Fish oil supplements are a good source of omega-3 fatty acids. These are polyunsaturated fats that are necessary for good health. The human body is not able to make omega-3 fatty acids, so they must come from the foods we eat or from supplements. Omega-3 fatty acids are known to help reduce pain and swelling and can prevent blood from forming clots easily. Other sources of omega-3 fatty acids include plant oils and nut oils.

Why fish oil is used
Fish oil contains DHA and EPA, which are two of the three common fatty acids. It is commonly used to treat or fight a variety of conditions:
• Triglycerides – Fish oil has been shown to be effective at lowering triglyceride levels from 20 to 50 percent.
• Heart disease – People with heart disease may be able to lower their risks of increasing damage from the condition by taking fish oil. People with healthy hearts may be able to prevent heart disease by taking fish oil. Some researchers believe fish oil is more effective at preventing heart attacks than “statin” medications.

Fish oil could be effective for a variety of other conditions which need further study including:
• High blood pressure
• Rheumatoid arthritis
• Menstrual pain
• ADHD
• Stroke
• Osteoporosis (brittle or weak bones)
• Bipolar and depression
• Weight loss
• Endometrial cancer
• Age-related macular degeneration

How fish oil is used
Fish oil can be consumed by eating certain fatty fish, or can be taken as a supplement. Most fish oil is obtained from mackerel, herring, tuna, halibut, salmon, cod liver, whale blubber, or seal blubber. Supplements may include vitamin E to prevent the oil from spoiling. Fish oil is often combined with calcium, iron, or vitamins A, B1, B3, B3, C, or D in supplements.

Cautions for fish oil
Low doses of fish oil is believed to be safe for most people, including women who are pregnant or breast-feeding. Cautions for fish oil include:
• Bleeding– Large doses of fish oil (3 grams or more per day) can prevent blood from clotting and cause excessive bleeding.
• Immune system – large doses of fish oil may depress the immune system and make it harder for the body to defend itself or fight infection.
• Cholesterol – Large doses of fish oil can increase levels of LDL (bad cholesterol).
• Contamination- Some fish can be contaminated by pollutants in the water, such as methylmercury.
• Food allergy – People who are allergic to fish should not take fish oil supplements
• Depression – Fish oil may increase feelings of depression.
• Birth control – Some studies show that taking birth control may limit fish oil’s ability to lower triglycerides levels.
• Blood pressure – Fish oil can cause blood pressure to decrease. It should not be taken in combination with any drugs used to lower blood pressure.

Health experts recommend eating fish at least twice a week.

Sources:
National Institutes of Health: Medline Plus
Mayo Clinic
American Heart Association