For better heart health, experts suggests to take 250 milligrams as EPA/DHA from fish source a day. The American Heart Association suggests to take 1gram and 2 to 4 grams per day, respectively for people with documented heart disease or high levels of triglycerides.
The effect of fish oil supplements on blood lipoprotein was studied at the Norwegian University of Science and Technology in Norway observing 26 people with Type 2 diabetes. The participants were instructed to take either fish oil or corn oil supplements. After nine weeks of supplementation, size and concentration of lipoprotein subclasses and insulin sensitivity were measured. The results suggested that high doses of fish oil reduced the size and concentration of several lipoprotein subclasses while lowering the insulin sensitivity. Recent studies also suggest that fish oil may prevent dementia and help to ease depression.