Ajobo, who is also Head of Department of Dietetics, told the News Agency of Nigeria (NAN) in Ibadan that onions were a good source of strong antioxidant and vitamin C that help to combat the formation of free radicals known to cause cancer.
He described onions as part of the alliums family of vegetables and herbs like chives, garlic, scallions and leeks.
“Allium vegetables have been cultivated for centuries for not only their characteristic, pungent flavours but also for their medicinal properties.
“Onions can vary in size, shape, colour and flavour and the most common types are red, yellow and white onions,’’ he said.
According to Ajobo, onion flavours can vary from sweet and juicy with a mild flavour to a sharp, spicy and pungent often depending on the season in which they are grown and consumed.
He also said that the possible health benefits of consuming onions (aside from lowering risk of several cancers) include improving mood and maintaining the health of skin and hair.
“Onions are a nutrient-dense food; meaning that while they are low in calories they are high in beneficial nutrients like vitamins, minerals and antioxidants.
“One cup of chopped onion contains approximately 64 calories, 15 grams of carbohydrates with no fat and no cholesterol.
“It also contains 3 grams of fibre, 7 grams of sugar, 2 grams of protein and 10 per cent or more of daily value for vitamin C, vitamin B-6 and manganese.
“Onions also contain a small amount of calcium, iron, folate, magnesium, phosphorus and potassium and the antioxidants quercetin and sulphur,’’ he said.
The dietician also recommended consumption of onions because of its many other health benefits.
“Allium vegetables have been studied extensively in relation to cancer, especially stomach and colorectal cancers.
“Their beneficial and preventive effects are likely due in part to their rich organosulfur compounds.
“Although the exact mechanism by which these compounds inhibit cancer is unknown, possible hypothesis include the inhibition of tumour growth and mutagenesis and prevention of free radicals.’’
According to Ajobo, several studies have proved that onion consumption help to lower risk of stomach cancer, colorectal cancer, colon and prostate cancer.
He, however, warned that consuming a diet of mostly onions has its health risks.
“It is best to eat a diet with a variety of foods than to concentrate on a single one; this is key to good health,’’ the dietician advised.