PhytoScience - Article

Fish Oil (Omega-3)

 

A type of polyunsaturated fatty acid (PUFA) derived mainly from fish oil. Anecdotally, omega-3 fatty acids are used to treat depression, hypercholesterolemia and to reduce the risk of heart attack.

A large survey of Finnish adults found that depressive symptoms were significantly higher among infrequent fish consumers and other studies have shown that individuals with major depression have marked depletions in omega-3 fatty acids.

Proported Uses

  • Asthma
  • Atherosclerosis
  • Cancer prevention
  • Cardiovascular disease
  • Colitis
  • Cystic fibrosis
  • Depression
  • High cholesterol
  • Schizophrenia

Mechanism of Action

Omega-3 fatty acids are a type of polyunsaturated fatty acid containing two or more double bonds in their acyl chain and a double bond on carbon number 3. Changes in omega-3 fatty acid levels have been associated with cardiovascular disease and depression. The cardioprotective effects of omega-3 likely come from its ability to be incorporated into and thereby enhance the stability of atherosclerotic plaques.

Omega-3 fatty acid does not seem to affect platelet function or coagulation. Increasing the intake of polyunsaturated fatty acids has been shown to increase lipid peroxidation. Supplementation with omega-3 fatty acids, therefore, may increase the oxidative stress on the body. Studies have shown that mucosal alpha-tocopherol levels decrease upon omega-3 supplementation which researchers believe may result from the body's attempt to counteract the added oxidative burden. Besides reducing serum anti-oxidant levels, little is known about how this added oxidative stress affects the body.

Omega-3 fatty acid supplementation has been shown to decrease IL-6 levels and tumor necrosis factor-alpha while leaving most other mononuclear cell functions unaffected. Omega-3 fatty acids may also reduce inflammation in patients with ulcerative colitis by reducing rectal dialysate leukotriene B4. Because of its anti-inflammatory effects, Omega-3 fatty acids have been thought to benefit patients with asthma and cystic fibrosis, however studies are inconclusive. Increasing PUFA intake in pregnant women increases PUFA concentration but not cytokine concentration in human milk.

Omega-3 fatty acid supplementation provides protection against ultra-violet radiation induced erythema and p53 expression, a biomarker of DNA damage

Adverse Reactions

Reported: Fishy aftertaste, loose stools and nausea after large doses.

Interactions

May increase the effect of other anticoagulant/antiplatelet agents. May reduce levels of alpha-tocopherol and beta-carotene. High levels of omega-3 fatty acids may decrease triglyceride and increase LDL cholesterol levels. Doses higher than 3 grams per day may increase bleeding time.

Clinical Summary

Omega-3 fatty acid supplementation lowered triglyceride levels in people with type 2 diabetes mellitus, however, low density lipoprotein cholesterol levels were increased. Omega-3 fatty acids may also help patients with ulcerative colitis and may reduce colon cancer risk. A systematic review of studies did not find a significant association between Omega-3 consumption and cancer incidence. But data from a prospective study suggest an association between fatty fish consumption and reduced occurence of renal cell carcinoma in women. However, conflicting results from another study point to increased risk of advanced prostate cancer with higher intake of alpha-linolenic acid in patients with low grade cancer

Omega-3 may be useful as a perioperative supplement as it lowers the magnitude of the body's inflammatory response. It has been shown not to reduce coagulation and platelet function after surgery. Omega-3 fatty acids can reduce sunburn sensitivity. Reviews of trials using omega-3 fatty acids have shown possible benefits for patients with cystic fibrosis, but no benefit for patients with asthma. Only mixed results were seen in patients with schizophrenia. Results from a recent clinical trial suggest that dietary supplementation with fish oil may help reduce the symptoms of systemic lupus erythematosus.

The FDA recommends that consumption of fish oils be limited to 3 grams or less per day as higher doses may increase the risk of bleeding

References

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Disclaimer:
These statements have not been evaluated by the FDA. Any product mentioned is not intended to diagnose, treat, cure or prevent any disease.