(a).

Enzyme	Food, beverage, or bioactive compounds Food sources in italics	Type of study	Dosages used and references
SULTs	Caffeine  Coffee, cocoa, black tea, and green tea [111]	In vivo	2, 10, and 50 mg/kg caffeine [107]
	Retinoic acid (bioactive form of vitamin A)   Meat (especially liver), fish, egg, and dairy products contain retinol; apple, apricot, artichokes, arugula, asparagus, and other plant foods contain provitamin A carotenes [111]	In vivo	2, 10, and 50 mg/kg/d retinoic acid suspension in corn oil [108]