Annatto is a rich source of tocotrienols, antioxidants that are similar in structure and function to vitamin E. The tocotrienols from annatto and other sources like palm oil and rice bran are the subject of current nutritional and medical research since these compounds are thought to prevent cancer due to their anti-angiogenic effect. The Annatto Seed, unlike palm oil or rice bran, does not contain any tocopherols so it is a natural source of pure tocotrienol compounds.
In developing countries, particularly in Colombia, people with low income and less access to modern medicine resources use folk medicine and natural remedies for the treatment of common infections. Achiote is also among those herbs used in Colombian folk medicine to treat infections of microbial origin. In addition to the known health benefits exerted by carotenoids, a bioactive sesquiterpene from achiote exhibited moderate anti-fungal activity. Norbixin isomers are responsible for the antimicrobial activity specific for Gram positive bacteria found in annatto extracts.
Annatto is safe for most people when used in food amounts; it can cause rare allergic reactions in those who are sensitive. Annatto has been linked to cases of food-related allergies, but it is not one of the “Big Eight” allergens (cow’s milk, egg, peanut, tree nuts, fish, shellfish, soy, and wheat), which are responsible for more than 90% of allergic food reactions. The Food and Drug Administration and experts at the Food Allergy Research and Resource Program (FARRP) at the University of Nebraska do not consider annatto a major food allergen.
Natural food colours such as annatto extract have not been extensively investigated as potential allergens. In one 1978 study of 61 patients suffering from chronic hives or angioedema, 56 patients were orally provoked by annatto extract during an elimination diet. A challenge was performed with a dose equivalent to the amount used in 25 grams (0.88 oz) of butter. Twenty-six percent of the patients reacted to this colour four hours after intake, worse than amaranth (9%) or synthetic dyes such as tartrazine (11%), Sunset Yellow FCF (17%), Food Red 17 (16%), Ponceau 4R (15%), erythrosine (12%) and Brilliant Blue FCF (14%).