Omega-3 Fatty Acids; Types, Food Source, Daily Requirement

Omega-3 Fatty Acids; Types, Food Source, Daily Requirement

Omega-3 fatty acids are considered essential fatty acids. It is called an essential fatty acid for a reason it’s essential for your body to function. They are necessary for human health, but the body can’t make them. You have to get them through food. Omega-3 fatty acids are found in fish, such as salmon, tuna, and halibut, other seafood including algae and krill, some plants, and nut oils. Also known as polyunsaturated fatty acids (PUFAs), omega-3 fatty acids play a crucial role in brain function, as well as normal growth and development. They have also become popular because they may reduce the risk of heart disease.

Types of Omega-3 Fatty Acids

Alpha-linolenic Acid (ALA)

This plant-based omega-3 is found in green, leafy vegetables, flaxseeds, chia seeds and canola, walnut and soybean oils (although those rancid oils are not ones I generally recommend). ALA is known as a short-chain omega-3, meaning your body has to convert it into longer-chained EPA and DHA to synthesize it. This process is rather inefficient and only about one percent of the ALA you consume is converted to the long-chain version your body needs (although this percentage is slightly higher for women).

Eicosapentaenoic Acid (EPA)

EPA is a 20-carbon fatty acid found in oily fish, algae oil and krill oil. Your body is able to synthesize this molecule in its original form. This, along with DHA, are the omega-3s your body needs in high quantities to achieve the benefits they offer.

Docosahexaenoic Acid (DHA)

This 22-carbon molecule is also found in oily fish, krill oil and algae oil. Your body will convert some DHA molecules back to EPA’s in order to keep them at fairly equal levels if you consume more DHA.

Food Source of Omega-3 Fatty Acids

When possible, try to get omega-3 fatty acids from foods rather than supplements. Aim to eat fish high in DHA and EPA omega-3 fatty acids two to three times a week.

These include:

  • Anchovies
  • Bluefish
  • Herring
  • Mackerel
  • Salmon (wild has more omega-3s than farmed)
  • Sardines
  • Sturgeon
  • Lake trout
  • Tuna

Good food sources of ALA are

  • Walnuts
  • Flaxseed and flaxseed oil
  • Canola oil
  • Soybean oil

Everyone else should eat no more than 7 ounces of these fish a week. Fish like wild trout and wild salmon are safer.While foods containing omega-3 fatty acids have health benefits, some — like oils and nuts — can be high in calories. So eat them in moderation.

Food DHA and EPA Omega-3s (total), grams
Salmon, Atlantic (half fillet, grilled) 3.89
Mackerel, Pacific (1 fillet, grilled) 3.25
Sardine oil (1 tablespoon) 2.83
Salmon, Chinook (half fillet, grilled) 2.68
Cod liver oil (1 tablespoon) 2.43
Salmon, pink (half fillet, grilled) 1.60
Herring oil (1 tablespoon) 1.43
Sardines, canned in oil (approx. 3 ounces) 0.90
White tuna, canned in water (approx. 3 ounces) 0.73
Source: National Agriculture Library, U.S. Dept. of Agriculture

For a more nutritious diet and potentially better eye health, try these simple changes: chart

  1. Replace cooking oils that are high in omega-6 fatty acids with olive oil, which has significantly lower levels of omega-6 fatty acids.
  2. Eat plenty of fish, fruits and vegetables.
  3. Avoid hydrogenated oils (found in many snack foods) and margarine.
  4. Avoid fried foods and foods containing trans fats.
  5. Limit your consumption of red meat.

Daily Requirement in Human Body

The American Heart Association (AHA) recommends that healthy people who do not have heart disease eat some type of fatty fish at least twice a week. And they should include oils and foods rich in alpha-linolenic acid in their diet. Flaxseed, canola and soybean oils, and walnuts contain this acid.Food is the best way to get omega-3 fatty acids because food contains other healthy substances. For example, fish contains arginine, glutamine, and selenium. All of these may benefit the heart and blood vessels. Flaxseed and walnuts have substances that help lower total cholesterol.

