Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is essential for the proper functioning of our brains as adults, and for the development of our nervous system and visual abilities during the first six months of life. Lack of sufficient DHA may be associated with impaired mental and visual functioning as well as attention-deficit hyperactivity disorder (ADHD) in children. Low levels have also been associated with depression and Alzheimer's disease in adults. Our bodies naturally produce some DHA, but in amounts too small and irregular to ensure proper biochemical functioning. Therefore, preformed DHA must be consumed in the diet through foods such as cold water fatty fish or in supplement form in order to assure an adequate supply.

• Attention-Deficit Hyperactivity Disorder (ADHD): Research has identified the impact of low DHA levels on ADHD (and possibly other learning, health, and sleep problems) in children. However, studies have not yet been conducted to determine whether supplementation with DHA is useful for the prevention or treatment of these conditions.

• Depression: Insufficient DHA may be related to increasing rates of depression in adults. More research is warranted to confirm the possible association between DHA and depression and to investigate whether DHA supplements may be of benefit in depressed patients.

• Heart Disease: DHA supplementation enhanced the DHA status of vegetarians and favorably influenced cholesterol levels. Because people with diabetes often develop heart disease, some diabetics may benefit from omega-3 fatty acid supplementation (including DHA).

• Infant Development: DHA plays a crucial role in the growth and development of the central nervous system as well as visual functioning in infants. Nutrition experts have issued recommendations that pregnant and lactating women should consume 300 mg per day of DHA. Adequate intakes for infants on formula diets should be 0.35% DHA.

• Other Conditions: Some experts believe that omega-3 fatty acids (in the form of eicosapentaenoic acid (EPA) and DHA) may reduce inflammation and promote wound healing in burn victims and may also prove to be valuable in preventing colon cancer or treating it in its early stages. In addition, obese people who follow a weight loss program achieve better control over their blood sugar and cholesterol levels when fatty fish containing EPA and DHA is a staple in the diet.

DHA is found in cold water fatty fish including wild salmon (not farm raised), tuna (bluefin tuna have up to five times more DHA than other types of tuna), mackerel, sardines, shellfish, and herring. Some organ meats such as liver and brain are also a good source of this essential fatty acid, and eggs provide some DHA, but in lower amounts. For infants, breast milk contains significant amounts of DHA, while infant formula often has none (see above for the amount that should be present).

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 extracted from algae (which contains no EPA)

Recommendations for adequate intake put forth by the International Society for the Study of Fatty Acids and Lipids (ISSFAL) appear below.

Pediatric

• Infants that are breastfed should receive sufficient amounts of DHA if the mother has an adequate intake of this fatty acid.
• ISSFAL recommends that formula for infants contain 0.35% DHA. 

Adult

• Pregnant and lactating women, per ISSFAL, should consume 300 mg/day of DHA
• The adequate daily intake of DHA for other adults should be at least 220 mg/day 
• Therapeutic recommendations from diet: 2 to 3 servings of fatty fish per week, which corresponds to 1,250 mg EPA and DHA per day 
• Fish oil supplements: 3,000 to 4,000 mg standardized fish oils per day, which is the equivalent of 2 to 3 servings of fatty fish per week
• Algal-derived DHA supplements: 200 mg per day 

Some commercial products may also contain vitamin E to maintain freshness. For supplements, follow the directions on product labels for both dosage information and storage requirements; some products require refrigeration. Do not use products beyond their expiration date.

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. This suggests that pregnant women should also be cautious about taking fish oil supplements. These effects may be avoided by using DHA supplements derived from algae sources, which do not contain EPA.

Fish oil capsules may be associated with side effects such as loose stools, abdominal discomfort, and unpleasant belching. In addition, they may prolong bleeding time slightly; therefore, people with bleeding disorders or those taking blood-thinning medications should discuss the use of fish oil capsules with their healthcare providers before taking them. Consumption of fish oil supplements may also increase antioxidant requirements in the body. Taking extra vitamin E along with these supplements may be warranted; again, please consult your healthcare provider.

In combination with aspirin, omega-3 fatty acids could be helpful in the treatment of some forms of coronary artery disease. Consult your healthcare provider about whether this combination would be appropriate for you if you have coronary artery disease.

Omega-3 fatty acids may reduce some of the side effects associated with cyclosporine therapy, which is often used to reduce the chances of rejection in transplant recipients. Consult your healthcare provider before adding any new herbs or supplements to your existing medication regimen.

In an animal study, omega-3 fatty acids protected the stomach against ulcers induced by reserpine and nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin. Consult your healthcare provider before using omega-3 fatty acids if you are currently taking these medications.

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