DHA is also required for maintenance of normal brain function in adults. The inclusion of plentiful DHA in the diet improves learning ability, whereas deficiencies of DHA are associated with deficits in learning. DHA is taken up by the brain in preference to other fatty acids. The turnover of DHA in the brain is very fast, more so than is generally realized.When DHA is used by the body, some of it converts to another essential fatty acid, EPA.¹ The two acids have many similarities (both are found in fish oils), but are not identical; ideally, a proper diet contains adequate amounts of both fatty acids.

DHA is essential for visual and neurological development in infants.² Supplementation appears to be helpful for premature infants’ brain development.³ Supplementation is especially important for premature infants who are not breastfed, as breastmilk has DHA and formula does not.⁴ Deficiencies are most often found in formula-fed premature infants.

DHA’s usefulness does not end with infancy, however. It has also been shown to decrease aggressiveness in adolescent males.⁵ Others who show DHA deficiencies include Alzheimer’s patients⁶ and children with Attention Deficit Disorder (ADD).⁷ It appears especially effective in the treatment of arthritis, due to its anti-inflammatory properties.⁸

DHA, when taken in conjunction with EPA, appears to lower blood pressure.⁹

DHA also appears to slow the growth of leukemia cells.¹⁰

Natural Sources: Food sources: Eggs, Organ meats, Mackerel, Salmon, Sardines, Tuna.

Useful in treatment of:
Heart Disease Prevention: There is some evidence that fish oil can help prevent heart disease, but it is not definitive. One study followed individuals for 3 to 5 years and found that fish oil could significantly reduce the risk of death from heart attack, and that it was more effective for this purpose than vitamin E.¹¹ However, this was not a double-blind study. Fish oil can lower serum triglycerides¹² and appears to modestly raise the levels of HDL ("good") cholesterol.^13,14 Additionally, it may help the heart by "thinning" the blood and by reducing blood levels of homocysteine.¹⁵ Blood clots play a major role in heart attacks, and homocysteine is an amino acid that appears to raise the risk of heart disease.

Neurologic Disease: Decreases in DHA in the brain are associated with cognitive decline during aging and with onset of sporadic Alzheimer disease.¹⁶

Psychiatric Disease: DHA levels in red blood cells have been correlated with depression in humans¹⁷. A small study has shown that fish oil can produce striking benefits in bipolar disease, preventing relapse and improving emotional state.¹⁸

Rheumatoid Arthritis: The omega-3 fatty acids in fish oil can help reduce the symptoms of rheumatoid arthritis, according to 12 double-blind placebo-controlled studies.¹⁹ However, unlike some conventional treatments, fish oil probably does not slow the progression of rheumatoid arthritis.

Raynaud's Phenomenon: Very high dosages of fish oil have been found to reduce the severe finger and toe responses to cold temperatures that occur in Raynaud's phenomenon.^20,21

Lupus: One small double-blind placebo-controlled crossover study compared placebo against daily doses of EPA (20 g) from fish oil. Of the 17 individuals completing the trial, 14 showed improvement when taking EPA, while only 4 did so when treated with placebo.²²

Psoriasis: Some studies have shown improvement in the symptoms of psoriasis with EPA, however the size of the patches did not change.23 It may not be useful in severe psoriasis. ²⁴

Osteoporosis: When taken along with calcium, essential fatty acids may also help prevent osteoporosis. In one study, the treated groups had denser bones and fewer fractures than the placebo group.²⁵ Similar results were seen in another study of 40 women.²⁶

Menstrual Pain: Regular use of fish oil may reduce the pain of menstrual cramps. In one 4-month crossover study of 42 young women, participants received a daily dose of 6 g of fish oil, providing 1,080 mg of EPA and 720 mg of DHA daily, and then switched to placebo. A second group was treated in the reverse order. The results showed that these young women experienced significantly less menstrual pain while they were taking fish oil.²⁷

Recommended Dosage: 500 to 3000 mg daily, in divided doses. Should be taken with Vitamin E.

Contraindications: May cause elevated blood sugar, especially in diabetics.²⁸Higher doses may also cause an increase in LDL cholesterol.²⁹ Patients concerned about either condition should speak to a nutritional specialist before taking DHA supplements. Since it thins the blood, those taking blood thinners such as coumadin should only use fish oil under the supervision of a physician.

