Cod Liver Oil & Vitamin D

Cod liver oil is extracted from cod fish liver. It is a concentrated source of omega-3 fatty acids and vitamins A and D. The omega-3 fatty acids in cod liver oil are of the long-chain type: eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA. These types of omega-3s are more potent than those found in terrestrial plants. Vitamin D is an important vitamin that is synthesized in the skin and is also found in oily fish, fish oil, egg yolks and milk.

Heart Disease

As the June 2011 issue of the "Journal of Pharmacy Practice" reports, fish oil supplements are beneficial for heart disease prevention and management. These supplements can lower blood triglycerides, prevent intravascular clots from forming, improve heart failure patients' status and improve circulation in diabetics. Fish oil supplements can also help decrease total cholesterol level and increase the levels of high-density lipoprotein cholesterol -- the beneficial cholesterol fraction.

Rheumatoid Arthritis

A review in the August 2010 issue of "The Proceeding of the Nutrition Society" documents that fish oil is beneficial in patients with rheumatoid arthritis. These patients often find that when they supplement with fish oil, they can decrease their use of non-steroidal anti-inflammatory drugs and still manage their condition. The authors say that this effect might be due to fish oil inhibiting pro-inflammatory substances in the body and enhancing the production of anti-inflammatory ones.

Neurological and Psychiatric Diseases

Omega-3 fatty acids are important for the proper function of the nervous system and the brain. Omega-3 supplementation may have a use in certain neurological and psychiatric pathologies. The January 2007 issue of "Progress in Neuro-Psychopharmacology and Biological Psychiatry" reports that emerging evidence supports the use of omega-3s in several psychiatric conditions and neurodegenerative diseases. Further studies are warranted.

Benefits of Vitamin D

Vitamin D is a fat-soluble vitamin that is synthesized in the skin on exposure to sunlight. However, vitamin D deficiency is not uncommon, especially during the winter months and in high latitude countries. This vitamin regulates calcium levels in the body and is therefore essential for healthy joints and teeth. It is also important in the maintenance of a healthy immune system and may be important in protecting against cancer, according to the "Manual of Dietetic Practice." Deficiency of vitamin D causes muscle and bone pain, and weak, fragile bones.