Bioactive components of onion (Allium cepa L.) — a Review

Onion (Allium cepa L.) is the second most important garden crop in the world after tomatoes. It has great nutritive value thanks to the content of physiologically effective compounds which exert protective (chemoprotective) effect on human health. Experimental studies have shown that the consumption of onion reduces blood pressure, stimulate haematopoiesis, heals heart and blood vessels, helps in treatment of asthma, and protects against some types of cancer. Onion is a versatile and strong antioxidant that quenches free radicals in the human organism. It is a rich source of phenolic substances, especially quercetin and its glycosides, phenolic acids, sulphur compounds (allicin), vitamins, and minerals