Docosahexaenoic acid (DHA)

Overview

Docosahexaenoic acid (DHA) is an omega-3 fatty acid. It is found in cold water fatty fish, such as salmon. It is also found in fish oil supplements, along with eicosapentaenoic acid (EPA). Vegetarian sources of DHA come from seaweed.

Your body needs DHA for the proper functioning of your brain as an adult, and for the development of your nervous system and visual abilities during the first 6 months of life. In addition, omega-3 fatty acids are part of a healthy diet that helps lower risk of heart disease.

Our bodies naturally produce small amounts of DHA, but we must get the amounts we need from our diet or supplements. Most people in the Western world do not get enough omega-3 fatty acids in their diet.

Uses

Attention-Deficit Hyperactivity Disorder (ADHD)

Because omega-3 fatty acids are needed for children's brains to develop properly, researchers have examined whether fish oil might reduce ADHD symptoms. So far, results have been mixed. One study showed fish oil might help, but many patients dropped out of the study before it was completed.

Depression

Although some studies have shown that fish oil reduces symptoms of depression, it isn't clear whether DHA alone has the same effect. Other studies suggest it may be EPA which has the positive effect on depression.

Heart Disease

Fish oil appears to have positive effects on existing heart disease. It also may lower the risk for developing heart disease. Omega-3 fatty acids found in fish oil help lower triglycerides (fats in the blood), lower blood pressure, reduce the risk of blood clots, improve the health of arteries, and reduce the amount of arterial plaque, which narrows arteries and causes heart disease. The American Heart Association recommends eating fish, particularly fatty fish, at least two times a week. Fatty fish include salmon, herring, lake trout, sardines and albacore tuna. People with existing heart disease may need fish oil supplements in addition to adding more fish to their diet. Ask your doctor if fish oil supplements would be right for you.

Infant Development

DHA plays a crucial role in the growth and development of the central nervous system as well as visual functioning in infants.

Rheumatoid Arthritis

Several small studies indicate that fish oil may help reduce symptoms and inflammation associated with rheumatoid arthritis. However, it does not stop joint damage from getting worse.

Menstrual Pain

Fish oil appears to reduce the pain of menstrual cramps when taken on a regular basis (not just when menstruating).

Raynaud Syndrome

Several studies show that high doses (12 g) of fish oil can reduce sensitivity to cold in the fingers and toes of people with Raynaud syndrome. Doses this high should be taken only under a doctor's supervision.

Lupus

Two small studies suggested that fish oil reduced fatigue and joint pain associated with lupus.

Dietary Sources

DHA is found in cold water fatty fish, including salmon, tuna (bluefin tuna have up to five times more DHA than other types of tuna), sardines, shellfish, and herring.

Although some of these fish contain low levels of mercury, the Food and Drug Administration has found that consuming several servings of fish each week poses no risk to healthy people and conveys many health benefits.

Women who are pregnant or planning to become pregnant should avoid king mackerel, shark, swordfish, and tilefish. They should also limit consumption of white albacore tuna to under 6 oz. per week.

High-quality fish oil supplements made by manufacturers who test for mercury and other toxins do not pose the same risk of mercury contamination. Read labels carefully and check for purity, or ask your doctor to help you find the best quality DHA supplement.

For infants, breast milk from a mother who eats a healthy diet contains significant amounts of DHA. Infant formula may or may not have any DHA. Read labels carefully to find a brand that does.

Available Forms

DHA is available as a supplement in two common forms:

• Fish oil capsules, which contain both DHA and EPA (eicosapentaenoic acid), another omega-3 fatty acid
• DHA from algae, which contains no EPA

How to Take It

Pediatric

• Babies who are breastfed should get enough EPA if their mothers are getting enough EPA in her diet.

Adult

• Most studies have used 1,000 - 2,500 mg of DHA per day.
• In the diet: 2 - 3 servings of fatty fish per week, which corresponds to 1,250 mg EPA and DHA per day.
• Fish oil supplements: 3,000 - 4,000 mg standardized fish oils per day. Read the label to check levels of DHA and EPA, which are not the same as mg of fish oil. People who take blood-thinning medication, such as warfarin (Coumadin) or aspirin, or people who have hemophilia should check with their doctors to determine a safe dose.
• Pregnant women: 200 mg DHA per day
• DHA supplements from algae: 200 mg per day

Some fish oil supplements also contain vitamin E to maintain freshness.

Supporting Research

Demonty I, Chan YM, Pelled D, Jones PJ. Fish-oil esters of plant sterols improve the lipid profile of dyslipidemic subjects more than do fish-oil or sunflower oil esters of plant sterols. Am J Clin Nutr. 2006 Dec;84(6):1534-42.

Dunstan JA, Simmer K, Dixon G, Prescott SL. Cognitive assessment at 21/2 years following fish oil supplementation in pregnancy: a randomized controlled trial. Arch Dis Child Fetal Neonatal Ed. 2008 Jan;93(1):F45-50. [Epub ahead of print]

Fatty fish consumption and ischemic heart disease mortality in older adults: The cardiovascular heart study. Presented at the American Heart Association's 41st annual conference on cardiovascular disease epidemiology and prevention. AHA. 2001.

