12 January - 20 June 2016

Omega-3 fatty acid and seafood consumption may benefit those at risk of dementia

A study published in the journal Neurology has investigated consumption of seafood and long chain n-3 fatty acids with changes in 5 cognitive areas. It also investigates the APOE ꜫ4 gene, a gene which is associated with risk of dementia, on whether it modifies any association.

Previous studies have identified the importance of seafood and n-3 fatty acids in the prevention of dementia and global cognitive functioning, however few have examined the effect on specific cognitive areas.  A study published in the journal Neurology has investigated consumption of seafood and long chain n-3 fatty acids with changes in 5 cognitive areas. It also investigates the APOE ꜫ4 gene, a gene which is associated with risk of dementia, on whether it modifies any association.

Van de Rest et al. followed 915 people, dementia free, mean age 81.4 years, for an average of five years who were involved in the Rush Memory Aging Project. The participants completed annual food frequency questionnaires reporting intake of 144 food items including 4 seafood items: tunafish sandwich, fish sticks/fish cakes/fish sandwich, fresh fish as a main dish, and shrimp/lobster/crab.  Fish oil supplement consumption was also noted.  At each annual evaluation the participants complete 21 cognitive tests - 19 measured decline in global cognition and 5 in specific areas (episodic memory, semantic memory, working memory, perceptual speed and visuospatial ability).  Van de Rest et al. also investigated the effect of smoking behaviour, alcohol consumption, cognitive activity and exercise participation, blood pressure amongst others.  APOE genotype was measured using DNA from blood samples.

The scientists report compared to those in the lowest group, the highest intake group of long-chain n-3 fatty acid intake, were mainly physically active men, APOE ꜫ4 carriers, and were less likely to have a history of diabetes, hypertension or stroke.  They also had a higher baseline scores on some of the cognitive areas. Participants in the higher seafood consumption group ate an average two seafood meals per week. Those in the lower group ate an average of 0.5 meals per week.

The study found that people who ate one or more seafood meals per week had reduced rates of decline in the semantic memory (memory of verbal information) and perceptual speed (the ability to quickly compare letters, objects and patterns) compared to those who consumed less. The study did not demonstrate slower decline in global cognition.  Dietary intake of α-linoleic acid and food sources of n-3 fatty acids were not associated with any measure of cognitive decline in the overall group. However those who consumed fish oil supplement (161 participants) had slower rates of decline in global cognitive measures and in episodic memory compared with non-consumers. 

On investigation of APOE ꜫ4 (178 participants) status “the relation may be more pronounced” in individuals who had this genotype. Slower rates of decline were seen in global cognition and in multiple cognitive domains with weekly seafood consumption and with moderate to high long chain n-3 fatty acid intake from food. α linoleic acid was also associated with slower cognitive decline in this group.  

In discussion the scientists note APOE ꜫ4 is reported to increase brain neuro-inflammation and deposition of amyloid beta plaque.  DHA is known to have anti-inflammatory and antioxidant properties, and previous mice studies have indicated that the effect of APOE ꜫ4 have been prevented by a DHA-rich diet.  Van de Rest et al. report that the interaction is not fully understood, although it has been suggested those with the APOE ꜫ4 carrier may have “poor brain protection and repair mechanisms” and this may make them more beneficial to long chain n-3 fatty acid. 

RSSL's Lipids Laboratory has expertise in all aspects of fat analysis and fatty acid profiling, including the determination of omega-3 and omega-6 fatty acids. For more information please contact Customer Services on +44 (0) 118 918 4076 or email enquiries@rssl.com

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