Your Ultimate Guide to Omega-3, -6 and -9 Fish Oils

Get the healthy benefits from the omega fatty acids from food or from fish oil supplements.
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Omega-3, omega-6 and omega-9 fatty acids are essential components for keeping your body healthy. Each fat is linked to lower rates of chronic degenerative diseases.


While you can get these fats from foods, some diets may be lower in them than others, which is where supplements can help.

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While all of the omega fats are important, fish oil supplements only contain omega-3 fats. That's because most American diets are high in omega-6s and your body can make omega-9s on its own, so you don't need to supplement it.


Taking fish oil with anticoagulant medications might increase your risk of bleeding, per the Australian Department of Health. Talk to your doctor before taking fish oil supplements.

What Is Omega-3?

Omega-3 fatty acids are essential fatty acids, meaning they cannot be made or stored in the body, so you must get enough from food or supplements.

You'll find omega-3s in both marine and plant-based foods. There are several kinds of omega-3 fatty acids. The three most common are:

  • Eicosapentaenoic acid​ (EPA): The main function of EPA is to reduce inflammation and support your circulatory and heart health as well as blood pressure, per Mount Sinai. It's also linked to better brain health. EPA is found in fish and seafood and is usually a component of fish oil supplements.
  • Docosahexaenoic acid​ (DHA): The retina, brain and sperm cells have high concentrations of DHA, per the NIH. As a polyunsaturated fat, DHA can support your mood, mental performance, cognitive function, memory and learning ability. DHA is found in fish and seafood and is usually a component of fish oil supps.
  • Alpha-linolenic acid​ (ALA): ALA is an essential omega-3 fat found primarily in fatty plant sources such as flax and chia seeds. Your body uses ALA for energy. It can be converted into EPA and DHA, but only in limited amounts, according to the NIH.


Benefits of Omega-3s

Omega-3 touts plenty of health benefits and is important for the functions of your heart, brain, lungs, blood vessels and immune system, per the National Institutes of Health (NIH).

Supplementing with omega-3s or eating more fatty fish is linked to lower triglycerides and larger HDL particles, which are better at removing unhealthy cholesterol and potentially preventing plaque buildup and heart disease, according to a large February 2020 study in ​JAHA​.



When it comes to fish oil's skin benefits, omega-3s also help repair damaged cell membranes, making the skin more resilient to internal and external threats. Fatty acids are emollients, natural moisturizers that revitalize dry skin. Fish oil is rich in polyunsaturated fats, helping restore fats lost in the skin and helping with dryness.

It can also protect against the damaging effects of sunlight, per the Linus Pauling Institute. Sunscreen is still the best defense but when used in conjunction with omega-3, makes a powerful combatant. What's more, getting enough omega-3s in your diet is linked to a youthful skin appearance.


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Omega-3s and Weight Loss

Some people look to omega-3s for weight loss. Studies that link weight loss to omega-3 fatty acids have focused chiefly on fish oil.

A May 2005 study in ​The American Journal of Nutrition​ suggests that combining exercise with fish oil may help amplify weight loss: Participants who took fish oil and exercised lost more than those who just took fish oil or exercised. But another July 2013 ​Appetite​ study found that fish oil may increase appetite.


So, the jury is still out on whether omega-3s can help you lose weight.

Sources of Omega-3

According to the University of Rochester, some of the best fish sources of omega-3, with the quantity per 3-ounce serving, are:

  • Salmon: 1.1 to 1.9 g
  • Flounder or sole: 0.48 g
  • Pollock: 0.45 g
  • Scallops: 0.18 to 0.34 g
  • Shrimp: 0.29 g
  • Crab: 0.27 to 0.4 g
  • Clams: 0.25 g
  • Canned tuna: 0.17 to 0.24 g
  • Catfish: 0.22 to 0.3 g
  • Cod: 0.15 to 0.24 g


The USDA recommends replacing meat with fish to get more omega-3s. The American Heart Association recommends you eat at least two 3.5-ounce servings of fish per week. Getting your omega-3s from food is preferable but, if you can't eat enough omega-3-rich foods, you may want to consider fish oil supplements.


Plant sources, including the following, can also help supply your omega-3 requirements and are great for vegetarians and vegans, per Penn Medicine:


  • Flaxseeds
  • Walnuts
  • Chia seeds
  • Canola oil
  • Soy oil
  • Soybeans
  • Tofu

Plants contain the ALA type of omega-3, which doesn't efficiently convert into the active forms EPA and DHA. Fortified foods can also be a good source of omega-3s.

Omega-3 fats are important for your heart, brain, skin and immune system. They are essential fats, which means you need to get them from your diet. The best sources of omega-3s are fatty fish (like salmon and herring) but you could also get them from plant-based foods such as flax and chia seeds, walnuts and tofu.

What Is Omega-6?

Omega-6 is also an essential polyunsaturated fatty acid, primarily used to produce energy in your body.

While our bodies need omega-6s, some seem to trigger inflammation, but others seem to have anti-inflammatory properties, according to the Mayo Clinic. That said, more research needs to be done to understand these effects.