The AHA offers this rundown on the omega-3 content of some fish, per 3-ounce serving:

  • Canned light tuna: 0.17 to 0.24 grams

  • Shrimp: 0.29 grams

  • Pollock: 0.45 grams

  • Fresh or frozen salmon: 1.1 to 1.9 grams

  • Cod: 0.15 to 0.24 grams

  • Catfish: 0.22 to 0.3 grams

  • Clams: 0.25 grams

  • Flounder or sole: 0.48 grams

  • Crabs: 0.27 to 0.4 grams

  • Scallops: 0.18 to 0.34 grams

Dosages of Omega-3 Fatty Acids

There is no Recommended Dietary Allowance (RDA) for omega-3 fatty acids in general or for the individual omega-3s, i.e., EPA or DHA.

Most research studies have found that participants benefited from 500 to 1,000 milligrams of total omega-3s per day, so this is a basic dosage rule of thumb.

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Experts generally recommend 500 to 1,000 mg of total omega-3s per day to maintain health and avoid deficiency, but therapeutic doses (to raise low levels or treat a health condition) up to 3 grams are generally considered safe.

However, some studies use much more than this.

Renowned neurology researcher Dr. Datis Kharrazian, author of Why Isn’t My Brain Working?, recommends 5 grams of fish oil daily for patients with issues like depression, bipolar disorder, or memory loss, with the emphasis on DHA rather than EPA.Note that when considering dosages, you should consider the total amounts of EPA and DHA, not the total amount of fish oil or krill oil. You can see if you are getting adequate omega-3s with this omega-3 quiz created by, a not-for-profit educational

Side Effects of Omega-3 Fatty Acids

Less common Incidence not known
Bad, unusual, or unpleasant (after) taste Diarrhea
Belching Difficulty having a bowel movement (stool)
anorexia Loss of appetite
Change in taste Nausea or vomiting
Excess air or gas in the stomach Passing of gas
Heartburn Stomach fullness
Stomach discomfort, upset, or pain

Like any other essential nutrient, an imbalance of Omega-3 fatty acid levels in the body will produce certain side effects. Most of these side effects stem from the consumption of mainly synthetic forms of Omega 3 fatty acids, or the lack of consumption of sufficient quantities of these essential nutrients. Stomach upsets and nausea are the most commonly reported side effects of Omega3 capsules. Fish oil produces most of these and other side effects.

Possible Drug Interactions of Omega-3 Fatty Acids

If you are currently being treated with any of the following medications, you should not use omega-3 fatty acid supplements, including EPA, DHA, and ALA, without first talking to your health care provider.

Blood-thinning medicationsOmega-3 fatty acids may increase the effects of blood-thinning medications, including aspirin, warfarin (Coumadin), and clopedigrel (Plavix). Taking aspirin and omega-3 fatty acids may be helpful in some circumstances (such as in heart disease), but you should only take them together under the supervision of a provider.

Diabetes medicationsTaking omega-3 fatty acid supplements may increase fasting blood sugar levels. Talk to your doctor if you are taking medications to lower blood sugar, such as glipizide (Glucotrol and Glucotrol XL), glyburide (Micronase or Diabeta), glucophage (Metformin), or insulin. Your doctor may need to increase your medication dose. These drugs include:

  • Glipizide (Glucotrol and Glucotrol XL)
  • Glyburide (Micronase or Diabeta)
  • Metformin (Glucophage)
  • Insulin

CyclosporineCyclosporine is a medication given to people with organ transplants. Taking omega-3 fatty acids during cyclosporine (Sandimmune) therapy may reduce toxic side effects, such as high blood pressure and kidney damage, associated with this medication.

Etretinate and topical steroids Adding omega-3 fatty acids (specifically EPA) to the drug therapy etretinate (Tegison) and topical corticosteroids may improve symptoms of psoriasis.

Cholesterol-lowering medicationsFollowing dietary guidelines, including increasing the amount of omega-3 fatty acids in your diet and reducing the omega-6 to omega-3 ratio, may help a group of cholesterol-lowering medications called statins work more effectively. These medications include:

Nonsteroidal anti-inflammatory drugs (NSAIDs)In an animal study, treatment with omega-3 fatty acids reduced the risk of ulcers from NSAIDs. NSAIDs include ibuprofen (Motrin or Advil) and naproxen (Aleve or Naprosyn). More research is needed to see whether omega-3 fatty acids would have the same effects in people.

