Updated 7th June 2023

What are the health benefits of omega-3s?

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Omega-3 fatty acids are polyunsaturated fats in some plants and fish. They’re part of every cell in your body and play a role in making hormones. 

Omega-3s may have potential benefits in other areas, too, including heart health, brain health, and rheumatoid arthritis.

They’re essential fatty acids. This means that you need to get them from food because your body can’t make them.

Below, we look at seven of their possible health benefits, as well as the best ways to add omega-3s to your diet.

At ZOE, we run the largest nutrition science study in the world. We understand how eating specific foods and taking a personalized approach to nutrition can best support your health. Take our free quiz to learn more.

Health benefits of omega-3s

The three main omega-3s are:

  • alpha-linolenic acid (ALA)

  • docosahexaenoic acid (DHA)

  • eicosapentaenoic acid (EPA)

ALA is in plant foods, such as flax seeds and walnuts.

The best sources of DHA and EPA are cold-water fatty fish, like anchovies and salmon.

Food is the best way to get these omega-3 fats into your diet — but many of the studies looking at their possible effects have relied on supplements, such as fish oil.

Where it helps, we’ll explain the equivalent amount of food you’d need to get the amount of omega-3s in the supplements studied.

1. Heart health 

Eating more fish can lead to better heart health. Things are less clear when it comes to omega-3 supplements. 

A review of 79 clinical trials found little to no evidence that taking supplements containing EPA or DHA lowers the risk of a heart attack or dying from heart disease.

Elsewhere, another study involving people with high triglyceride levels found that those who took a form of EPA had better heart health outcomes than those who didn’t take EPA.

The participants were also taking medications called statins before the study began, and these drugs hadn’t been able to lower their triglyceride levels.

Research is a bit more promising when it comes to ALA. 

One review of population studies, involving almost 1.2 million participants, found an association between diets rich in ALA and a lower risk of death from heart disease.

The scientists also worked out that increasing your daily ALA intake by 1 gram — about the same as eating 0.5 ounces of walnuts or 1 tablespoon of canola oil — reduced the risk by 5%.  

Triglyceride levels

Having high levels of blood fats called triglycerides can increase your risk of heart disease. 

One large review of studies suggests that taking daily fish oil supplements may reduce your triglyceride levels.

Some doctors now prescribe daily doses of 2–4 g of EPA and DHA for people with high triglyceride levels. This is about what you’d get from eating 6 oz of herring (around 170 g) or two 3-oz servings of wild-caught salmon.

However, people with high triglyceride levels may also have an increased risk of a heart disorder called atrial fibrillation if they take omega-3 supplements. This disorder can raise your risk of stroke.

So, it may be that omega-3s only help with triglyceride levels if you get enough before your triglyceride levels rise too high.

2. Age-related macular degeneration

This is an eye disease that can impair your central vision by damaging part of your retina. There are high levels of DHA in retina cells. 

A review of multiple studies found that people with higher intakes of DHA and EPA, or fish, had much less risk of developing the condition than others. 

3. Dementia and brain health 

The omega-3 fatty acids in fish oil could benefit your brain later in life.

One review of existing research found that eating more omega-3s may help protect brain functions like focus and memory and reduce the risk of Alzheimer’s disease.

In the United Kingdom, one large study followed more than 215,000 people aged 60–73. It found that those who regularly took fish oil supplements had a lower risk of developing dementia than those who didn’t.

4. Inflammation

Chronic inflammation increases the risk of long-term health conditions like heart disease, stroke, and type 2 diabetes. 

A large “umbrella” analysis of 32 reviews found a link between regularly taking omega-3 supplements and a reduction in several indicators of inflammation, including the levels of certain proteins in blood.

5. Rheumatoid arthritis 

EPA and DHA could help reduce the symptoms of rheumatoid arthritis, an inflammatory disease that affects your joints.

In one small study, researchers found that participants who took fish oil supplements had less pain and fewer swollen joints after 12 weeks, compared with those who didn’t take the supplements.

Researchers have had similar results in smaller, older studies.

6. Depression 

Large studies of eating habits have found links between omega-3 fats and the risk of developing depression.

One study included more than 4,000 people in South Korea who had gone through menopause.

The researchers found an association between eating more omega-3 fatty acids and a lower risk of depression.

In a similarly sized study from Spain, researchers linked eating moderate amounts of fish and omega-3s with a reduced risk of depression — but not eating high amounts.

7. Child brain development

Omega-3s are very important for healthy development during pregnancy. Some limited research suggests that this may include the development of babies’ brains.

One trial found an association between taking supplements during pregnancy and improved early language development in children, along with further developmental improvements for boys. 

