A double-blind, placebo-controlled study found taking fish oil and multivitamins together had added benefits over just taking fish oil alone. Published in Nutrients, the study investigated how different dosages of fish oil, taken with or without multivitamins, affected the incorporation of omega-3 fatty acids into red blood cells. Researchers found that the omega-3 index (a measure involving total, combined amounts of the fatty-acids EPA, DHA, and DPA) increased only in the study participants receiving 6 grams of fish oil daily with a multivitamin, as compared to the placebo group. In addition, researchers noted that women were generally better able to incorporate long-chain omega-3s into red blood cells, suggesting that future recommendations for fish oil supplements might need to be gender-specific. These particular findings are consistent with other research that has found males and females may respond differently to omega-3 supplementation, although it is one of the few so far to examine the effects of fish oil and multivitamins taken in combination.