Health Benefit of omega -3

Omega-3s Can Improve Risk Factors For Heart Disease

Heart attacks and strokes are the world’s leading causes of death Decades ago, researchers observed that fish-eating communities had very low rates of these diseases. This was later found to be partially due to omega-3 consumption .Since then, omega-3 fatty acids have been shown to have numerous benefits for heart health .

These include:

  • Triglycerides – Omega-3s can cause a major reduction in triglycerides, usually in the range of 15–30%
  • Blood pressure – Omega-3s can reduce blood pressure levels in people with high blood pressure
  • HDL-cholesterol – Omega-3s can raise HDL (the “good”) cholesterol levels
  • Blood clots – Omega-3s can keep blood platelets from clumping together. This helps prevent the formation of harmful blood clots .
  • Plaque –By keeping the arteries smooth and free from damage, omega-3s help prevent the plaque that can restrict and harden the arteries .
  • Inflammation- Omega-3s reduce the production of some substances released during the inflammatory response .

For some people, omega-3s can also lower LDL (the “bad”) cholesterol. However, the evidence is mixed and some studies actually find increases in LDL.Interestingly, despite all these beneficial effects on heart disease risk factors, there is no convincing evidence that omega-3 supplements can prevent heart attacks or strokes. Many studies find no benefit.

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Blood fat (triglycerides)

Fish oil supplements can lower elevated triglyceride levels. Having high levels of this blood fat puts you at risk for heart disease.

Rheumatoid arthritis

Fish oil supplements (EPA+DHA) can curb stiffness and joint pain. Omega-3 supplements also seem to boost the effectiveness of anti-inflammatory drugs.


Some researchers have found that cultures that eat foods with high levels of omega-3s have lower levels of depression. Fish oil also seems to boost the effects of antidepressants and may help the depressive symptoms of bipolar disorder.

Baby development

DHA appears to be important for visual and neurological development in infants.


A diet high in omega-3s lowers inflammation, a key component in asthma. But more studies are needed to show if fish oil supplements improve lung function or cut the amount of medication a person needs to control the condition.

Alzheimer’s disease and dementia

Some research suggests that omega-3s may help protect against Alzheimer’s disease and dementia, and have a positive effect on gradual memory loss linked to aging. But that’s not certain yet.

Macular degeneration

A questionnaire given to more than 3,000 people over the age of 49 found that those who ate more fish were less likely to have macular degeneration, a serious age-related eye condition that can progress to blindness, than those who ate less fish. Similarly, a clinical study comparing 350 people with macular degeneration to 500 without the eye disease found that those with a healthy dietary balance of omega-3 and omega-6 fatty acids, as well as more fish in their diets, were less likely to have macular degeneration.

Menstrual pain

In one study of 42 women, participants had less menstrual pain when they took fish oil supplements than when they took placebo.

Colon cancer

Eating foods rich in omega-3 fatty acids seems to reduce the risk of colorectal cancer. For example, Eskimos, who tend to have a high fat diet, but eat significant amounts of fish rich in omega-3 fatty acids, have a low rate of colorectal cancer. Animal studies and laboratory studies have found that omega-3 fatty acids prevent worsening of colon cancer.

Breast cancer

Although not all experts agree, women who eat foods rich in omega-3 fatty acids over many years may be less likely to develop breast cancer. More research is needed to understand the effect that omega-3 fatty acids may have on the prevention of breast cancer.

Prostate cancer

Population-based studies of groups of men suggest that a low-fat diet including omega-3 fatty acids (from fish or fish oil) may help prevent the development of prostate cancer.

Bipolar disorder

In a clinical study of 30 people with bipolar disorder, those who took fish oil in addition to standard prescription treatments for bipolar disorder for 4 months experienced fewer mood swings and relapses than those who received placebo. But another 4-month long clinical study treating people with bipolar depression and rapid cycling bipolar disorder did not show that EPA helped reduce symptoms.


Preliminary clinical evidence suggests that people with schizophrenia take omega-3 fatty acids, they experience an improvement in symptoms. However, more recent research found that EPA supplements were no better than placebo in improving symptoms of this condition.

Attention deficit/hyperactivity disorder (ADHD)

Children with ADHD may have low levels of certain essential fatty acids (including EPA and DHA). In a clinical study of nearly 100 boys, those with lower levels of omega-3 fatty acids had more learning and behavioral problems (such as temper tantrums and sleep disturbances) than boys with normal omega-3 fatty acid levels.However, studies examining whether omega-3 fatty acids help improve symptoms of ADHD have produced mixed results. A few studies show that omega-3 fatty acids help improve behavioral symptoms.

