Osmolyte

A compound that is accumulated or excreted by cells to regulate intracellular osmolarity — the concentration of solutes inside the cell — in response to changes in the external environment. Osmolytes help cells maintain volume and function under osmotic stress (e.g. dehydration, salt stress, heat). Taurine (Section 34) and betaine anhydrous (Section 47) are both osmolytes; betaine's accumulation in kidney cells is one of the reasons it was originally studied as a dietary component in kidney health before its sports nutrition applications were investigated.