Effects of omega-3 fatty acids on cardiovascular risk factors and intermediate markers of cardiovascular disease.

s that included only subjects who had a non-CVDrelated condition (e.g., cancer, schizophrenia, or organ transplant), letters, and abstracts. Upon review of full articles we excluded studies of children (under age 19 years), studies of daily omega-3 fatty acid doses of more than 6 g per day, studies of less than 4 weeks duration, crossover studies with less than 4 weeks washout between treatments, and studies that did not report complete data on outcomes of interest. We also excluded studies that did not report either the specific dose of omega-3 fatty acids or the amount of fish consumed and studies that reported only associations between omega-3 fatty acid tissue levels and risk factors. Specific sources of omega-3 fatty acid considered acceptable included fish oils, dietary fish, canola (rapeseed) oil, soybean oil, flaxseed or linseed oil, walnuts or walnut oil, and mustard seed oil. Other sources were eligible if omega-3 fatty acid levels were reported to be greater than the control. Because of the large number of studies available for analysis, for most outcomes of interest we confined analysis to the largest randomized trials for each outcome evaluated. For outcomes with few studies, all studies were included regardless of study design or sample size (minimum of five subjects). We limited our review of studies examining the association between dietary omega-3 fatty acid intake and tissue levels of omega-3 fatty acids to the larger randomized trials that met eligibility criteria for either intermediate or clinical outcomes.