When it comes to fat, there's one type you don't want to cut back on: omega-3 fatty acids. Two crucial ones -- EPA and DHA -- are primarily found in certain fish. ALA (alpha-linolenic acid), another omega-3 fatty acid, is found in plant sources such as nuts and seeds. Not only does your body need these fatty acids to function, but also they deliver some big health benefits.

How They Help Your Health

Blood fat (triglycerides). Fish oil supplements can lower elevated triglyceride levels. Having high levels of this blood fat puts you at risk for heart disease and stroke.

Rheumatoid arthritis. Fish oil supplements (EPA+DHA) may curb stiffness and joint pain. Omega-3 supplements also seem to boost the effectiveness of anti-inflammatory drugs.

Depression. Some researchers have found that cultures that eat foods with high levels of omega-3s have lower levels of depression. The effects of Fish oil supplements on depression has been mixed. More research is needed to see if it can make a difference.

Baby development. DHA appears to be important for visual and neurological development in infants.

Asthma. A diet high in omega-3s lowers inflammation, a key component in asthma. But more studies are needed to show if fish oil supplements improve lung function or cut the amount of medication a person needs to control the condition.

ADHD. Some studies show that fish oil can reduce the symptoms of ADHD in some children and improve their mental skills, like thinking, remembering, and learning. But more research is needed in this area, and omega-3 supplements should not be used as a primary treatment.

Alzheimer's disease and dementia. Some research suggests that omega-3s may help protect against Alzheimer's disease and dementia, and have a positive effect on gradual memory loss linked to aging. But that's not certain yet.