Arecoline exists in the peel and kernels of areca nuts in a bound form with tannic acid. It dissociates from tannic acid at a pH of approximately 11, a level that ordinary edible alkalis cannot reach. Only slaked lime can achieve such a high pH value. Nowadays, food-grade slaked lime, chemically known as calcium hydroxide, is widely used as an acidity regulator by all manufacturers of edible areca nuts. Once dissociated, arecoline is rapidly absorbed by the human body and then stimulates the nerves to produce an excitatory effect. This is the physiological effect of arecoline, one of the main reasons for chewing areca nuts, and also explains why slaked lime is always used together with areca nuts when chewing them.