Treatment with estrogen compounds, such as oral contraceptive pills or oral estrogen replacement therapy, has been shown to increase levels of DHA in women, theoretically from the upregulation of DHA synthesis from dietary precursors (Giltay et al., 2004). Increased EPA and DHA in plasma due to hormone replacement therapy have been proposed to account for its antidepressant effects (Sumino et al., 2003). Should decline in endogenous estrogen levels, therefore, lower the amount of omega-3 fatty acids available to the brain, supplementation in the perimenopause may be of particular importance.