The three main omega-3 fatty acids are alpha-linolenic acid ALA , eicosapentaenoic acid EPA , and docosahexaenoic acid DHA. ALA is found mainly in plant oils such as flaxseed, soybean , and canola oils. DHA and EPA are found in fish and other seafood. Your body can convert some ALA into EPA and then to DHA, but only in very small amounts.

Therefore, getting EPA and DHA from foods and dietary supplements if you take them is the only practical way to increase levels of these omega-3 fatty acids in your body.

Omega-3s are important components of the membranes that surround each cell in your body. DHA levels are especially high in retina eye , brain, and sperm cells. Omega-3s also provide calories to give your body energy and have many functions in your heart, blood vessels , lungs , immune system , and endocrine system the network of hormone -producing glands.

Experts have not established recommended amounts for omega-3 fatty acids, except for ALA. Average daily recommended amounts for ALA are listed below in grams g.

The amount you need depends on your age and sex. Omega-3s are found naturally in some foods and are added to some fortified foods. You can get adequate amounts of omega-3s by eating a variety of foods, including the following:.

Omega-3 dietary supplements include fish oil, krill oil, cod liver oil, and algal oil a vegetarian source that comes from algae. They provide a wide range of doses and forms of omega-3s. Most people in the United States get enough ALA from the foods they eat.

They also get small amounts of EPA and DHA. Recommended amounts of EPA and DHA have not been established.

A deficiency of omega-3s can cause rough, scaly skin and a red, swollen, itchy rash. Omega-3 deficiency is very rare in the United States.

Scientists are studying omega-3s to understand how they affect health. People who eat fish and other seafood have a lower risk of several chronic diseases. However, it is not clear whether these health benefits come from simply eating these foods or from the omega-3s in these foods.

Here are some examples of what the research has shown. Many studies show that eating fatty fish and other types of seafood as part of a healthy eating pattern helps keep your heart healthy and helps protect you from some heart problems.

Getting more EPA and DHA from foods or dietary supplements lowers triglyceride levels, for example. They also provide the starting point for making hormones that regulate blood clotting, contraction and relaxation of artery walls, and inflammation.

In addition, they can bind to receptors in cells that regulate genetic function. Due to these effects, omega-3 fats can help prevent heart disease and stroke, may help control lupus, eczema, and rheumatoid arthritis, and may play protective roles in cancer and other conditions.

The strongest evidence for a beneficial effect of omega-3 fats has to do with heart disease. These fats appear to help the heart beat at a steady clip and not veer into a dangerous or potentially fatal erratic rhythm. Omega-3 fats also lower blood pressure and heart rate, and improve blood vessel function.

At higher doses, they lower triglycerides and may ease inflammation, which plays a role in the development of atherosclerosis. Given the wide-ranging importance of marine omega-3 fatty acids, it is important to eat fish or other seafood times a week, particularly fatty dark meat fish that is richer in EPA and DHA.

From the third trimester until the second year of life, a developing child needs a steady supply of DHA to form the brain and other parts of the nervous system as DHA is the most abundant fatty acid in the brain.

Many women shy away from eating fish because of concerns that mercury and other possible contaminants might harm their babies, [4] yet the evidence for harm from lack of omega-3 fats is far more consistent, and a balance of benefit vs.

risk is easily obtained by limiting intake of the types of fish higher in mercury. To learn more about the controversy over contaminants in fatty fish, read Fish: Friend or Foe.

Researchers are also looking at the effects of marine and plant omega-3 fats on prostate cancer. Results from the Health Professionals Follow-up Study and others show that men whose diets are rich in EPA and DHA mainly from fish and seafood are less likely to develop advanced prostate cancer than those with low intakes of EPA and DHA.

However, this effect is inconsistent. In the Prostate, Lung, Colorectal, and Ovarian PLCO Cancer Screening Trial, for example, there was no link between ALA intake and early, late, or advanced prostate cancer.

ALA is an important source of omega-3 fats for those who have a fish allergy or who eat a vegan diet. Fish oil pills contain both EPA and DHA. Research strongly supports that eating a diet with fatty fish weekly provides protection from cardiovascular disease.

However, many large clinical trials have not shown that taking omega-3 supplements provide the same protection. Another reason could be the increased use of highly effective statin medications, which might outshine any modest benefit provided from omega-3 supplements.

A scientific advisory from the American Heart Association reviewed the results of large randomized controlled trials studying the effects of marine-based omega-3 supplements e. This could be because more people were consuming fatty fish rich in omega-3 during the recent trials, so that taking supplements did not offer more benefit.

Another reason is that the use of statins, beta-blockers, and other heart medications were used in more patients in later trials, so that any benefit of taking omega-3 supplements was decreased.

However, there was not enough evidence to recommend supplements for the prevention of cardiovascular diseases. The Food and Drug Administration specifies that the labels of dietary supplements should not recommend a daily intake of EPA and DHA higher than mg due to lack of evidence.

For people with heart disease, the American Heart Association AHA recommends mg daily of EPA and DHA, preferably from fish, but supplements can be considered in consultation with a physician. An alternative to fish oil is algal oil, derived from algae, the omegarich ocean plants eaten by small marine life that is consumed by larger fatty fish.

