Docosahexaenoic Acid
OTHER NAME(S): DHA, docosahexaenoic acid
Overview
Docosahexaenoic acid (DHA) is a type of omega-3 fatty acid that is found in fish, some other foods, and over-the-counter supplements. It is used for many reasons, although its benefits are not well defined. Common side effects include heartburn, nausea, upset stomach, and diarrhea. Before taking DHA, tell your health care provider about all of your health conditions, including any food allergies, and any medicines or supplements you may be using.
Uses
What is docosahexaenoic acid (DHA) used for?
DHA is used for many reasons. However, its benefits are not well defined. Some common reasons for using DHA include the following.
- For certain eye problems, including dry eyes and age-related macular degeneration (AMD)
- For heart health
- For brain development in infants
- To improve memory and thinking skills
DHA may also be used for other conditions as determined by your health care provider.
Note: The FDA has not reviewed DHA for safety and effectiveness. Learn more about dietary supplements here.
DHA is a type of omega-3 fatty acid that is found in fish oil. Learn more about fish oil supplements here. Learn more about fish oil prescription medicines here.
DHA is also found in other oils, including krill oil, cod liver oil, and algal oil. Many supplements that contain DHA are made from these oils and may also contain another omega-3 fatty acid called eicosapentaenoic acid (EPA).
How does DHA work (mechanism of action)?
DHA is a type of omega-3 fatty acid. These fatty acids give you calories for energy and help with many functions in your brain, heart, blood vessels, lungs, eyes, and immune system. They also play an important role in the healthy development of the brain and eyes, starting in the womb and continuing throughout early childhood.
In the U.S., most people get enough DHA from their diet. DHA is found in fish, especially fatty fish, such as cod, salmon, tuna, and mackerel. It is also added to some fortified foods, including eggs, yogurt, juices, milk, soy drinks, and baby formulas. For most adults, there is no recommended daily intake for DHA. However, adults with heart disease or those who are pregnant or breastfeeding should try to get a certain amount of DHA in their diets (see the Sources section for more details). This amount of DHA can come from eating two to three servings of low-mercury fish each week.
DHA supplements are sometimes marketed for eye problems and memory issues. But DHA does not seem to be helpful for improving memory and thinking skills in people with dementia or for improving eyesight in people with a condition called age-related macular degeneration (AMD). The benefits of DHA for other uses are not well defined.
DHA is also a popular supplement for heart health, but only when combined with another omega-3 fatty acid called eicosapentaenoic acid (EPA). DHA and EPA are both found in fish oil, and research for heart health has used very high doses of these two fatty acids together. The benefits of taking DHA alone for heart health are not well defined.
How should I store DHA?
You should store DHA according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.
Side Effects
What are the most common side effects of DHA?
The most common side effects of DHA are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.
- Bad taste in your mouth or bad breath
- Heartburn
- Nausea, upset stomach, or diarrhea
- Sweat that smells bad
There may be other side effects of DHA that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of DHA?
While less common, the most serious side effects of DHA are described below, along with what to do if they happen.
Severe Allergic Reactions. DHA may cause allergic reactions, which can be serious. Stop taking DHA and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching or skin rash
- Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Precautions
Who should not use DHA?
Allergies to Ingredients. People who are allergic to any of the following should not take DHA.
- DHA
- Docosahexaenoic acid
- Any of the ingredients in the specific product
Your pharmacist can tell you all of the ingredients in the specific DHA products they stock.
What should I know about DHA before using it?
DHA is a dietary supplement. It cannot be marketed to treat or cure a disease.
Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.
Keep DHA out of the reach of children.
DHA supplements are often made from the oils of fish, krill, or algae. Krill are a type of crustacean (similar to shrimp) that are eaten by fish, whales, penguins, and other sea creatures. Read the product label closely to confirm the source of DHA. Supplements made from algae are considered vegetarian.
If you are taking liquid DHA, use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist what measuring device to use.
The FDA has not tested DHA products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.
What should I tell my health care provider before using DHA?
Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if DHA is right for you.
In particular, make sure that you discuss any of the following.
Food Allergy.Supplements that contain DHA may be made from fish or krill. You may be at risk of an allergic reaction to these supplements if you are allergic to fish or shellfish, such as shrimp, crab, lobster, oysters, or scallops. Some DHA supplements are made from algae, which may be safe for people with fish or shellfish allergies. Before taking DHA, tell your health care provider if you are allergic or think that you may be allergic to either fish or shellfish.
Pregnancy. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take DHA while you are pregnant or trying to get pregnant.
Breastfeeding. DHA passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.
Interactions
Does DHA interact with foods or drinks?
There are no known interactions between DHA and foods or drinks.
It is unknown if drinking alcohol will affect DHA.
Does DHA interact with medicines (drug interactions)?
Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
The interactions between DHA and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with DHA is incomplete. Always check with your health care provider before taking DHA with any medicines.
Dosing
What should I do if I accidentally use too much DHA?
If you or someone else has used too much DHA, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
DHA supplements come in many doses and forms and often contain other ingredients. Read the product label closely, and speak with a health care provider about how to take DHA safely. Do not take double or extra doses, even if you miss a dose.
References
- American Heart Association: “Are You Getting Enough Omega-3 Fatty Acids?”
- American Pregnancy Association: “Are Omega-3 Supplements Good for My Baby?”
- National Center for Complementary and Integrative Health: “Omega-3 Supplements: What You Need To Know.”
- National Institutes of Health, Office of Dietary Supplements: “Omega-3 Fatty Acids, Fact Sheet for Consumers,” “Omega-3 Fatty Acids, Fact Sheet for Health Professionals.”