The average western diet contains far more omega-6 fatty acids than our bodies need because these fats are found in processed seed and vegetable oils.

Benefits of Omega-6

It supports the health of your bones, stimulates hair growth, regulates metabolism and maintains your reproductive system.

Linoleic acid is an omega-6 fatty acid, according to the National Library of Medicine, which helps form cell membranes, especially in your skin. Linoleic acid also produces prostaglandins, which are hormone-like lipids that help your blood clot, induce inflammation and control muscle contraction.

Sources of Omega-6

Because it's such a common ingredient in foods eaten in the U.S., soybean oil is the largest source of omega-6 fatty acids. Because omega-6 fatty acids are so prevalent, it's not included in fish oil supplements.


Some experts recommend working to limiting your intake of foods high in omega-6s to balance the optimal ratio of omega-3 to omega-6, per June 2006 research in the American Journal of Clinical Nutrition. (More on that below.)

To help limit your omega-6 fatty acid intake, focus on reducing processed foods and limiting cooking oils highest in omega-6, per Penn State:

  • Sunflower oil
  • Corn oil
  • Soybean oil
  • Cottonseed oil

Omega-6 fats provide your body with energy. They are essential fats, which means you need to get them from your diet, but most Americans get too much omega-6 from processed foods. The best sources of omega-6s are cooking oils such as sunflower, soybean and corn oils.

What Is Omega-9?

Omega-9 is a monounsaturated fat found primarily in vegetable sources, especially olive oil.

Unlike omega-3 and omega-6 fatty acids, omega-9s are not considered essential and can be made and used in your body, according to UCCS.

Benefits of Omega-9

Oleic acid is the primary omega-9 fatty acid. It has benefits for your heart and brain and is linked to a reduced risk of heart disease and stroke.

The oleic acid in omega-9 was found to have a significant effect on mood and behavior, according to a February 2013 study in the ​American Journal of Clinical Nutrition​. When dietary saturated fat was replaced with oleic acid, participants noticed a reduction in feelings of anger and hostility, as well as an increase in energy.

Sources of Omega-9

Omega-9 fatty acids are found mostly in vegetable oils and nuts, per the FDA, including:

  • Olives and olive oil
  • Avocados and avocado oil
  • Almonds and almond oil
  • Pecans
  • Cashews


Omega-9 fats are important for your heart and brain, and are not considered essential fats, which means your body can make them on its own. The best sources of omega-9s are vegetable oils and nuts as well as olives and olive oil and avocado and avocado oil.

Possible Side Effects of Fish Oil

The NIH warns that getting 900 milligrams a day of EPA plus 600 milligrams a day of DHA or more for several weeks might reduce immune function.

Other potential side effects from fish oil include:

  • An unpleasant taste
  • Heartburn
  • Bad breath
  • Nausea and stomach pain
  • Headache
  • Diarrhea
  • Smelly sweat

Does Fish Oil Thin Your Blood?

Fish oil is a blood thinner, which can be both positive and negative. Because fish oil decreases the time your blood clots, it is important to discuss taking the supplement with a medical doctor.

Fish oil is made up of omega-3 essential fatty acids. Normally, blood platelets' sticky surface causes blood to form together and clot. Fish oil supplements decrease blood platelet activity, resulting in slower blood clotting and thinner blood.

Blood clots might form in the body's arteries, leading to blocked blood flow and oxygen. Fish oil decreases the number of dangerous blood clots forming, lessening your risk of heart attack and stroke.

Does Fish Oil Raise LDL?

Maybe you've heard that fish oil can raise LDL, or perhaps you've heard the opposite, that fish oil can lower your LDL cholesterol.

There's strong evidence that omega-3s can reduce blood triglyceride levels. Omega-3s might also raise beneficial HDL cholesterol, although it might also increase harmful LDL cholesterol at the same time, per the Mayo Clinic.

A December 2020 study in Clinical Lipidology that looked at 9,253 people found no evidence that fish oil supplements raise LDL cholesterol.

Omega-3 (grams/day)

Omega-6 (grams/day)

People assigned male at birth (AMAB)

1.6 g

17 g

People assigned female at birth (AFAB)

1.1 g

12 g

People AMAB over 50


14 g

People AFAB over 50


11 g

Pregnant and Breastfeeding

1.3 to 1.4 g

13 g

There's no recommended daily intake for omega-9s because they are not essential fats and your body can produce them on its own.

The Dietary Guidelines recommend a daily intake of omega-3s for adults in the form of ALA, according to the Linus Pauling Institute. The average intake of omega-6 fats in the United States is 17 to 20 grams a day for adults AMAB and 12 to 13 grams a day for adults AFAB.

Balancing Omega-3 and 6 Fatty Acids

Although omega-3 and omega-6 fatty acids are important fats in your diet and have many health benefits, it's essential that they be taken in the right balance to be the most effective.

Over the course of time, the human diet has evolved away from a diet equally balanced with omega-6 and omega-3 fatty acids. Now, the typical American eats far more omega-6s than omega-3s, due to dietary changes and refinement of food over the last 100 years or so.

