Allium Species: A Remarkable Repertoire of Nutraceuticals with Anti-cancer Properties

Cancer - the name evokes fear and anxiety. Researchers are working tirelessly to bring hope to countless patients by developing prevention and treatment strategies. One approach is dietary modulation - which is documented to reduce the risk of cancer and increase the benefit of anti-cancer therapy. Allium species are a part of the daily diet in most parts of the world. Important members of this genus - chives, garlic, onions, and shallots add flavour and nutrition to food. These are prized for their organosulphur compounds and flavonoid content which are responsible for their diverse pharmacological activities. Traditional and scientific literature shows that dietary intake of Allium species prevents and aids the treatment of different cancers. In this review, based on an extensive search of available databases, the role of Allium species as nutraceuticals for cancer management was examined to ascertain the truth in the popular claims. Preclinical and clinical investigations show that consumption of the Allium members as a part of the diet and also the functional components (e.g., allicin, diallyl disulphide, diallyl trisulphide, ajoene, S-allyl cysteine, S-allyl mercaptocysteine, tuberoside M, onionin A, fisetin, quercetin, etc.) reduce risk of cancer and have significant antitumor activities. These act by varied mechanisms, including inhibition of gene expression, promotion of apoptosis of cancer cells, antiproliferative activity, and anti-oxidant and anti-inflammatory effects. It is emphasised that standardization of Allium products, their efficacy, dosage, safety profiles and interactions should be ascertained to corroborate their use. This article highlights the importance of Allium species for their prophylactic, therapeutic and immune-boosting ability in cancer management.