Choline is an essential nutrient that plays important roles in human health. It provides methyl groups for many aspects of metabolism, is a component of cell membranes, and is used to produce acetylcholine, an important neurotransmitter for memory, mood, muscle control, and other nervous system functions. Choline is particularly important during pregnancy and breastfeeding, but some evidence suggests that choline supplementation could carry some risks. In this Aliquot, I talk about the science surrounding choline.