A study published in the Journal of Clinical Lipidology found that higher levels of EPA and DHA in red blood cells were associated with a lower risk of all-cause mortality in postmenopausal women. Over a 15-year period, the research analyzed data from more than 6,500 women ages 65 to 80 found omega-3 blood levels in the highest quartile were 20 percent less likely to die from any cause than those in the lowest quartile.
In the Women’s Health Initiative Memory Study, omega-3 levels were measured in 1996 and then the health outcomes were tracked through August 2014, with the primary outcome being all-cause mortality. After a median of 14.9 years of follow-up, 28.5 percent of the women had passed away. The analysis was adjusted for a wide variety of lifestyle and other factors such as smoking, physical activity and history of cardiovascular disease. This was a prospective cohort study, or a study that follows a group of similar people (a cohort) over time to observe correlations between various factors and health outcomes. Although this study was observational, the authors estimated that intakes of approximately 1g of EPA and DHA per day were required to increase omega-3 status from the lowest quartile observed in this study (3.6%) to the highest quartile (7.1%). This approximately equals two and a half to three salmon fillets per week or 1-3 softgels or one teaspoon of a liquid omega-3 supplement daily.