Omega-3 fatty acids are essential fats that have numerous health benefits.

However, not all omega-3s are created equal. Among 11 types, the 3 most important are ALA, EPA, and DHA.

ALA is mostly found in plants, while EPA and DHA are mostly found in animal foods like fatty fish.

This article takes a detailed look at the 3 most important types of omega-3s.

3 Types of Omega-3Share on Pinterest

Omega-3s are a type of polyunsaturated fat. They’re deemed essential fatty acids because they’re necessary for health but cannot be made by your body.

Thus, you must get them from your diet.

Rather than being stored and used for energy, they play important roles in many bodily processes, including inflammation, heart health, and brain function.

Omega-3 deficiency is associated with lower intelligence, depression, heart disease, arthritis, cancer, and many other health problems (1, 2).

SUMMARY Omega-3 fatty acids are a group of polyunsaturated fats that you must get from your diet. They have numerous health benefits.

Alpha-linolenic acid (ALA) is the most common omega-3 fatty acid in your diet.

It’s mostly found in plant foods and needs to be converted into EPA or DHA before it can be utilized by your body for something other than energy.

However, this conversion process is inefficient in humans. Only a small percentage of ALA is converted into EPA — and even less into DHA (3, 4, 5, 6).

When ALA is not converted to EPA or DHA, it is simply stored or used as energy like other fats.

Some observational studies link a diet rich in ALA to a reduced risk of death from heart disease, while others show an increased risk of prostate cancer (7).

This increase in prostate cancer risk was not associated with the other main omega-3 types, EPA and DHA, which seem to protect against this cancer (8).

ALA is found in many plant foods, including kale, spinach, purslane, soybeans, walnuts, and many seeds, such as chia, flax, and hemp. It also occurs in some animal fats.

Some seed oils, such as flaxseed and rapeseed (canola) oil, are also high in ALA.

SUMMARY ALA is mostly found in plant foods. Your body can convert it into EPA or DHA, though this process is highly inefficient.

Your body uses eicosapentaenoic acid (EPA) to produce signaling molecules called eicosanoids, which play numerous physiological roles and reduce inflammation (9).

Chronic, low-level inflammation is known to drive several common diseases (10).

Various studies indicate that fish oil, which is high in EPA and DHA, may reduce symptoms of depression. Some evidence suggests that EPA is superior to DHA in this regard (11, 12).

One study in menopausal women noted that EPA reduced their number of hot flashes (13).

Both EPA and DHA are mostly found in seafood, including fatty fish and algae. For this reason, they are often called marine omega-3s.

EPA concentrations are highest in herring, salmon, eel, shrimp, and sturgeon. Grass-fed animal products, such as dairy and meats, also contain some EPA.

SUMMARY EPA is an omega-3 fatty acid that can reduce symptoms of depression and help fight inflammation in your body.

Docosahexaenoic acid (DHA) is an important structural component of your skin and the retinas in your eyes (14).

Fortifying baby formula with DHA leads to improved vision in infants (15).

DHA is vital for brain development and function in childhood, as well as brain function in adults.

Early-life DHA deficiency is associated with problems later on, such as learning disabilities, ADHD, and aggressive hostility (16).

A decrease in DHA in later life is also linked to impaired brain function and the onset of Alzheimer's disease (17).

DHA may have positive effects on certain conditions, such as arthritis, high blood pressure, type 2 diabetes, and some cancers (18, 19, 20).

What’s more, it can boost heart health by reducing blood triglycerides and possibly your number of LDL (bad) cholesterol particles (21).

As mentioned above, DHA is found in high amounts in seafood, including fatty fish and algae. Grass-fed animal products also contain some DHA.

SUMMARY DHA is very important for brain development and may protect against heart disease, cancer, and other health problems.

ALA, the most common omega-3 fat, is not biologically active until it’s converted into EPA or DHA, which are essential for your body (3).

However, this conversion process is inefficient in humans. On average, only 1–10% of ALA is converted into EPA and 0.5–5% into DHA (4, 5, 6, 22).

Furthermore, the conversion rate depends on adequate levels of other nutrients, such as copper, calcium, magnesium, zinc, iron, and vitamins B6 and B7. The modern diet, especially vegetarianism, lacks some of these (23).

In addition, some omega-6 fatty acids compete for the same enzymes needed for this process. Therefore, the high amount of omega-6 in the modern diet may reduce the conversion of ALA to EPA and DHA (5, 24).

SUMMARY Other than being used for energy, ALA is not biologically active in your body. It needs to be turned into EPA and/or DHA to become active, but this conversion process is inefficient in humans.

ALA, EPA, and DHA are the most abundant omega-3 fatty acids in your diet.

However, at least eight other omega-3 fatty acids have been discovered:

  • hexadecatrienoic acid (HTA)
  • stearidonic acid (SDA)
  • eicosatrienoic acid (ETE)
  • eicosatetraenoic acid (ETA)
  • heneicosapentaenoic acid (HPA)
  • docosapentaenoic acid (DPA)
  • tetracosapentaenoic acid
  • tetracosahexaenoic acid

These fatty acids occur in some foods but are not considered essential. Yet, some of them do have biological effects.

SUMMARY At least eight other omega-3 fatty acids have been discovered. They’re found in some foods and may have biological effects.

The most important omega-3s are EPA and DHA.

They’re mainly found in seafood, including fatty fish and algae, meat and dairy from grass-fed animals, and omega-3-enriched or pastured eggs.

If you don't eat a lot of these foods, you may want to consider supplements.

SUMMARY EPA and DHA are generally considered the most important omega-3 fatty acids.

Omega-3 fatty acids are essential to maintain good health.

The most important types are EPA and DHA, which are abundant in fish oil, fatty fish, and many other seafoods. Algal oil is a good option for vegetarians and vegans.

Notably, EPA and DHA can also be formed from ALA, which exists in certain high-fat plant foods, such as flax seeds, flaxseed oil, walnuts, and chia seeds.

If you are eating inadequate amounts of omega-3-rich foods, supplements are generally recommended. You can easily buy them in stores or online.