Algal oil contains mostly DHA, and although costlier than fish oil supplements, it is vegan and more sustainably produced without reliance on marine fishing.

A review of randomized controlled trials found that algal oil supplementation may help to reduce triglycerides in people without established heart disease. Omega-3 supplements can act as a mild blood thinner and may increase the risk of bleeding.

Inform your doctor if you begin using these supplements as they may also interact with some medications, especially blood thinners. Prior to , cattle were typically allowed to pasture and consume a diet of mostly grass. As demands for production increased, cattle were instead fed high-calorie grains made from soy or corn that also created a desirable marbling of the meat from the higher fat content.

Today, most cows in the U. are still generally fed a grain-based diet; to further speed growth they may be given growth hormone and are restricted in movement. One might imagine that cows fed primarily grass would be exposed to a more natural habitat of grazing freely and consuming native vegetation, high in nutrients and omega-3 fats.

They may simply be fed grass or vegetation in a confined space. Regardless if cattle are grain or grass-fed, the majority of fat in the beef is saturated, and the amount of total saturated fat is similar regardless of feeding type. The ratio of saturated to unsaturated fat is also similar for grain or grass-fed cattle, but generally grass-fed beef is leaner with less total fat.

But a recent study has raised some questions. The STRENGTH trial , published in JAMA , looked at a different formulation of omega-3 fish oil — a combination of EPA and DHA — to see if it would also reduce cardiovascular risk.

The trial was terminated early due to an interim analysis revealing no difference between the two treatment groups. One possibility is that the different results are due to the different drugs studied.

REDUCE-IT studied a purified formulation of high-dose EPA, which resulted in higher EPA levels. This was similar to the results of another trial , which also found that pure EPA reduced the risk of cardiac events.

The STRENGTH trial tested a combination of EPA and DHA. No large study has ever evaluated the effects on cardiovascular outcomes of purified DHA alone, leaving us to wonder whether DHA might counteract the benefits of EPA. Back to my patients who want to know if they should be taking an omega-3 supplement.

Eat a heart-healthy diet, get regular exercise, and pursue other lifestyle changes that have proven benefits for cardiovascular health. In the meantime, my colleagues and I wait for more definitive data on the utility of omega-3 fish oil, and who might benefit the most.

Alyson Kelley-Hedgepeth, MD , Contributor. As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

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They provide a wide range of doses and forms of omega-3s. Most people in the United States get enough ALA from the foods they eat. They also get small amounts of EPA and DHA. Recommended amounts of EPA and DHA have not been established. A deficiency of omega-3s can cause rough, scaly skin and a red, swollen, itchy rash.

Omega-3 deficiency is very rare in the United States. Scientists are studying omega-3s to understand how they affect health. People who eat fish and other seafood have a lower risk of several chronic diseases. However, it is not clear whether these health benefits come from simply eating these foods or from the omega-3s in these foods.

Here are some examples of what the research has shown. Many studies show that eating fatty fish and other types of seafood as part of a healthy eating pattern helps keep your heart healthy and helps protect you from some heart problems.

Getting more EPA and DHA from foods or dietary supplements lowers triglyceride levels, for example. The American Heart Association AHA recommends eating one to two servings of seafood per week to reduce your risk of some heart problems, especially if you consume the seafood in place of less healthy foods.

For people with heart disease, the AHA recommends consuming about 1 g per day EPA plus DHA, preferably from oily fish, but supplements are an option under the guidance of a health care provider.

The AHA does not recommend omega-3 supplements for people who do not have a high risk of cardiovascular disease. However, it is important to choose fish that are higher in EPA and DHA and lower in mercury. Examples are salmon, herring, sardines, and trout. Breast milk contains DHA. Most commercial infant formulas also contain DHA.

Some studies suggest that people who get more omega-3s from foods and dietary supplements may have a lower risk of breast cancer and perhaps colorectal cancer. However, a large clinical trial found that omega-3 supplements did not reduce the overall risk of cancer or the risk of breast, prostate, or colorectal cancers.

Other clinical trials in progress will help clarify whether omega-3s affect cancer risk. Some—but not all—research shows that people who consume more omega-3s from food such as fish may have a lower risk of developing Alzheimer's disease, dementia , and other problems with cognitive function.

More study of the effects of omega-3s on the brain is needed. Age-related macular degeneration AMD is a major cause of vision loss among older adults.

Studies suggest that people who get higher amounts of omega-3s from the foods they eat may have a lower risk of developing AMD. Mayo Clinic offers appointments in Arizona, Florida and Minnesota and at Mayo Clinic Health System locations.

The omega-3 fatty acids in fish are good for the heart. Find out why the heart-healthy benefits of eating fish usually outweigh any risks.

If you're worried about your heart health, eating at least two servings of fish a week could reduce your risk of heart disease. The American Heart Association recommends eating fish rich in unsaturated fats at least twice a week.

