Omega-3 fatty acids are a type of fat essential in human nutrition and physiology. They are easily acquired from common food sources to include cold water fish such as salmon and sardines, meat from grass fed animals, eggs, and plant sources to include walnuts, flaxseeds, and black raspberry.
Despite this dietary abundance, pharmaceutical and food processing companies have been producing and marketing Omega-3 supplements to capitalise on its supposed health and wellness benefits. One of these benefits centres on the effect of Omega-3 supplementation in improving memory performance.
It is important to take note of the fact that there are three types of Omega-3 fatty acids essential in human nutrition and physiology. These are alpha-linolenic acid or ALA found in plant oils, and eicosapentaenoic acid or EPA and docosahexaenoic acid or DHA commonly found in marine food sources.
Omega-3 and improving memory performance
There is a considerable number of literatures that tried linking Omega-3 supplementation with improved memory performance. One of these is conducted at the University of Pittsburgh led by Rajesh Narendarn. The study concluded that increasing Omega-3 intake with fish oil supplements can improve the working memory of young adults.
The study of Narendarn et al involved recruiting healthy young men and women from different ethnic backgrounds to subject them under an experiment that involved boosting their Omega-3 intake with supplements for a period of six months. Note that the experiment involved taking 950 mg of EPA and 750 mg of DHA a day.
The participants were also subjected under a series of outpatient procedures before and after the experiment to determine further that they were indeed healthy while under observation. Moreover, they underwent working memory tests to measure and compare their cognitive performance before and after the experiment.
Results of the experiment revealed a significant improvement in the working memory of the participants. Interestingly, their memory performance has further improved despite having a normal cognitive health.
There are also other studies supporting the role of Omega-3 fatty acids in improving brain health, especially cognitive performance. For instance, the study by Rahul Agrawal and Fernando Gomez-Pinilla found out that Omega-3 supplementation can partially counteract that deleterious effects of high sugar consumption in the metabolic functions of brain. Furthermore, their study also concluded that a deficiency in Omega-3 can exacerbate the dysfunctions in insulin receptor signaling and cognition.
Researchers I. Bauer et al also carried a study somewhat similar to the study of Narendarn et al. Their study focused on determining which between EPA and DHA has a pronounced effect in improving cognitive performance among young adults.
Through a double-blind, counterbalanced, crossover design that involved a 30-day washout period between two different 30-day supplementations period, the study revealed that under EPA-rich supplementation, the brain of participants worked less hard while achieving better cognitive performance. In addition, DHA-rich supplementation appears to be less effective than EPA-rich supplementation in enhancing neurocognitive functioning.
But the study by Steve Connor et al revealed that that memory cells in the hippocampus could communicate better with each other and better relay messages when DHA levels in that region of the brain were higher. Note that their study involved observing and analyzing the brain of laboratory animal models.
Effects of Omega-3 supplements in adult cognitive performance
The studies of Narendarn et al and Bauer et al have concluded that Omega-3 supplementation in young adults results in an improve cognitive performance, including working memory. When it comes to older adults, however, several studies have concluded otherwise.
Researchers Ammann et al have found no association between higher levels of red blood cell EPA and DHA and age-associated cognitive decline in a cohort of older, dementia-free women. Note that this study involved following a total of 2,157 women with normal cognitive functioning enrolled in a clinical trial of postmenstrual hormone therapy for a median period of 5.9 years. These participants were subjected under an annual cognitive testing to determine cognitive measures at baseline and assess cognitive change overtime.
Emma Sydenham, Alan D. Dangour, and Wee-Shiong Lim also conducted a review study that involved collecting data from a total of 3,536 participants from previous clinical trials lasting between six to 40 months. The entire participants were grouped into two—with the first group taking Omega-3 supplement while the second group taking a placebo. The result of the review revealed that there was no benefit of taking the Omega-3 supplement over the placebo. In addition, participants who took Omega-3 supplements did not score better in standard mental state examinations or in memory and verbal fluency tests than those who received the placebo.
There was also an earlier study conducted by a team of researchers headed by Yvonne Freund-Levi. Accordingly, their study concluded that Omega-3 supplementation may slowdown cognitive decline in some patients with very mild case of Alzheimer’s disease. But this positive effect does not appear in more advanced case of Alzheimer’s disease
Dosage may also play an important role. A review study by Abdul-Razak Abubakari, Mohammad-Mahdi Naderali, and Ebrahim K. Naderali that involved using data from 12 randomized controlled dial for a systematic review and meta-analysis method concluded that Omega-3 supplementation may be beneficial in preventing memory decline at lower doses.
Considerations for future studies about Omega-3 and memory performance
The effectiveness of taking Omega-3 supplements for improving memory performance remains unclear primarily because there is a discord in available literatures. Currently, there is some evidence that Omega-3 supplementation can improve the working memory and cognitive functions of younger adults. However, for older adults, several studies concluded that there are no direct relationships between supplementation and improved memory performance, or in completely preventing memory decline.
Researchers Sydenham et al nonetheless concluded that the longer term effects of omega-3 fatty acids on cognitive decline and dementia need to be explored in further studies, particularly in people with low intakes of omega-3 fatty acids in their diet. Freund-Levi and her team also mentioned that there findings should also not serve as a basis for general recommendations for treatment of Alzheimer’s disease with dietary DHA-rich fish oil preparations.
Further details of the study of Narendarn et al are found in the article “Improved Working Memory but No Effect on Striatal Vesicular Monoamine Transporter Type 2 after Omega-3 Polyunsaturated Fatty Acid Supplementation” published in the journal PLOS One. Details of the study of Bauer et al are in the article “Omega-3 supplementation improves cognition and modifies brain activation in young adults” published in the journal Human Psychopharmacology.
Details of the study of Connor et al are in the article “DHA supplementation enhances high-frequency, stimulation-induced synaptic transmission in mouse hippocampus” published in the journal Applied Physiology, Nutrition, and Metabolism. The study of Agrawal and Gomez-Pinilla is detailed further in the article “‘Metabolic syndrome’ in the brain: deficiency in omega-3 fatty acid exacerbates dysfunctions in insulin receptor signalling and cognition” published in The Journal of Physiology.
Results of the study of Amman et al are in the article “Omega-3 fatty acids and domain-specific cognitive aging” published in the article Neurobiology. The study of Sydenham et al is detailed further in the article “Omega 3 fatty acid for the prevention of cognitive decline and amnesia” published in the journal Sao Paulo Medical Journal. Further details of the study of Freund-Levi et al are found in the article “ω-3 Fatty Acid Treatment in 174 Patients with Mild to Moderate Alzheimer Disease: OmegAD Study a Randomized Double-blind Trial” published in the journal JAMA Neurology. The study of Abubakari is detailed further in the article “Omega-3 fatty acid supplementation and cognitive function: are smaller dosages more beneficial?” published in International Journal of General Medicine.