Fish Oil Omega-3: benefits and risks of supplements

Getting enough omega-3 fatty acids can help keep your heart, eyes, brain, and other parts of your body healthy. Research into nutritional supplements has shown mixed results.

On this page: 

1. What are omega-3s?
2. Alpha-linolenic acid (ALA)
3. Eicosapentaenoic Acid (EPA)
4. Docosahexaenoic Acid (DHA)
5. Benefits of omega-3
6. Does Omega-3 Improve Brain Function and Memory?
7. Is omega-3 good for heart health?
8. Does omega-3 support eye health? 
9. Omega-3 sources
10. Risks of using omega-3 supplements
11. Summary

Omega-3 fatty acids are important fats that you should get from your diet. 

Fish oils come from fatty or oily fish, such as trout, mackerel, tuna, herring, sardines, and salmon. They contain omega-3 fatty acids, and many of them contain vitamins A and D. 

Many people use fish oil and omega-3 supplements because they believe they have health benefits. But, most people don’t know what they are. 

This article explains everything you need to know about omega-3 fatty acids, including the different types, their benefits, and omega-3 supplements. 

What are omega-3s?

Omega-3s are fatty acids that play important roles in your body and may provide(1) many health benefits for your heart, eyes, and brain. 

The three main types are: 

• ALA (alpha-linolenic acid)

• DHA (docosahexaenoic acid)

• EPA (eicosapentaenoic acid) 

ALA is found primarily in plants, while DHA and EPA are mostly found in animal foods and algae.

Since your body can’t produce them on its own, you must get them from your diet. 

Common foods that are high in omega-3 fatty acids include fatty fish (mackerel, tuna, salmon), fish oils, flaxseeds, chia seeds, flaxseed oil, walnuts, and almonds. 

For people who don’t eat many of these foods, omega-3 supplements, such as fish oil or algae oil, are recommended. 

In short, omega-3 fatty acids are a group of essential fats that you must get from your diet. There are three main types of fatty acids: ALA, EPA, and DHA. Your body does not make omega-3 acids. 

Alpha-linolenic acid (ALA)

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

ALA is converted to EPA or DHA, but only a small percentage(2), when ALA isn’t converted to EPA or DHA, is simply stored or used for energy like other fats. 

The conversion rate is greater in women than(3) in men, possibly due to the regulatory role of estrogen in women.

One study suggests(4) that a diet high in ALA is linked to a lower risk of death from heart disease. 

Other studies show an increased(5) risk of prostate cancer, but not the other major omega-3s, EPA and DHA, which appear(6) to protect against this cancer. 

ALA is found in many plant-based foods, including kale, spinach, soybeans, almonds, and many seeds, such as chia, flax, hemp, and kale, which are high in ALA. 

Eicosapentaenoic Acid (EPA)

Eicosapentaenoic acid is an omega-3 fatty acid. EPA plays an important role in reducing chronic inflammation(7) and depression and is involved in the body’s physiology. 

Your body uses EPA to produce signaling molecules called eicosanoids that help provide many benefits, including: 

• Reducing chronic inflammation

• Reducing depression

• Decrease in heart disease

• Reducing menopausal symptoms

Chronic, low-level inflammation is known to drive many common diseases. 

Studies(8) in Japanese people, who are known to eat a diet rich in seafood, have shown longer life expectancy and a lower risk of cardiovascular disease than Western populations, which is at least partly related to their high fish intake.

One study suggests(9) that fish oil, which is high in EPA and DHA, may reduce symptoms of depression. 

There is some evidence that EPA is superior(10) to DHA in reducing symptoms of depression. 

One study(11) in postmenopausal women found that EPA significantly reduced the number of hot flashes they had.  

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

EPA is highest in salmon, herring, eel, shrimp, and sturgeon. Animal products, such as dairy products and meat, also contain some EPA.

Docosahexaenoic Acid (DHA)

Docosahexaenoic acid is important for brain development and may protect against heart disease, cancer, and other health problems.

