Health Benefits of Long-chain Omega-3 Fatty Acids (DHA and EPA)
DHA is important for pregnant and nursing women
DHA is one of the crucial building blocks of human brain tissue. Omega-3 fatty acids are structural components of cell membranes — DHA specifically accumulates in the cell membranes of the retina, brain, and nervous system. Adequate levels of DHA throughout life are important for vision and learning.1 The developing baby’s only source of DHA for beginning to build brain tissue is its mother’s dietary intake. Early in life, DHA is supplied via the placenta and from breast milk. During the last trimester of pregnancy and first two years of childhood, DHA is especially important for vision and brain development.2 Maintaining adequate DHA levels during pregnancy is believed to benefit the child’s cognitive development.3 Studies have shown improved intelligence scores of breast fed children whose mothers took DHA supplements during pregnancy and nursing.4 Similarly, the results of three randomized controlled trials in 2009 showed that babies given supplemental DHA in formula scored higher on a problem solving test at 9 months of age than babies given control formula.5 DHA supplementation also reduces the risk of preterm birth — a factor known to be associated with compromised cognitive development in the infant and maternal depression.6
Since pregnant women are urged to limit fish consumption because of the potential harm from mercury contamination to the brain of the developing baby, supplemental DHA is a safe alternative.7
Omega-3 fatty acids for prevention/treatment of ADHD
Insufficient DHA has been linked to a number of childhood cognitive and developmental disorders such as ADHD, dyslexia, and autism spectrum disorders.8,9 Supplementation with omega-3s, especially in combination with certain omega-6 fatty acids, has been found to improve behavior and ADHD symptoms.2,10-12
DHA for prevention of Alzheimer’s disease and cognitive decline
Low DHA intake and low levels of DHA in the blood are associated with age-related cognitive decline and Alzheimer’s disease. DHA or EPA+DHA supplements have been found to improve learning and memory in mild cognitive impairment, but not in already established Alzheimer’s disease. The important message from these studies is that omega-3 supplements are most effective when taken preventively.13-15 Maintaining adequate DHA stores throughout life, as well as eating a diet rich in natural plant foods, is necessary for preventing the late life occurrence of these age-related cognitive deficits.
Omega-3 fatty acids for prevention of cardiovascular disease
Fish consumption has been linked to decreased risk of death from coronary heart disease and sudden cardiac death. This decreased risk has been attributed to beneficial effects of omega-3 fatty acids, and similar results have been seen with algae-based omega-3 supplements.16
- Decreased electrical excitability of heart muscle cells, which prevents arrhythmias that can lead to sudden cardiac death
- Modulation of inflammatory processes leading to decreased clotting, reducing the risk of heart attack
- Slowing the growth of atherosclerotic plaque by reducing inflammation
- Enhancing endothelial cell function, mildly reducing blood pressure
- Improves serum lipids17,18
- Increasing arterial elasticity, which lowers pulse pressure19,20
A recent review of the literature has determined that 250 mg of long-chain omega-3 fatty acids per day is an effective dose for reducing cardiovascular risk. Intake of at least 250 mg/day was associated with a 35.1% reduced risk of sudden cardiac death and a 16.6% reduced risk of total fatal coronary events compared to intake of less than 250 mg/day.21
Omega-3 fatty acids for preventing and treating depression, especially postpartum depression
Low omega-3 status may increase vulnerability to depression. Extraction of mothers’ DHA stores by their babies is thought to be responsible for many cases of postpartum depression. Long-chain omega-3 fatty acids can affect the metabolism of depression-related neurotransmitters (serotonin, norepinephrine, and dopamine), and their anti-inflammatory effects are thought to ameliorate depression symptoms as well.2,22,23 High dose omega-3 supplements are also used to treat depression, and their therapeutic effects are due mostly to EPA rather than DHA, according to a recent meta-analysis.24
Omega-3 fatty acids for preventing Parkinson’s disease
Recent scientific findings show diets rich in omega-3 fatty acids, in particular DHA (docosahexaenoic acid), have a protective effect against neurodegenerative diseases like Parkinson’s disease. Studies in animals clearly show that supplementation of DHA can alter brain DHA concentrations and have protective effects on brain cells that can reduce the risk of Parkinson's.25
My experience over the last twenty years of counseling hundreds of vegan patients struck me with a peculiar oddity: I saw a number of male elderly vegans that developed Parkinson’s disease (males convert short chain omega-3 from greens, walnuts and flax less efficiently to DHA than do females). The striking thing was that when I drew their blood levels for DHA, they were not just deficient, but their DHA was almost non-existent. I observed a significant, severe deficiency of DHA in elderly vegan males. Most often these were men who ate a very healthy vegan diet with sufficient nuts and seeds and no junk food. This led me to think that DHA deficiency may be a contributory factor for Parkinson’s.
Animal studies support this idea. One recent study examined mice which were exposed to two diets; one group was fed a diet with DHA and other omega-3 fatty acids; while the other group was given ordinary food, lacking DHA. After a period of time they were given a dose of a chemical that causes the same damage to the brain as Parkinson’s disease. The mice on the DHA diet seemed to be immune to the effects of the chemical, whereas the mice that ate ordinary food developed symptoms of the disease. DHA concentrations increased in the brains of the mice that had been given omega-3 supplementation, but concentrations of other omega-3s (ALA and EPA) were similar in both groups of mice. This result suggested that the protective effect against Parkinson’s indeed came from DHA.26
My experience confirms that for DHA levels sufficient to maintain brain health throughout life, a healthy diet (even with plenty of ALA-rich foods) simply may not be enough. This may be more important for males as they age. DHA deficiency carries dangerous risks and supplementation is the sensible choice.
