel, in tomato sauce||0.6||1.1|
|Cod roe, raw||0.2||0.4|
Stephen Daniells. EPA-rich fish oils boost cognitive performance for healthy, young adults: RCT. NUTRAingredients.com 2021
M.J. Patan, et al. Supplementation with oils rich in eicosapentaenoic acid, but not docosahexaenoic acid, improves global cognitive function in healthy, young adults: results from randomized controlled trials. The American Journal of Clinical Nutrition. 2021
Frida - Parametre (fooddata.dk)
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