DHA benefits include(12):

• Contributes to the formation(13) of the retina

• Improves(14) vision in infants

• Improves brain function and development in children

• Arthritis

• Digestive diseases

• Lowers blood pressure

• Heart health

• Diabetes

• Some types of cancer

DHA is essential for building and improving brain function in childhood and in adults.

Low DHA is associated(15) with poor brain function and the onset of Alzheimer's disease in adults.

DHA deficiency early in life, such as in infants and children, is associated(16) with learning disabilities, attention deficit hyperactivity disorder, and aggressive behavior.

Furthermore, it can promote(17) heart health by reducing blood triglycerides and possibly LDL (bad) cholesterol. 

You can get DHA in large amounts from seafood, including fatty fish and algae. 

What are the potential health benefits of omega-3? 

Researchers have linked omega-3s to a number of health conditions. However, it’s not always clear whether taking omega-3 supplements can provide benefits.

Some of the health benefits that omega-3s, especially from dietary sources, may provide include: 

Multiple sclerosis

Some people with multiple sclerosis take omega-3s because they may have protective effects on the brain and nervous system. 

However, at least one study(18) has concluded that omega-3 supplements do not reduce disease activity in MS. 

Reducing COVID-19 risk

A 2020 study(19) suggested that women who took probiotics, vitamin D, fish oil supplements, or a combination of these supplements may have a slightly lower risk of getting COVID-19. 

In fact, experts have cautioned against using supplements to try to prevent the virus. 

Reducing menopausal symptoms

Omega-3 fatty acids help relieve menopausal symptoms in women. 

A study(20) in 2019 on taking omega-3 with vitamin D for menopausal women found that taking the two substances increased estrogen levels and thus reduced symptoms.

Preventing prostate cancer

Some research has shown(21) that eating a diet rich in omega-3s may help prevent prostate cancer.

However, a 2013 study(22) suggested that consuming large amounts of fish oil may actually increase the risk of high-grade prostate cancer. 

The exact link(23) between omega-3s and different types of cancer remains unclear. 

However, the option of eating plant-based omega-3 remains good for preventing prostate cancer, such as moringa, for example.

Reducing the risk of postpartum depression

 Taking omega-3s during pregnancy and breastfeeding is important for reducing depression. 

The authors of a 2018 review(24) concluded that taking fish oil supplements may help reduce the risk of postpartum depression. 

Therefore, it is recommended to eat light canned tuna, salmon, pollock, and catfish. Avoid eating(25) fish that contain high levels of mercury, such as king mackerel and shark. 

Take Omega-3 with exercise, especially new ones , as walking backwards . 

Fight inflammation and osteoporosis

Inflammation is the body's natural response to all types of infections and damage to your body. 

Omega-3 fatty acids reduce the production of molecules and substances associated with inflammation, and they play a role in strengthening your immunity and anti-inflammatory.

Omega-3, magnesium and calcium may treat arthritis, especially degenerative arthritis, and reduce the risk of osteoporosis.  

May improve bone strength and joint health.

Healthy fetal development 

Omega-3 intake during the fetal development stage in the mother’s womb is important for building the brain, nervous system, and body organs. 

Taking omega-3 may help(26) promote fetal development, especially the brain and eyes. This is why experts recommend eating oily fish during pregnancy. 

However, it is recommended to avoid eating fish that contain high levels of mercury, such as shark and king mackerel, during this time due to the negative effects of mercury. 

A study(27) in 2011 concluded that taking omega-3 during pregnancy may improve memory function in children later after birth. 

Relieves asthma cases  

Omega-3 fatty acids may have the ability to reduce IgE production. IgE antibodies can cause allergies and asthma.

Therefore, consuming foods rich in omega-3 fatty acids and vitamin C is known to be beneficial for bronchial allergies, may alleviate asthma cases.

Eating some of seeds, such as oatmeal, can relieve asthma symptoms. <

Does Omega-3 Improve Brain Function and Memory?

Omega-3 fatty acids are essential nutrients for brain function and dementia. 

