DHA (Docosahexaenoic acid)
Article courtesy of Donna Hargrove, D.O., Nutrition Editor
Not all fats are bad. Eating too many saturated fats and trans fats is not good for your health. But polyunsaturated fats, particularly omega-3 fatty acids, have been shown to promote good health from infancy through adulthood.
What is Docosahexaenoic Acid (DHA)?
DHA is a long-chain omega-3 fatty acid found throughout the body, especially in the brain and eyes. It is present naturally in specific fatty fish such as salmon, trout, mackerel, sardines and tuna, as well as breast milk.
Many people confuse DHA with its shorter-chain cousin alpha-linolenic acid (ALA). ALA is an essential fatty acid found mainly in flaxseed, walnuts, canola oil and a few other plant foods. It has different health effects from DHA.
DHA for a Healthy Pregnancy and a Healthy Child
DHA is important for proper brain and eye development, especially during pregnancy and infancy. Beginning in the last trimester of pregnancy and continuing through the first 2 years of life and beyond, DHA levels in the brain rapidly increase.
Several studies have shown that infants with higher blood levels of DHA score better on tests measuring their brain (or cognitive) and visual function. In the Baylor prospective cohort study, pregnant women randomly received 200 mg DHA per day or placebo through at least 4 months of breastfeeding. The supplemented mothers had infants who continued to out-perform their placebo counterparts in cognitive testing at 30 months and 5 years, long after the supplementation ended.
It is recommended that all pregnant and breastfeeding women consume 200 mg of DHA daily to ensure adequate DHA deposition in brain and other tissues during critical development periods. Women can meet this recommendation by consuming two servings (4 oz each) of fish, especially fatty fish, per week. Avoid swordfish, tilefish, king mackerel and shark due to higher mercury contents in these large fish.
Breast milk which provides DHA and arachidonic acid is the preferred source of infant nutrition. Because of possible benefits and lack of adverse effects, it is recommended that infants who are not breastfed receive a formula containing both DHA and arachidonic acid.
DHA is Important for Adults, Too
DHA is especially good for heart health. DHA has been shown to lower triglycerides, heart rate and blood pressure. A DHA supplement may be helpful to maintain or improve blood lipids. A Kaiser Permanente study showed that 1000 mg a day can decrease triglyceride levels by 20%. Other research shows that DHA alone and DHA and EPA (another omega-3 fatty acid) increases HDL (good cholesterol).
Studies show that getting about 500 mg a day of DHA & EPA has the most preventative benefit for your heart. This is the amount you would get from eating about 8 oz of fatty fish a week (2 servings).
The American Heart Association recommends that all adults eat fish at least 2 times per week. Adults with heart disease should get about 1 gram daily of DHA & EPA. This can be achieved by eating fatty fish or by taking omega-3 supplements, in consultation with a physician.
Active research is in progress to determine the effects of DHA on eye health, age-related macular degeneration, prostate cancer prevention, cognitive function in the elderly, and risk for Alzheimer’s disease. In the Framingham Heart Study, people with the highest levels of DHA were 47% less likely to develop dementia than those with lower levels. An NIH-funded study is currently underway to see whether DHA alone can help people with Alzheimer’s disease stay healthier longer.
(For those who choose not to eat fish, DHA-rich fish oil supplements are a good source of DHA.)