Cod liver oil has been used to improve people’s general health for centuries now. The oil contains Omega-3 fatty acids, and high amounts of vitamin A and D. Clinical tests have proven that cod liver oil helps prevent rickets in children and lowers the risk of heart disease. Cod liver oil is also good for the skin, hair, and nails.An interesting property of cod liver oil is that it can suppress inflammation. Normally, this is an unwanted side effect but for those suffering from rheumatoid arthritis, cod liver oil reduces the damage done by the inflammation to the joint cartilage.