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25 January 2017 - Nutraingredients - Omega-3s linked to better cognitive function in mildly impaired older people

Stephen Daniells

Daily supplements of omega-3 fatty acids may improve measures of cognitive function, including memory and perceptual speed, says a new study from China.

The benefits were observed with daily EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) doses of 720 mg and 480 mg, respectively, in people with a mean age of 71 with mild cognitive impairment (MCI).

“The results of this study suggest that n-3 PUFA [omega-3 polyunsaturated fatty acids] supplementation may have positive benefits in individuals with MCI and may also be beneficial in primary prevention in people with MCI,” wrote researchers from Zhengzhou University, The Center for Disease Control and Prevention of China, and the Tianjin Institute of Health and Environment Medicine in Nutrients .

A reasonable goal

Commenting independently on the study's findings, Harry Rice, PhD, VP of regulatory & scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED), told us: “Since individuals with MCI, compared to cognitively normal individuals, have an increased risk of developing dementia, delaying further cognitive deterioration is a reasonable goal and one that these investigators achieved in the current study.

“Given the small sample size, coupled with results that conflict with some past research, further research is definitely needed and acknowledged by the coauthors.

“Future research should focus on recruitment of Apolipoprotein-ε4 (APOE-ε4) carriers since APOE-ε4 is a major genetic risk factor for cognitive decline and Alzheimer's Disease,” said Dr Rice.

Study details

The researchers recruited 86 people with MCI and randomly assigned them to receive daily omega-3 supplements (with an EPA: DHA ratio of 3:2) or placebo (olive oil) for six months. While they state that there is no consensus on the appropriate omega-3 dose, they noted that both the European Food Safety Authority and the UN’s Food and Agriculture Organization recommend a range between 0.25grams and 2 grams per day for the elderly.

The omega-3 group showed significantly improved scores on the Basic Cognitive Aptitude Tests (BCAT), which measure cognitive function.

In addition, significant improvements were recorded for perceptual speed, space imagery efficiency, and working memory in the omega-3 group, while no improvements were recorded for mental arithmetic efficiency or recognition memory.

Men and women appeared to respond differently to the omega-3 supplement regimen, said the researchers with omega-3s leading to significant improvements in perceptual speed, space imagery efficiency, working memory, and total BCAT scores in men, while women experienced significant beneficial effects for perceptual speed, space imagery efficiency, and total BCAT scores. 

Mechanism(s) of action

The researchers noted that there are several potential mechanisms of action to explain the benefits: “First, n-3 PUFAs constitute more than 30% of the membrane phospholipid composition, regulating membrane structure, fluidity, and signal-transduction.

“In addition, n-3 PUFAs modulate gene expression patterns that facilitate BDNF-mediated synaptic plasticity, influence B-vitamin or homocysteine pathways, and activate energy-generating mechanisms involved in glucose and lipid metabolism. Moreover, n-3 PUFAs may protect cognitive function by modulating the immune response to amyloid-beta.”