Zymosthenic describes an agent that amplifies or strengthens the action of an enzyme — from the Greek zyme, leaven, and sthenos, strength. A zymosthenic substance does not catalyse the reaction itself but makes the enzyme work faster or more effectively, for example by stabilising its active form, supplying a needed cofactor, or removing an inhibitor. The concept appears in older enzymology literature, where distinguishing true coenzymes from mere activators refined the understanding of how enzymes are regulated. In practical fermentation, zymosthenic effects are exploited whenever brewers add yeast nutrients: the added minerals and vitamins do not ferment anything themselves, but the yeast’s enzymes work markedly better with them.