Cognitive decline

Several studies show that reduced intake of omega-3 fatty acids is associated with increased risk of age-related cognitive decline or dementia, including Alzheimer disease. Scientists believe the omega-3 fatty acid DHA is protective against Alzheimer disease and dementia.

Skin disorders

In one clinical study, 13 people with sun sensitivity known as photo dermatitis showed less sensitivity to UV rays after taking fish oil supplements. However, topical sunscreens are much better at protecting the skin from damaging effects of the sun than omega-3 fatty acids. In another study of 40 people with psoriasis, those who took EPA with their prescription medications did better than those treated with the medications alone. However, a larger study of people with psoriasis found no benefit from fish oil.

Inflammatory bowel disease (IBD)

Results are mixed as to whether omega-3 fatty acids can help reduce symptoms of Crohn disease and ulcerative colitis, two types of IBD. Some studies suggest that omega-3 fatty acids may help when added to medication, such as sulfasalazine (a standard medication for IBD). Others show no effect. More studies are needed. Fish oil supplements can cause side effects that are similar to symptoms of IBD (such as flatulence, belching, bloating, and diarrhea).

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Systemic lupus erythematosus (SLE)

Several small studies suggest that EPA and fish oil may help reduce symptoms of lupus, an autoimmune condition characterized by fatigue and joint pain. However, two small studies found that fish oil had no effect on lupus nephritis (kidney disease caused by lupus, a frequent complication of the disease).


Some studies suggest that omega-3 fatty acids may help increase levels of calcium in the body and improve bone strength, although not all results were positive. Some studies also suggest that people who do not get enough of some essential fatty acids (particularly EPA and gamma-linolenic acid (GLA), an omega-6 fatty acid) are more likely to have bone loss than those with normal levels of these fatty acids. In a study of women over 65 with osteoporosis, those who took EPA and GLA supplements had less bone loss over 3 years than those who took placebo. Many of these women also experienced an increase in bone density.

Alleviate Menstrual Pain

Menstrual pain occurs in the lower abdomen and pelvis, and often radiates to the lower back and thighs.It can result in significant negative effects on a person’s quality of life.However, studies have repeatedly shown that women who consume the most omega-3s have milder menstrual pain .One study even found that an omega-3 supplement was more effective than ibuprofen in treating severe pain during menstruation

Improve Sleep

Good sleep is one of the foundations of optimal health.Studies show that sleep deprivation is linked to many diseases, including obesity, diabetes and depression .Low levels of omega-3 fatty acids are associated with sleep problems in children and obstructive sleep apnea in adults Low levels of DHA have also been linked to lower levels of the hormone melatonin, which helps you fall asleep .Studies in both children and adults have shown that supplementing with omega-3 increases the length and quality of sleep

Good For Your Skin

DHA is a structural component of the skin. It is responsible for the health of cell membranes, which make up a large part of skin.A healthy cell membrane results in soft, moist, supple and wrinkle-free skin.EPA also benefits the skin in several ways, including

  • Managing oil production in skin.
  • Managing hydration of the skin.
  • Preventing hyperkeratinization of hair follicles (the little red bumps often seen on upper arms).
  • Preventing premature ageing of the skin.
  • Preventing acne.

Omega-3s can also protect your skin from sun damage. EPA helps block the release of substances that eat away at the collagen in your skin after sun exposure .

DO NOT take more than 3 grams daily of omega-3 fatty acids from capsules without the supervision of a health care provider, due to an increased risk of bleeding.
  • For healthy adults with no history of heart disease: The AHA recommends eating fish at least 2 times per week.
  • For adults with coronary heart disease: The AHA recommends an omega-3 fatty acid supplement (as fish oils), 1 gram daily of EPA and DHA. It may take 2 to 3 weeks before you experience benefits from fish oil supplements. You should take supplements under the direction of a physician.
  • For adults with high cholesterol levels: The AHA recommends an omega-3 fatty acid supplement (as fish oils), 2 to 4 grams daily of EPA and DHA. It may take 2 to 3 weeks to experience benefits from fish oil supplements. Supplements should be taken under the direction of a physician.



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