1. Higdon J: Essential Fatty Acids. In An Evidence-Based Approach to Dietary Phytochemicals. New York, NY: Thieme; 2006: 78-99
2. Kidd PM: Omega-3 DHA and EPA for cognition, behavior, and mood: clinical findings and structural-functional synergies with cell membrane phospholipids. Altern Med Rev 2007;12:207-227.
3. Ryan AS, Astwood JD, Gautier S, et al: Effects of long-chain polyunsaturated fatty acid supplementation on neurodevelopment in childhood: a review of human studies. Prostaglandins Leukot Essent Fatty Acids 2010;82:305-314.
4. Helland IB, Smith L, Saarem K, et al: Maternal supplementation with very-long-chain n-3 fatty acids during pregnancy and lactation augments children's IQ at 4 years of age. Pediatrics 2003;111:e39-44.
5. Drover J, Hoffman DR, Castaneda YS, et al: Three randomized controlled trials of early long-chain polyunsaturated Fatty Acid supplementation on means-end problem solving in 9-month-olds. Child Dev 2009;80:1376-1384.
6. Oken E, Belfort MB: Fish, fish oil, and pregnancy. JAMA 2010;304:1717-1718.
7. Koletzko B, Cetin I, Brenna JT: Dietary fat intakes for pregnant and lactating women. Br J Nutr 2007;98:873-877.
8. Schuchardt JP, Huss M, Stauss-Grabo M, et al: Significance of long-chain polyunsaturated fatty acids (PUFAs) for the development and behaviour of children. Eur J Pediatr 2010;169:149-164.
9. Stevens LJ, Zentall SS, Deck JL, et al: Essential fatty acid metabolism in boys with attention-deficit hyperactivity disorder. Am J Clin Nutr 1995;62:761-768.
10. Sinn N, Bryan J, Wilson C: Cognitive effects of polyunsaturated fatty acids in children with attention deficit hyperactivity disorder symptoms: a randomised controlled trial. Prostaglandins Leukot Essent Fatty Acids 2008;78:311-326.
11. Sinn N, Bryan J: Effect of supplementation with polyunsaturated fatty acids and micronutrients on learning and behavior problems associated with child ADHD. J Dev Behav Pediatr 2007;28:82-91.
12. Transler C, Eilander A, Mitchell S, et al: The impact of polyunsaturated fatty acids in reducing child attention deficit and hyperactivity disorders. J Atten Disord 2010;14:232-246.
13. Yurko-Mauro K: Cognitive and cardiovascular benefits of docosahexaenoic acid in aging and cognitive decline. Curr Alzheimer Res 2010;7:190-196.
14. Yurko-Mauro K, McCarthy D, Rom D, et al: Beneficial effects of docosahexaenoic acid on cognition in age-related cognitive decline. Alzheimers Dement 2010.
15. Quinn JF, Raman R, Thomas RG, et al: Docosahexaenoic acid supplementation and cognitive decline in Alzheimer disease: a randomized trial. JAMA 2010;304:1903-1911.
16. Doughman SD, Krupanidhi S, Sanjeevi CB: Omega-3 fatty acids for nutrition and medicine: considering microalgae oil as a vegetarian source of EPA and DHA. Curr Diabetes Rev 2007;3:198-203.
17. Conquer JA, Holub BJ: Supplementation with an algae source of docosahexaenoic acid increases (n-3) fatty acid status and alters selected risk factors for heart disease in vegetarian subjects. J Nutr 1996;126:3032-3039.
18. Geppert J, Kraft V, Demmelmair H, et al: Microalgal docosahexaenoic acid decreases plasma triacylglycerol in normolipidaemic vegetarians: a randomised trial. Br J Nutr 2006;95:779-786.
19. Kris-Etherton PM, Harris WS, Appel LJ: Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Arterioscler Thromb Vasc Biol 2003;23:e20-30.
20. Nestel P, Shige H, Pomeroy S, et al: The n-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid increase systemic arterial compliance in humans. Am J Clin Nutr 2002;76:326-330.
21. Musa-Veloso K, Binns MA, Kocenas A, et al: Impact of low v. moderate intakes of long-chain n-3 fatty acids on risk of coronary heart disease. Br J Nutr 2011.
22. Ramakrishnan U, Imhoff-Kunsch B, DiGirolamo AM: Role of docosahexaenoic acid in maternal and child mental health. Am J Clin Nutr 2009;89:958S-962S.
23. Stahl LA, Begg DP, Weisinger RS, et al: The role of omega-3 fatty acids in mood disorders. Curr Opin Investig Drugs 2008;9:57-64.
24. Martins JG: EPA but not DHA appears to be responsible for the efficacy of omega-3 long chain polyunsaturated fatty acid supplementation in depression: evidence from a meta-analysis of randomized controlled trials. J Am Coll Nutr 2009;28:525-542.
25. Calon F, Cole G: Neuroprotective action of omega-3 polyunsaturated fatty acids against neurodegenerative diseases: evidence from animal studies. Prostaglandins Leukot Essent Fatty Acids 2007;77:287-293.
26. Bousquet M, Saint-Pierre M, Julien C, et al: Beneficial effects of dietary omega-3 polyunsaturated fatty acid on toxin-induced neuronal degeneration in an animal model of Parkinson's disease. FASEB J 2008;22:1213-1225.