All fish are a good source of protein, vitamins and minerals. But fatty fish contain omega-3 fatty acids. Omega-3s and other nutrients in fish may improve heart health. They also may lower the risk of dying of heart disease. Some people may worry about mercury or other contaminants in fish.

But the benefits of eating fish as part of a healthy diet usually outweigh the possible risks of exposure to contaminants.

Learn how to balance these concerns with adding a healthy amount of fish to your diet. Omega-3 fatty acids are a type of unsaturated fatty acid. They may lower inflammation in the body. Inflammation in the body can hurt blood vessels.

Blood vessel damage may lead to heart disease and stroke. Try to eat at least two servings a week of fish, especially fish that's rich in omega-3 fatty acids. Doing so appears to reduce the risk of heart disease, particularly sudden cardiac death. Many types of seafood contain small amounts of omega-3 fatty acids.

Fatty fish contain the most omega-3 fatty acids and seem to benefit the heart the most. The U. Food and Drug Administration FDA recommends fish as part of a healthy diet for most people. But people in some groups should limit how much fish they eat. Most adults should eat two servings of omegarich fish a week.

A serving size is 4 ounces grams or about the size of a deck of cards. If you are pregnant, are planning to get pregnant or are breastfeeding, do not eat fish that's typically high in mercury. This includes shark, swordfish, king mackerel and tilefish. Limit the amount of other fish you eat to:.

You can still get heart-healthy benefits from a variety of seafood and fish that are typically low in mercury, such as salmon and shrimp. Young children also should not eat fish that contain potentially high levels of mercury. Kids should eat fish from choices lower in mercury once or twice a week.

The serving size of fish for kids younger than age 2 is 1 ounce 28 grams and increases with age. To get the most health benefits from eating fish, pay attention to how it's cooked.

For example, grilling, broiling or baking fish is a healthier option than is deep-frying. If you eat a lot of fish containing mercury, the toxin can build up in your body. It's unlikely that mercury would cause any health concerns for most adults.

But mercury is very harmful to the development of the brain and nervous system of unborn babies and young children. For most adults, the benefits of omega-3 fatty acids outweigh the risk of getting too much mercury or other toxins.

The main toxins in fish are mercury, dioxin and polychlorinated biphenyls, also called PCBs. The amounts of toxins depend on the type of fish and where it's caught.

A little bit of mercury occurs naturally in the environment. But pollution from factories and other industries can produce mercury that collects in lakes, rivers and oceans.

That pollution can end up in the food that fish eat. When fish eat this food, mercury builds up in their bodies. Large fish that are higher in the food chain eat smaller fish. So large fish get even more mercury.

The longer a fish lives and eats, the larger it grows and the more mercury it can collect. Fish that may contain higher levels of mercury include:.

Some studies say high levels of omega-3 fatty acids in the blood increase the risk of prostate cancer. But other studies say high levels of omega-3s might prevent prostate cancer.

None of these studies was definite. More research is needed. Talk with a health care professional about what this potential risk might mean to you. Some researchers also are concerned about eating fish grown on farms as opposed to fish caught in the wild.

Antibiotics, pesticides and other chemicals may be used in raising farmed fish. But the FDA says the levels of contaminants in farmed fish don't seem to be bad for health. Some people use omega-3 supplements for dry eyes. In , however, a year-long study involving people with moderate-to-severe dry eyes found no evidence to suggest that taking supplements was more helpful than taking a placebo for this purpose.

Epilepsy is a neurological condition. Some studies have suggested that taking omega-3 supplements may help reduce the number of seizures a person experiences. However, a review did not find conclusive evidence to suggest that this can help prevent symptoms.

Omega-3 consumption may help boost fetal development, especially of the brain and eyes. This is one that reason experts recommend consuming oily fish during pregnancy. However, it is important to avoid eating fish with high levels of mercury, such as shark and king mackerel, during this time.

In , scientists concluded that consuming omega-3 during pregnancy may improve memory function in school-age children. In most cases, the best way to consume nutrients is through food, unless a doctor recommends taking supplements.

Animal-based sources of omega-3 include:. However, omega-3 supplements are unlikely to cause any severe adverse effects, according to the National Center for Complementary and Integrative Health.

That said, people should check with their doctor before using them, as there may be some risks. For example:. The Food and Drug Administration FDA do not regulate the quality or purity of supplements. It is, therefore, essential to buy them from a reputable source.

Learn more about the possible side effects of taking fish oil here. Consuming more fish oil and omega-3 may bring some health benefits, but eating a diet that offers a variety of nutrients is likely to be healthful.

Anyone who is considering taking supplements should first check with a healthcare provider to ensure that it is safe. Shop here for fish oil supplements. Omega-3 fatty acids are present in foods such as fish. Their potential benefits include reducing inflammation and heart disease risk.

Adversely, omega-. Fish oil supplements contain healthful omega-3 fatty acids. These dietary fats are available in fresh fish, as well, but too many may lead to unwanted…. The amount of omega-3 a person needs each day depends on their age and sex.

People with certain health conditions, including heart disease, depression,. What are micronutrients? Read on to learn more about these essential vitamins and minerals, the role they play in supporting health, as well as….

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