The areca nut ( or ) is the seed of the areca palm (Areca catechu), which grows in much of the tropical Pacific, Asia, and parts of east Africa. It is commonly referred to as betel nut, as it is often chewed wrapped in betel leaves (paan). The term areca originated from a South Asian word during the 16th century, when Dutch and Portuguese sailors took the nut to Europe. The habit has many harmful effects on health. The International Agency for Research on Cancer concluded after reviewing the published medical research that chewing areca nut is carcinogenic to humans. Various compounds present in the nut, most importantly arecoline (the primary psychoactive ingredient), contribute to histologic changes in the oral mucosa. As with chewing tobacco, its use is discouraged by preventive efforts, such as awareness of the risks of chewing buai.