What is fish oil?
Fish oil is the fat or oil that’s extracted from fish tissue.
It usually comes from oily fish such as herring, tuna, anchovies, and mackerel. However it’s also sometimes produced from the livers of other fish, as is the case with cod liver oil.
The World Health Organization (WHO) recommends eating 1–2 portions of fish per week. This is because the omega-3 fatty acids in fish provide many health benefits, including protection against a number of diseases.
However, if you don’t eat 1–2 servings of fish per week, fish oil supplements can help you get enough omega-3s.
Around 30% of fish oil is made up of omega-3s, while the remaining 70% is made up of other fats. What’s more, fish oil usually contains some vitamin A and D.
It’s important to note that the types of omega-3s found in fish oil have greater health benefits than the omega-3s found in some plant sources.
The main types of omega-3s in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), while the type found in plant sources is mainly alpha-linolenic acid (ALA).
Although ALA is an essential fatty acid, EPA and DHA have many more health benefits.
It’s also important to get enough omega-3s because the Western diet has replaced a lot of omega-3s with other fats, such as omega-6s. This distorted ratio of fatty acids may contribute to numerous diseases.
- May support heart health
Heart disease is the leading cause of death worldwide.
Studies show that people who eat a lot of fish have much lower rates of heart disease.
Multiple risk factors for heart disease appear to be reduced by the consumption of fish or fish oil.
Although fish oil supplements can improve many of the risk factors for heart disease, there is no clear evidence that they can prevent heart attacks or strokes.
- May help treat certain mental health conditions
Your brain is made up of nearly 60% fat, and much of this fat is omega-3 fatty acids. Therefore, omega-3s are essential for typical brain function.
In fact, some studies suggest that people with certain mental health conditions have lower omega-3 blood levels.
Interestingly, research suggests that omega-3s can prevent the onset or improve the symptoms of some mental health conditions. For example, it can reduce the chances of psychotic disorders in those who are at risk.
In addition, supplementing with fish oil in high doses may reduce some symptoms of both schizophrenia and bipolar disorder, though there is a lack of consistent data available. More study is needed in this area.
- May support eye health
Like your brain, your eyes rely on omega-3 fats. Evidence shows that people who don’t get enough omega-3s have a greater risk of eye diseases.
However, this positive effect was not found for dry eye disease in particular.
Furthermore, eye health begins to decline in old age, which can lead to age-related macular degeneration (AMD). Eating fish is linked to a reduced risk of AMD, but the results from fish oil supplements are less convincing.
One older study found that consuming a high dose of fish oil for 19 weeks improved vision in people with AMD. However, this was a very small study.
Two larger studies in 2013 examined the combined effect of omega-3s and other nutrients on AMD. One study showed a positive effect, while the other found no effect. Therefore, the results are unclear.
- May reduce inflammation
Inflammation is your immune system’s way of fighting infection and treating injuries.
However, chronic inflammation is associated with health conditions such as obesity, diabetes, depression, and heart disease.
Reducing inflammation can help treat symptoms of these diseases.
Because fish oil has anti-inflammatory properties, it may help treat conditions involving chronic inflammation.
For example, increased weight or stress can sometimes contribute to higher levels of inflammation.
In two older studies — one in people with obesity and one in people experiencing stress — fish oil was found to reduce the production and gene expression of inflammatory molecules called cytokines.
Moreover, fish oil supplements can significantly reduce joint pain, stiffness, and medication needs in people with rheumatoid arthritis, which causes pain in the joints.
While inflammatory bowel disease (IBD) is also triggered by inflammation, there is no clear evidence to suggest that fish oil improves its symptoms.
- May support healthy skin
Your skin is the largest organ in your body, and it contains a lot of omega-3 fatty acids.
Skin health can decline throughout your life, especially during old age or after too much sun exposure.
That said, fish oil supplements may be beneficial in a number of skin disorders, including psoriasis and dermatitis.
- May support pregnancy and early life
Omega-3s are essential for early growth and development.
Therefore, it’s important to get enough omega-3s during pregnancy and while breastfeeding.
Taking fish oil supplements during these times may improve fetal brain development. However, it’s unclear whether learning or IQ will also be improved.
Taking fish oil supplements during pregnancy and breastfeeding may also improve infant visual development and help reduce the risk of allergies.
- May reduce liver fat
Your liver processes most of the fat in your body and can play a role in weight gain.
Liver disease is increasingly common — particularly nonalcoholic fatty liver disease (NAFLD), in which fat accumulates in your liver.
Fish oil supplements can improve liver function and inflammation, which may help reduce symptoms of NAFLD and the amount of fat in your liver.
- May improve symptoms of depression
Depression is expected to become the second-largest cause of illness by 2030.
Interestingly, older studies have shown that people with major depression appear to have lower blood levels of omega-3s. However, the results have been inconsistent so far.
Moreover, some studies have shown that oils rich in EPA help reduce depressive symptoms more than DHA. Again, more research is needed.
- May improve attention and hyperactivity in children
A number of neuro-developmental conditions in children, such as attention deficit hyperactivity disorder (ADHD), involve hyperactivity and inattention.
Given that omega-3s make up a significant proportion of the brain, getting enough of them may be important for preventing these conditions in early life.
Fish oil supplements may improve perceived hyperactivity, inattention, impulsiveness, and aggression in children. This may benefit early life learning. But more research is needed.
- May help prevent symptoms of mental decline
As you age, your brain function slows down and your risk of Alzheimer’s disease increases.
People who eat more fish tend to experience a slower decline in brain function in old age.
However, studies on fish oil supplements in older adults haven’t provided clear evidence that they can slow the decline of brain function.
Nevertheless, some very small studies have shown that fish oil may improve memory in healthy older adults.
- May improve asthma symptoms and allergy risk
Asthma, which can cause swelling in the lungs and shortness of breath, is becoming much more common in infants.
A number of studies show that fish oil may reduce asthma symptoms, especially in early life.
However, not all studies have found similar results.
In an older review in nearly 100,000 people, a mother’s fish or omega-3 intake was found to reduce the risk of asthma in children by 24–29%.
Furthermore, fish oil supplements in pregnant people may reduce the risk of allergies in infants.
- May improve bone health
During old age, bones can begin to lose their essential minerals, becoming more likely to break. This can lead to conditions such as osteoporosis and osteoarthritis.
Calcium and vitamin D are very important for bone health, but some studies suggest that omega-3 fatty acids can also be beneficial.
People with higher omega-3 intakes and blood levels may have better bone mineral density (BMD).
However, it’s unclear whether fish oil supplements improve BMD.
In one study, researchers found that omega-3 supplementation increased BMD in women with no symptoms or bone pain, but it did not appear to do so in women with osteoporosis. More research is needed (81 Trusted Source).
A number of small, older studies suggest that fish oil supplements reduce markers of bone breakdown, which may prevent bone disease.
Source: www.healthline.com