Some studies(28) suggest that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may help treat a number of neurological and psychiatric conditions. These include: 

• Attention deficit hyperactivity disorder (ADHD)

• Cognitive decline, including memory loss

• Parkinson's disease

• Depression

• Dementia

• Post-traumatic stress disorder

• Schizophrenia

Some studies have suggested that omega-3 supplements may help prevent cognitive decline, especially in older adults. More research is needed to confirm these benefits.

Is omega-3 good for heart health?

Omega-3 fatty acids are important for heart function and support blood vessels against disease. 

Omega-3 fatty acids found in fish oils may help prevent heart disease and stroke. 

In addition, omega-3 fatty acids may help manage(29): 

• Blood cholesterol levels

• Triglyceride levels

• Atherosclerosis

• High blood pressure 

A 2013 study(30) showed that people who took fish oil supplements for more than one month had better cardiovascular function. 

A 2012 study suggested(31) that fish oil, due to its anti-inflammatory properties, may help stabilize atherosclerotic lesions and prevent their progression. 

However, a 2012 review(32) of 20 studies involving nearly 70,000 people found no strong evidence linking fish oil supplements to a lower risk of heart attack, stroke, or death. 

The AHA recommends(33) eating fish, especially fatty fish such as salmon or tuna, at least twice a week, which may reduce the risk of cardiovascular disease, especially cerebrovascular disease.

Does omega-3 support eye health?

Eating a diet rich in omega-3 fatty acids supports retinal health and improves vision.

Some evidence suggests that getting enough omega-3s may help protect eye health.

In a 2012 study(34), mice that received omega-3 supplements for 6 months appeared to have better retinal function and a lower risk of age-related vision loss than mice that did not receive the supplements.

Omega-3 supplements are often recommended(35) by ophthalmologists to support eye health, although scientific evidence does not always support their use for this purpose.

In some cases, eating a healthy diet may be more beneficial than taking supplements, according to some researchers and health experts.

In a study(36) of 4,202 people in the Netherlands, researchers found that those who ate fresh fruits and vegetables and two servings of fish per week were less likely to develop age-related macular degeneration than those who did not eat the same diets.

Some people may use omega-3 supplements to treat dry eyes.

In 2018, a year-long study(37) of 349 people with dry eyes found no evidence that taking the supplements was more beneficial than taking a placebo for treating dry eyes.

Omega-3 sources

Omega-3 sources vary(38), as there are animal sources and plant sources that provide the body with all the omega-3 acids it needs.

The best way to consume nutrients is through food, unless the doctor recommends taking omega-3 supplements.

Plant sources of omega-3 fish oil are many, including: 

• Flaxseed oil

• Sesame seeds

• Chia seeds

• Canola oil

• Walnuts

• Almonds

• Soybean oil

• Okra

• Kidney beans

• Avocado

• Blueberries

Animal sources of omega-3 are mostly marine, including:

• Tuna, sardines, salmon

• Cod liver oil

• Oysters and shrimp

• Eggs

Many foods contain omega-3 fatty acids. Eating a diet rich in certain types of fish, seeds, and nuts can help you get more omega-3s. 

Risks of using omega-3 supplements

Most people who eat a healthy, balanced diet of both plants and animals do not need to use omega-3 supplements or any other dietary supplement. 

However, omega-3 supplements are unlikely to cause any serious side effects.

But it is important to consult your doctor before using them, as there may be some risks. These include: 

• Minor digestive problems such as indigestion, belching, or diarrhea

• Omega-3 supplements may interfere with medications that target blood clotting conditions, such as warfarin

• Cod liver oil is high in vitamin A. This vitamin can be toxic in large amounts

• People with fish or shellfish allergies are at risk if they take fish oil supplements

• Some fish products may contain contaminants from the ocean

It is important to buy omega-3 supplements from a reputable source to ensure quality and effectiveness. 

Eating a healthy, balanced diet that leans toward plants remains the best way to get omega-3 and achieve maximum health benefits.

Summary 

omega-3 fatty acids are an important component of your diet.  It protects you from heart, bone, and brain diseases, and prevents cancer and asthma attacks. Take it regularly to prevent these diseases.