References:
¹Conquer 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;126:3032–39.
²Gibson RA, Neumann MA, Makrides M. Effect of dietary docosahexaenoic acid on brain composition and neural function in term infants. Lipids 1996;31:177S–81S.
³Werkman SH, Carlson SE. A randomized trial of visual attention of preterm infants fed docosahexaenoic acid until nine months. Lipids 1996;31:91–97.
⁴Crawford MA, Costeloe K, Ghebremeskel K, et al. Are deficits of arachidonic and docosahexaenoic acids responsible for the neural and vascular complications of preterm babies? Am J Clin Nutr 1997;66(suppl):1032S–41S.
⁵Hamazaki T, Sawazaki S, Itomura M, Asaoka E, et al. The effect of docosahexaenoic acid on aggression in young adults. A placebo-controlled double-blind study. J Clin Invest 1996;97:1129–33.
⁶Soderberg M, Edlund C, Kristensson K, et al. Fatty acid composition of brain phospholipids in aging and in Alzheimer’s disease. Lipids 1991;26:421–25.
⁷Stevens LJ, Zentall SS, Deck JL, et al. Essential fatty acid metabolism in boys with attention-deficit hyperactivity disorder. Am J Clin Nutr 1995;62:761–68.
⁸Altman R, Gray R. Inflammation in osteoarthritis. Clin Rheum Dis 1985;11:353.
⁹Morris MC, Sacks F, Rosner B. Does fish oil lower blood pressure? A meta-analysis of controlled trials. Circulation 1993;88:523–33.
¹⁰Effect of docosahexaenoic acid on rate of differentiation of HL-60 human leukemia. Cancer Res, 24(1):3252-8 1989 Jun 15
¹¹Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico. Lancet 354(9177): 447–455, 1999.
¹²Harris WS. N-3 fatty acids and serum lipoproteins: human studies. Am J Clin Nutr 65(suppl.): 1645S–1654S, 1997.
¹³Cobiac L, Clifton PM, and Abbey M. Lipid, lipoprotein, and hemostatic effects of fish vs fish-oil n-3 fatty acids in mildly hyperlipidemic males. Am J Clin Nutr 53: 1210–1216, 1991.
¹⁴Harris WS. N-3 fatty acids and serum lipoproteins: human studies. Am J Clin Nutr 65(suppl.): 1645S–1654S, 1997.
¹⁵Dyerberg, J. N-3 fatty acids and coronary artery disease. Potentials and problems. Omega-3, Lipoproteins, and Atherosclerosis 27: 251–258, 1996.
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¹⁷Peet M; Murphy B; Shay J; Horrobin D. Depletion of omega-3 fatty acid levels in red blood cell membranes of depressive patients. Biol Psychiatry 1998 Mar 1;43(5):315-9
¹⁸Stoll AL, et al. Omega 3 fatty acids in bipolar disorder: a preliminary double-blind, placebo-controlled trial. Arch Gen Psychiatry 56(5): 407–412, 1999.
¹⁹James MJ and Cleland LG. Dietary n-3 fatty acids and therapy for rheumatoid arthritis. Semin Arthritis Rheum 27: 85–97, 1997.
²⁰DiGiacomo RA, Kremer JM, and Shah DM. Fish-oil dietary supplementation in patients with Raynaud's phenomenon: a double-blind, controlled, prospective study. Am J Med 86: 158–164, 1989.
²¹ Ringer TV, et al. Fish oil blunts the pain response to cold pressor testing in normal males. Abstract. J Am Coll Nutr 8: 435, 1989.
²²Walton AJ, Snaith ML, and Locniskar M. Dietary fish oil and the severity of symptoms in patients with systemic lupus erythematosus. Ann Rheum Dis 50: 463–466, 1991.
²³Bittiner SB, Tucker WF, and Cartwright I. A double-blind, randomised, placebo-controlled trial of fish oil in psoriasis. Lancet 1: 378–380, 1988.
²⁴Soyland E, Funk J, Rajka G, et al. Effect of dietary supplementation with very-long-chain n-3 fatty acids in patients with psoriasis. N Engl J Med 328: 1812–1816, 1993.
²⁵Kruger MC, et al. Calcium, gamma-linolenic acid (GLA) and eicosapentaenoic acid (EPA) supplementation in osteoporosis. Osteoporosis Int 6(suppl. 1): 250, 1996.
²⁶van Papendorp DH, Coetzer H, and Kruger MC. Biochemical profile of osteoporotic patients on essential fatty acid supplementation. Nutr Res 15: 325–334, 1995.
²⁷Harel Z, Biro FM, Kottenhahn RK, et al. Supplementation with omega-3 polyunsaturated fatty acids in the management of dysmenorrhea in adolescents. Am J Obstet Gynecol 174: 1335–1338, 1996.
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