Although the full benefits of an adequate consumption of fish oil has not been completely determined the results of some published studies are compelling. Some of these studies certainly need confirmation in larger more scientifically robust studies before we can absolutely sure of their specific roles for certain diseases. The areas most interesting include:

Blood fat levels

Populations which tend to eat more oily fish tend to have lower cholesterol, lower LDL (bad fats) and higher HDL (good fats). Some fish oils have been approved by the U.S. Food and Drug Administration (FDA) for use in reducing blood triglyceride levels.

Immunity and Inflammation

A healthy immunity plays an vital important role in protecting us from infection and some cancers. Omega 3 & 6 provides many of the building blocks for the proteins and enzymes which make our complex immune structure including arachidonic acid, prostaglandin and interleukins. There are times, however, when our immune system mistakenly triggers an inflammatory response when no threat is present, leading to excess inflammation in your body. This causes diseases such as asthma, ulcerative colitis, rheumatoid arthritis, ulcerative colitis and crohn’s disease. There are other diseases which are probably linked to years of excessive inflammation but a link is more difficult to prove including, Alzheimer’s some, multiple sclerosis and even some cancers.

Several studies have linked adequate intake with a lower risk of inflammatory disease . For example, a study of mice feed a fish oil diet, compared with those fed corn oil, had decreased blood levels of markers of excessive inflammation (pro-inflammatory cytokines, tumour necrosis factor-alpha and interleukin-6) [Bhattacharya 2007]. In humans, a study published in the American Journal of Clinical Nutrition, 500 people had their dietary patterns analysed over several years. Those with the highest omega-3 intake had a 44% reduced risk of inflammatory disease.

Bone health (preventing osteoporosis)

Fish oil also contains vitamin D, which is important for healthy bones. A study by The University of Texas compared a corn oil rich diet (commonly present in Western diets) with a fish oil rich diet in mice. After 6 months the fish oil feed mice had significant better bone mineral density mice and lower osteoclast generation in bone marrow cell cultures (Bhattacharya 2007).

Brain health

The fats in our brain is 60% long chain omega 3 so it is logical to assume that chronic omega 3 deficiency will eventually lead to problems with cognitive development, learning ability, neuronal membrane plasticity, synaptogenesis, and neurogenesis, all of which are involved in synaptic transmission and the well-being of normal brain functions (Rinsho 2014). Despite not yet being 100% robust, numerous basic and epidemiological studies show that an increase in the consumption of omega-3 Fatty acids is likely to prevent the onset of neurophyschiatric illnesses.

Muscle health

Research has shows that supplementing the diet with fish oils may assist patients in maintaining muscle mass with advanced cancer on chemotherapy. Vera Mazurak, PhD, of the in Edmonton, set up a trial to compare the effects of fish oils on weight, muscle, and fat tissue in newly referred non-small cell lung cancer patients. The trail, from the University of Alberta, involved 24 non-fish oil consuming patients and 16 fish oil-consuming patients over a 10 week period. 2.3%, whereas the fish oil consuming patients on average maintained their muscle weight. (Blackwell 2011).

Improves fat burning

Despite fish oils having a lot of calories there intake has been linked to burning not weight gain by improving their metabolic rate. (Pitsavos 2006). In a randomised study, involving individual with metabolic syndrome (high triglycerides, insulin resistance and abdominal obesity) those who took omega-3 fish oil daily in combination with moderate aerobic exercise three times a week for 12 weeks had lower body fat stores, particularly abdominal fat.

Heart disease

It has always been well known that countries with the high fish and fish oil intake have low rates of heart disease even taking into account exercise, obesity and smoking (Gonzales 2014). This link was made more convincing after the publication of the Diet and Reinfarction Trial (DART) which showed that individuals who were advised to eat fatty fish (or who opted to take fish oil capsules instead) had a 29% reduction in cardiac mortality over the following two years compared with those not so advised (Burr 2005). There is some scientific evidence that fish oils seem to help to prevent a second heart attack especially if started within hours of the first attack and continued for a year.

Prostate cancer progression

A study of men already diagnosed with prostate cancer managed with active surveillance had a lower risk of progression if they have higher eicosapentaenoic acid (EPA) which is associated with higher fish oil and fish intake (Moorel et al). There are some concerns, however, within prostate cancer prevention studies. Not all the studies related to prostate cancer are favourable for higher omega three levels (see concerns about omega section).

Breast cancer prevention

35,000 postmenopausal women completed a 24-page questionnaire to evaluate their use of non-vitamin, non-mineral “specialty” supplements. The women in this study did not have a history of breast cancer and did not have breast cancer when they enrolled in the study. During six years of follow-up, 880 study participants developed breast cancer. Of the specialty supplements used by the women in this study, only fish oil was associated with a reduced risk of breast cancer. Risk of breast cancer was 32% lower among women who regularly used fish oil supplements.

Bowel cancer relapse

People who eat more fish, vegetables and less meat have a lower risk of bowel cancer but the benefits of fish also apply after a diagnosis. A multinational study from Michigan State University’s Breslin Cancer Centre involving 1,515 colon cancer patients from the United States, Poland, Vietnam and Western Europe found those who eat fish less than twice a week or exercise for less than an hour each week are about 2.5 times more likely to have a recurrence of their colon cancer, the researchers found.

Blood pressure

Studies have linked fish oils intake lower blood pressure in some people who are already taking have high blood pressure medication.

Protection from polluted air

A study in Environ Health Perspect 2012 shows that fish oil supplementation appeared to attenuate the adverse cardiac and lipid effects associated with air pollution exposure. This suggests fish oils as an important supplement if you live in the major cities (Tong 2012).

Arthritis

Fish oils have been found to reduce joint stiffness and improve mobility among individuals with rheumatoid arthritis. There is also some benefit for patients with osteoarthritis but the evidence is less robust.

Other conditions which fish oils are possibly effective for but robust evidence is lacking

  • Menstrual pain (dysmenorrhea).
  • Attention deficit-hyperactivity disorder (ADHD) in children.
  • Abnormal sensitivity to cold (Raynaud’s syndrome).
  • Depression, when taken with conventional antidepressant medications.
  • Weight loss.
  • Preventing eye disease (age-related maculopathy).
  • Dry eye syndrome.