Harper CR, Jacobson TA. The fats of life: the role of omega-3 fatty acids in the prevention of coronary heart disease. Arch Intern Med. 2001;161(18):2185-2192.

Innis SM. Dietary omega 3 fatty acids and the developing brain. Brain Res. 2008 Sep 9. [Epub ahead of print]

Iso H, Rexrode KM, Stampfer MJ, Manson JE, Colditz GA, Speizer FE et al. Intake of fish and omega-3 fatty acids and risk of stroke in women. JAMA. 2001;285(3):304-312.

Jacobson TA. Role of n-3 fatty acids in the treatment of hypertriglyceridemia and cardiovascular disease. Am J Clin Nutr. 2008 Jun;87(6):1981S-90S.

Jeschke MG, Herndon DN, Ebener C, Barrow RE, Jauch KW. Nutritional intervention high in vitamins, protein, amino acids, and omega-3 fatty acids improves protein metabolism during the hypermetabolic state after thermal injury. Arch Surg. 2001;136:1301-1306.

Juhl A, Marniemi J, Huupponen R, Virtanen A, Rastas M, Ronnemaa T. Effects of diet and simvistatin on serum lipids, insulin, and antioxidants in hypercholesterolemic men; a randomized controlled trial. JAMA. 2002;2887(5):598-605.

Kris-Etherton P, Eckel RH, Howard BV, St. Jeor S, Bazzare TL. AHA Science Advisory: Lyon Diet Heart Study. Benefits of a Mediterranean-style, National Cholesterol Education Program/American Heart Association Step I Dietary Pattern on Cardiovascular Disease. Circulation. 2001;103:1823.

Leaf A. Historical overview of n-3 fatty acids and coronary heart disease. Am J Clin Nutr. 2008 Jun;87(6):1978S-80S.

Mabile L, Piolot A, Boulet L, Fortin LJ, Doyle N, Rodriquez C, et al. Moderate intake of omega-3 fatty acids is associated with stable erythrocyte resistance to oxidative stress in hypertriglyceridemic subjects. Am J Clin Nutr. 2001;7494):449-456.

Mori TA. Omega-3 fatty acids and hypertension in humans. Clin Exp Pharmacol Physiol. 2006 Sep;33(9):842-6. Review.

Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA. 2006 Oct 18;296(15):1885-99. Review.

Oken E, Radesky JS, Wright RO, Bellinger DC, Amarasiriwardena CJ, Kleinman KP, et al. Maternal fish intake during pregnancy, blood mercury levels, and child cognition at age 3 years in a US cohort. Am J Epidemiol. 2008 May 15;167(10):1171-81.

Olsen SF, Secher NJ. Low consumption of seafood in early pregnancy as a risk factor for preterm delivery: prospective cohort study. BMJ. 2002;324(7335): 447-451.

Politi P, Cena H, Comelli M, Marrone G, Allegri C, et al. Behavioral effects of omega-3 Fatty Acid supplementation in young adults with severe autism: an open label study. Arch Med Res. 2008 Oct;39(7):682-5.

Saravanan P, Davidson NC, Schmidt EB, Calder PC. Cardiovascular effects of marine omega-3 fatty acids. Lancet. 2010 Aug 14;376(9740):540-50. Review.

Stanke-Labesque F, Molière P, Bessard J, Laville M, Véricel E, Lagarde M. Effect of dietary supplementation with increasing doses of docosahexaenoic acid on neutrophil lipid composition and leukotriene production in human healthy volunteers. Br J Nutr. 2008 Oct;100(4):829-33. Epub 2008 Feb 28.

Sun Q, Ma J, Campos H, Rexrode KM, Albert CM, Mozaffarian D, Hu FB. Blood concentrations of individual long-chain n-3 fatty acids and risk of nonfatal myocardial infarction. Am J Clin Nutr. 2008 Jul;88(1):216-23.

Alternative Names

Introduction

Possible Interactions

Blood pressure medication -- DHA may lower blood pressure, so it could make the effects of prescription blood pressure medication stronger.

Anticoagulants (blood thinners) -- EPA in fish oil supplements may increase bleeding time, so fish oil could make the effects of these drugs stronger. The same does not appear to be true of DHA alone. Blood thinners include warfarin (Coumadin) and aspirin.

Diabetes medications -- Theoretically, fish oil supplements may lower blood sugar levels and could make effects of diabetes drugs stronger. If you have diabetes, talk to your doctor before taking fish oil.

Aspirin -- Combined with aspirin, fish oil could help treat some forms of heart disease. However, this combination may also increase the risk of bleeding. Talk to your doctor to see if this combination is right for you.

Cyclosporine -- Omega-3 fatty acids may reduce some of the side effects of cyclosporine, which is often used to stop rejection in transplant recipients. Talk to your doctor before adding any new herbs or supplements to the medication you already take.

Precautions

Fish oil capsules contain both DHA and EPA. Supplements containing EPA may not be recommended for infants or small children because they upset the balance between DHA and EPA during early development. Pregnant women should talk to their doctor before taking fish oil supplements.

Fish oil capsules may cause minor side effects, such as loose stools, stomach upset, and belching.

They may prolong bleeding time slightly. If you take blood-thinning medication, talk to your doctor before taking fish oil.