However, researchers reviewing multiple studies found only limited evidence of increased cognitive development and very little to suggest improvements in other, more specific measures.

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Best foods for omega-3s

Different foods contain different types of omega-3s.

The best sources of DHA and EPA are cold-water fatty fish, while you’ll find the highest levels of ALA in certain nuts, seeds, and plant oils.

Seafood sources of omega-3s

There are no official daily recommendations for DHA and EPA. But the Dietary Guidelines for Americans suggest eating at least 8 oz (around 227 g) of fish or seafood a week. 

The amount of omega-3s in different fish can vary greatly. Here are some options if you eat seafood:

  • salmon: 1.8 g of omega-3s in a 3-oz serving

  • herring: 1.7 g in a 3-oz serving

  • mackerel: 1 g in a 3-oz serving

  • rainbow trout: 0.8 g in a 3-oz serving

Farmed salmon often has more omega-3s than wild salmon. However, it can also contain high levels of antibiotics, so it may not be the healthiest fish choice

Plant sources of omega-3s

Experts recommend that adult females aim to get 1.1 g of ALA a day and that adult males get 1.6 g. People who are pregnant and breastfeeding need more.

Some good sources of ALA include:

  • flaxseed (linseed) oil: 7.3 g of ALA in 1 tbsp 

  • chia seeds: 5 g in a 1-oz serving

  • walnuts: 2.6 g in a 1-oz serving

  • flaxseeds: 2.4 g in 1 tbsp

  • canola (rapeseed): 1.3 g in 1 tbsp

  • soybean oil: 0.9 g in 1 tbsp

Take our free quiz to begin learning about which foods might be best for your body.

Do I need to take a supplement?

Most of us don’t need to take omega-3 supplements, like fish oil or krill oil. We’re able to get the omega-3s we need through food.

Not only do fish and plant sources of omega-3 fats contain an array of extra vitamins, minerals, and other nutrients, there’s also better evidence that they’re good for your health.

Still, some people might benefit from taking omega-3 supplements. They include:

  • Those who are pregnant and breastfeeding: DHA and EPA are important for healthy growth in babies. If you're concerned about eating fish while pregnant, your healthcare provider may recommend a supplement.

  • Older adults: As we mentioned earlier, there’s evidence that regularly taking omega-3 supplements later in life could help protect cognitive function and reduce the risk of dementia.

  • People who don’t eat seafood: If this is you, it’s difficult to get DHA and EPA without a supplement. Still, having a healthy, plant-based diet is already linked with a lower risk of heart disease, regardless of how many omega-3s you get.

Can you have too many omega-3s?

For most people, even relatively large amounts of omega-3s shouldn’t cause serious health issues.

Experts have concluded that taking daily omega-3 supplements containing up to 5 g total of EPA and DHA appears to be safe.

However, a very small number of people may find that smaller doses can cause digestive issues, like diarrhea or flatulence.

Frequently asked questions about omega-3s

Here’s what we know so far, in response to some common questions about omega-3s.

Before we dive in, it’s worth noting that the research in many of these areas is very limited.

Are omega-3s good for your hair?

It’s still unclear whether omega-3s are good for hair health.

In one study, scientists looked at the effects of supplements containing omega-3s on hair over 6 months.

The participants taking the supplements reported less hair loss, as well as denser, thicker hair growth, compared with those who didn’t take the supplements.

However, this was a very small study, so we need more research to back up these findings. We should also point out that Innéov, a group set up by L’Oréal and Nestlé, funded this research.

Are omega-3s good for your skin?

There’s some evidence that omega-3s, especially EPA and DHA, could play a role in regulating the function of the skin barrier, protecting skin from the effects of sunlight, and even helping with conditions like acne. 

However, much of this research comes from animal or test tube studies.

The trials that did include humans were often small or quite old, and they gave inconsistent results. 

What does omega-3 do for the female body?

DHA and EPA omega-3s are important for a healthy pregnancy. They may also help ease period pain and reduce the risk of depression for people who have gone through menopause.

Meanwhile, while overall results have been mixed, a recent review of studies found that getting more omega-3s, especially ALA, may improve bone health for women.

This could be helpful, as women experience the bone disease osteoporosis more often than men. 

Summary

Omega-3 fatty acids are essential for the healthy functioning of your body.

On top of this, these fats could help with your heart health, brain health, and inflammation levels. They may also ease the symptoms of conditions such as rheumatoid arthritis.

The best way to get enough omega-3s is by eating fatty fish, like mackerel and salmon, and certain plant foods, such as flaxseeds and walnuts.

Omega-3 supplements might be helpful if you don’t eat seafood, or if you’re pregnant, breastfeeding, or an older adult.

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