Although omega-6s are important for lowering LDL ("bad") cholesterol, high amounts or high ratios of omega-6s to omega-3s can increase inflammation, per Mount Sinai.

A March 2016 study in ​Nutrients​ assessed the effect that the ratio of omega-6 to omega-3 has on weight gain and obesity. Researchers noted that an imbalanced omega-6 to omega-3 ratio is linked to atherosclerosis, obesity and diabetes while diets richer in omega-3 are associated with lower incidences of these diseases.

The study also found that high omega-6 levels were linked to an increase in insulin resistance and weight gain, whereas omega-3 levels were associated with lower rates of obesity. The conclusion was that a balance of omega-6 to omega-3 in a 1-1 to 2-1 ratio is recommended for managing obesity.

Should You Take Fish Oil Supplements?

Many wonder if fish oil is worth it. If you don't eat much fish or seafood, taking an omega-3 fish oil supplement may help to effectively balance the omega-3 to -6 ratio. Omega-3 fish oil liquid is commonly found in supplements in the form of fish oil capsules or soft gel forms, per the Mayo Clinic.

Fish oil is extracted from cold-water fish, including salmon, mackerel, herring and cod. The substance contains a blend of omega-3 fatty acids made up of EPA and DHA.

There are risks associated with fish oil supplements: Taking fish oil could cause problems within the digestive system, including indigestion, nausea and loose stools, especially in people who already have GI issues, per the Mayo Clinic.

While there's no exact recommended dosage for omega-3s, per the NIH, we do know that an absence of this essential nutrient is associated with a number of chronic conditions, including heart disease, mood disorders and certain cancers, according to Harvard Health Publishing.

Liquid Fish Oil vs. Capsules

Capsules offer several advantages, but those who have difficulty swallowing capsules may still prefer the liquid form.

Whether you plan to use liquid or capsules, always consult with your doctor first because people on certain medications or those with seafood allergies or various medical conditions may not be able to take fish oil.

Liquid Fish Oil Pros

  • People who have difficulty swallowing large pills or capsules might prefer liquid fish oil, which goes down your throat more easily. As refinement and filtering procedures have improved, fish oil has become far more palatable, and many manufacturers market fish oil that is sweetened and flavored to improve palatability.
  • You can add the fish oil to a salad or mix it into juice or a smoothie to further mask the flavor.

Liquid Fish Oil Cons

  • Once it has been opened, liquid fish oil is more vulnerable to going rancid. Exposure to light, heat and air expedites the oxidation of the oil, and oxidized fish oil may raise levels of LDL cholesterol, per ConsumerLab. Once you open a bottle of liquid fish oil, store it in a dark place to help prevent it from going rancid.

Fish Oil Pills Pros

  • Many people find it easier to swallow odorless, flavorless fish oil capsules than to swallow strongly flavored liquid fish oil.
  • Fish oil capsules contain the fish oil in airtight capsules, which reduces the risk of oxidation and enhances the shelf life of the oil.
  • Dosaging is fairly straightforward with capsules; once you determine how many pills you need to take for your condition or purpose, you simply count out the pills.

Fish Oil Pills Cons

  • A small number of people have allergic reactions to the gel capsule, which is made from the same substance as gelatin. Many gel capsules are made from body parts of pigs and cows, making them non-kosher and off-limits for certain people.


  • For those who experience gastrointestinal side effects of fish oil, such as heartburn, look for products with the fat-digesting enzyme lipase, which may help prevent fishy reflux, according to the Arthritis Foundation.
  • If you freeze the capsules before taking them, even more of the oil is released in your lower intestine rather than your stomach, which further reduces side effects.

Fish Oil for Pregnant People

Quality fish oil is safe to take during pregnancy, according to the American Pregnancy Association. Pregnant people are especially in need of omega-3s, as they become depleted because the fetus uses them for its nervous system development.

Research has found that adding EPA and DHA to pregnant people's diets supports the visual and cognitive development of the baby, according to the American Pregnancy Association. Sufficient amounts of omega-3s are also linked to improved symptoms of post-partum depression, though more research is needed.


The American Pregnancy Association recommends looking for one that follows quality standards during the manufacturing process, including the Norwegian Medicinal Standard, the European Pharmacopoeia Standard and the voluntary U.S. standard.

Talk to your doctor about the recommended dosage for you.

Fish Oil for Kids

Omega-3 fatty acids are critical for a child's brain function and overall growth and development. The recommended daily dose of omega-3 for kids depends on the age and medical condition of the child.

Dosage should be determined with the individual needs of the child in mind and only after consulting with the child's doctor or other health care provider.

For infants under 9 months of age, breast milk provides an average omega-6 to omega-3 ratio of 2:1. For older infants and children, fatty fish like wild-caught salmon, tuna or halibut provide both EPA and DHA omega-3 fats. Flaxseed oil, nuts and nut oil contain omega-3 fat in the form of ALA and are also great options.

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