Abstract
Cannabis use has increased sharply in the last 20 years among adults, including reproductive-aged women. Its recent widespread legalization is associated with a decrease in risk perception of cannabis use during breastfeeding. However, the effect of cannabis use (if any) on milk production and milk composition is not known. This narrative review summarizes current knowledge related to maternal cannabis use during breastfeeding and provides an overview of possible pathways whereby cannabis might affect milk composition and production. Several studies have demonstrated that cannabinoids and their metabolites are detectable in human milk produced by mothers who use cannabis. Due to their physicochemical properties, cannabinoids are stored in adipose tissue, can easily reach the mammary gland, and can be secreted in milk. Moreover, cannabinoid receptors are present in adipocytes and mammary epithelial cells. The activation of these receptors directly modulates fatty acid metabolism, potentially causing changes in milk fatty acid profiles. Additionally, the endocannabinoid system (ECS) is intimately connected to the endocrine system. As such, it is probable that interactions of exogenous cannabinoids with the ECS might modify release of critical hormones (e.g., prolactin and dopamine) that regulate milk production and secretion. Nonetheless, few studies have investigated effects of cannabis use (including on milk production and composition) in lactating women. Additional research utilizing robust methodologies are needed to elucidate whether and how cannabis use affects human milk production and composition.
To our knowledge, no review has focused on the potential effects of maternal cannabis use on human milk composition and production. The evidence provided herein supports the possibility that, through several well documented pathways, cannabinoids might alter lipid metabolism in the mammary gland, as well as milk production and secretion. Considering the recent increase in cannabis use among reproductive-aged women, this narrative review highlights the need for well designed, focused studies to address this question.