DHA & Cognitive Function

The Benefits of DHA in Adult Health

Docosahexaenoic acid, DHA, is an omega-3 fatty acid that is found throughout the body. More specifically, it is a major structural fat in the brain and eyes and a key component of the heart. A growing body of research continues to support the role that DHA plays in maintaining good health throughout every stage of life. Below are research highlights from studies examining the role of DHA in adult health.

• DHA is the predominant omega-3 fatty acid found in the brain, representing about 97% of all omega-3 fatty acids in the brain. It is especially concentrated in the region of the brain that is responsible for complex thinking skills.
• DHA is concentrated in the retina and membranes of the eye. It represents 93% of all omega-3 fatty acids in the eye.
• Low levels of DHA in red blood cells have been associated with cognitive decline in healthy elderly people.1
• Findings from a large observational study indicate that intake of the omega-3 fatty acid, DHA, and especially the ratio of omega-3 to omega-6 fatty acids, independent of childhood IQ, is important in the health of cognitive function later in life.2
• Observational studies indicate that a high intake of fish, a good source of DHA, may be associated with a reduced risk for developing Alzheimer's dementia3 and a slowing of normal, age-related, cognitive decline.4
• One study showed that people with the highest levels of plasma DHA (the top 20% of those in the study) had a significant (47%) reduction in the risk of developing dementia from any cause. After nine years of follow-up, subjects with the highest levels of plasma DHA were less likely to develop Alzheimer's disease.5
• Results of a Swedish cohort study suggest that n-3 fatty acid, especially DHA, are positively associated with peak bone mineral density in the total body and spine in healthy young men.6
• DHA is important for cardiovascular health. There does not appear to be significant differences in triglyceride-lowering benefits between DHA only and DHA + EPA combination products when dosing is based on DHA.7
• Evidence from observational and randomized controlled trials suggests a possible role of dietary long-chain omega-3 fatty acids, including DHA, in protection against ischemic stroke, the most common type of stroke in the U.S. and a leading cause of long-term disability.8,9

1 Heude B, et al. Cognitive decline and fatty acid composition of erythrocyte membranes - The EVA Study. Am J Clin Nutr, 2003. 77:803-8.

2 Whalley LJ, et al. Cognitive aging, childhood intelligence, and the use of food supplements: possible involvement of n-3 fatty acids. Am J Clin Nutr, 2004. 80:1650-7.

3 Morris MC, et al. Consumption of fish and n-3 fatty acids and risk of incident Alzheimer disease. Arch Neurol, 2003. 60:940-6.

4 Morris MC, et al. Fish consumption and cognitive decline with age in a large community study. Arch Neurol, 2005. 62:1849-53.

5 Schaefer E, et al. Plasma phosphatidylcholine docosahexaenoic acid content and risk of dementia and Alzheimer disease: the Framingham Heart Study. Arch Neurol, 2006. 63:1545-50.

6 Hogstrom M, et al. n-3 Fatty acids are positively associated with peak bone mineral density and bone accrual in healthy men: the NO2 Study. Am J Clin Nutr, 2007. 85:803-7.

7 Schwellenbach LJ, et al. The triglyceride-lowering effects of a modest dose of docosahexaenoic acid alone versus in combination with low dose eicosapentaenoic acid in patients with coronary artery disease and elevated triglycerides. J Am Coll Nutr, 2006. 25:480-85.

8 He KA, et al. The puzzle of dietary fat intake and risk of ischemic stroke: a brief review of epidemiologic data. J Am Diet Assoc, 2007. 107:287-95.

9 Wang C, et al. n-3 Fatty acids from fish or fish-oil supplements, but not from alpha-linolenic acid, benefit cardiovascular disease outcomes in primary-and secondary –prevention studies: a systematic review. Am J Clin Nutr, 2006. 84:5-17.