Fish oil has been used to treat hypercholesterolemia, a risk factor for heart disease. Fish oil is found in fresh fish but is also available as a supplement. Omega-3 fatty acids are the components in fish oil thought to have the most health benefits. Supplements can have side effects and should only be used after consulting with a physician.
Cholesterol
Cholesterol is a type of blood fat. Hypercholesterolemia is characterized by high cholesterol and is a risk factor for heart disease, heart attack and stroke. There are two main types of cholesterol---high-density lipoprotein (HDL) and low-density lipoprotein (LDL). HDL is referred to as "good" cholesterol because it removes excess cholesterol from the blood and is associated with a decreased risk of heart disease. LDL is considered "bad" cholesterol because it contributes to factors that lead to heart disease. Total cholesterol is calculated by adding HDL and LDL and should be below 200 mg/dL, according to the American Heart Association (AHA). Optimal HDL is above 60 mg/dL. Optimal LDL is between 100 and 129 mg/dL for most people and less than 70 mg/dL for people who are at risk for or have heart disease.
Omega-3 Fatty Acids
Fish oil contains omega-3 essential fatty acids that must be obtained through the diet. The two forms of omega-3 in fish oil are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). According to the Mayo Clinic and the University of Maryland Medical Center (UMMC), research has shown that omega-3s reduce inflammation and lower the risk of heart disease, cancer and arthritis.
Evidence
Fish oil supplements appear to result in small improvements in HDL, according to Medline Plus. While small increases in LDL have been observed with the use of fish oil, the American Heart Association says that high HDL can balance borderline-high total cholesterol. Evidence also shows that omega-3 fatty acids reduce triglycerides, another type of blood fat. According to the UMMC, triglycerides are often elevated when total cholesterol or LDL is high. The Mayo Clinic says that omega-3s reduce blood pressure and the risk of blood clots, other factors for heart disease. Fish oil also reduces the risk of sudden death in patients who have already had a heart attack.
Dosage
The AHA encourages people to eat fatty fish at least twice a week to prevent heart disease. Examples include mackerel, lake trout, herring, sardines, albacore tuna, salmon and halibut. Individuals who are unable to eat fish may consider taking fish oil supplements. The World Health Organization recommends 0.3-0.5 g of EPA and 0.8-1.1 g of DHA per day. According to the UMMC, fish oil supplements vary in their EPA and DHA content, but common doses found in fish oil capsules are 0.18 g of EPA and 0.12 g of DHA. Adults are not recommended to take more than 3 g of fish oil per day.
Side Effects
Common side effects of fish oil supplements include gas, bloating, belching and diarrhea. Omega-3s can increase the risk of bleeding and should be used cautiously by people who bruise easily, have a bleeding disorder or are on blood-thinning medications like coumadin or aspirin. Omega-3s can also lower blood sugar and should not be used by diabetics who take insulin or medications to lower blood sugar.
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