Safety and efficacy of Bixa orellana (achiote, annatto) leaf extracts

Bixa orellana leaf preparations have been used for many years by indigenous people for a variety of medicinal applications. Published research studies in animals indicate that various extracts of Bixa leaves exhibit antioxidant, broad antimicrobial (antibacterial and antifungal), anti-inflammatory, analgesic, hypoglycemic, and antidiarrheal activities. No studies have specifically assessed the ability of leaf extracts to inhibit urogenital infections although Bixa products have been used in folkloric medicine to treat gonorrhea and other infections. Few human studies have been conducted and published using Bixa leaf preparations. Many more studies have been conducted and published involving Bixa seed (annatto) extracts than with leaf extracts. No subchronic safety (toxicity) studies have been conducted in animals. A 6 month study in humans given 750 mg of leaf powder per day demonstrated no significant or serious adverse effects. Bixa leaf extracts appear to be safe when given under current conditions of use. However, additional human and animal controlled safety and efficacy studies are needed. In addition, detailed chemical analyses are required to establish structure-function relationships.