A new study from Australia reports that an increase of blood omega-3 fatty acid concentration by fish oil intake seems to be more effective in females and at concurrent vitamin/mineral supplementation.
In the randomized controlled trial, the omega-3 and omega-6 fatty acid concentrations were measured in red blood cells of 160 healthy adult participants, aged between 50 to 70 years, who received either 6 g of fish oil (480 mg EPA and 480 mg DHA), 6 g of fish oil plus a multivitamin, 3 g of fish oil (240 mg EPA and 240 mg DHA) plus a multivitamin or a placebo daily for 16 weeks (1). The study results showed that the treatment with 6 g of fish oil led to a higher eicosapentaenoic acid (EPA) concentration in blood compared to the intake of 3 g fish oil, while docosahexaenoic acid (DHA) intakes had no effect on red blood cell composition. The omega-3 (EPA plus DHA) to omega-6 fatty acid (arachidonic acid, AA) ratio and the total omega-3 fatty acid (EPA plus DHA) concentration was only higher, compared to placebo, in the participant group receiving the combination of 6 g of fish oil and the multivitamin supplement. Analysis by gender revealed that all treat- ments increased EPA incorporation in females while, in males, EPA was only significantly increased by the 6 g fish oil multivitamin combination. There was considerable individual variability in the red blood cell incorpo- ration of EPA and DHA. Gender contributed to a large proportion of this variability with females generally showing higher blood omega-3 fatty acid concentrations after fish oil intake.
The researchers commented that recent studies suggested that males and females respond differently to omega-3 fatty acid supplementation across different health parameters (2, 3). Males and females may there- fore differ in their ability to incorporate omega-3 fatty acids into erythrocytes. Some males may incorporate relatively low amounts of omega-3 fatty acids into red blood cells despite adhering to intake guidelines, the scientists concluded. Moreover, some vitamins/minerals may aid the incorporation of omega-3 fatty acids into red blood cells: as cofactors vitamins, such as B vitamins, and minerals seem to influence the biosynt- hesis of omega-3 fatty acids, altering their blood levels (4). On the other hand, low levels of antioxidant vitamins may increase the risk of oxidative damaging (peroxidation) of lipids. As vitamin E (alpha-tocop- herol) is vital to the prevention of polyunsaturated fatty acid (PUFA) oxidation in cell membranes, it has been calculated that the intake requirement for alpha-tocopherol for PUFA protection is 12 to 14 mg per day (5). By preserving intracellular and cellular membrane integrity and stability, vitamin E plays an important role in the stability of red blood cells and conductivity in central and peripheral nerves (6).