Docosahexaenoic acid (DHA)
Docosahexaenoic acid (DHA) is an omega-3 fatty acid 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.
Omega-3 fatty acids are good for your heart, and your body needs DHA for a healthy brain. Infants need DHA, especially during the first 6 months of their lives, so their brains, eyes, and nervous systems can develop as they should. DHA is found in breast milk and is added to some infant formula.
Our bodies naturally make small amounts of DHA, but we must get the amounts we need from food or supplements. Most people in the Western world do not get enough omega-3 fatty acids in their diet.
Attention-Deficit Hyperactivity Disorder (ADHD)
Because children need omega-3 fatty acids for their brains to develop properly, researchers have examined whether fish oil might reduce ADHD symptoms. So far, results have been mixed.
Although some studies show that fish oil reduces symptoms of depression, it is not clear whether DHA by itself has the same effect. Other studies suggest EPA improves depression.
Fish oil appears to help improve outcomes for people who already have heart disease. It may also 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 2 times per week. Fatty fish include salmon, herring, lake trout, sardines and albacore tuna. People who already have heart disease may need fish oil supplements in addition to adding more fish to their diet. Ask your doctor if fish oil supplements are right for you.
DHA plays a crucial role in the growth and development of the central nervous system, as well as visual functioning in infants. Breastfed babies with healthy mothers should get enough DHA in breast milk.
Several small studies found that fish oil may help reduce symptoms and inflammation linked with rheumatoid arthritis. However, it does not stop joint damage from getting worse.
Fish oil seems to reduce the pain of menstrual cramps when taken on a regular basis (not just when menstruating).
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.
Preliminary studies suggest that fish oil may reduce the fatigue and joint pain associated with lupus.
DHA is found in cold-water, fatty fish, including salmon, tuna (bluefin tuna have up to 5 times more DHA than other types of tuna), sardines, shellfish, and herring.
Some of these fish have low levels of mercury. However, the FDA says that eating several servings of fish each week poses no risk to healthy people and offers many health benefits.
Women who are pregnant or planning to become pregnant should not eat king mackerel, shark, swordfish, and tilefish. They should also eat no more than 6 oz. per week of white albacore tuna.
To make sure you get fish oil supplements that are not contaminated with mercury, read labels carefully and check for purity, ask your doctor to help you find the best quality DHA supplement.
If the mother is healthy, breastfed babies should get enough DHA from breast milk. Infant formula may or may not have any DHA. Read labels carefully.
DHA is available as a supplement in two common forms:
- Fish oil capsules, which has both DHA and EPA (eicosapentaenoic acid), another omega-3 fatty acid
- DHA from algae, which has no EPA
How to Take It
- Babies who are breastfed should get enough DHA if their mothers are getting enough DHA in her diet. Some infant formula also has added DHA.
- Most studies have used 1,000 to 2,500 mg of DHA per day.
- In the diet: 2 to 3 servings of fatty fish per week, which equals 1,250 mg EPA and DHA per day.
- Fish oil supplements: 3,000 to 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 thinners, such as warfarin (Coumadin), clopidogrel (Plavix), or aspirin, or people who have hemophilia should check with their doctors for a safe dose.
- Pregnant women: Ask your doctor if a DHA supplement is right for you, and only use products designed for pregnant women.
- DHA supplements from algae: 200 mg per day
Some fish oil supplements also have added vitamin E to maintain freshness.
Fish oil capsules have both DHA and EPA. Supplements with 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 slightly increase the risk of bleeding. If you take blood-thinning medication, talk to your doctor before taking fish oil.
Fish oil may lower blood pressure. If you already take medication to lower blood pressure, talk to your doctor before taking fish oil.
Blood pressure medication: DHA may lower blood pressure, so it could make the effects of prescription blood pressure medication stronger. That could raise the risk of having low blood pressure.
Blood-thinners (anticoagulants and antiplatelets): EPA in fish oil supplements may increase bleeding time, so fish oil could make the effects of these drugs stronger. That does not seem to be true of DHA by itself. Blood thinners include warfarin (Coumadin), clopidogrel (Plavix), and aspirin.
Diabetes medications: Theoretically, fish oil supplements may lower blood sugar levels and could make the 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 after an organ transplant. Talk to your doctor before adding any new herbs or supplements to the medication you already take.
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