Brai told the News Agency of Nigeria (NAN) in Lagos on Wednesday that such sliced onion if not properly stored when exposed could be highly poisonous as they could create toxic bacteria.
According to him, the vegetable contains sugar which promote bacteria growth.
“However, considering our environment and the perennial epileptic power supply, it is better to slice it when you want to make use of it.
“This is to avoid bacterial contamination which may cause adverse stomach infections and even food poisoning because of excess bile secretions,’’ Brai said.
The nutritionist, however, noted that onion contained compounds that had health benefits such as vitamin c, glutathione, flavonoids, allin and allicin.
He said these compounds possessed antioxidant properties which reduced blood cholesterol levels, hypertension and heart.
He said the compounds lowered risks of cardiovascular diseases and cancers of the gastrointestinal tract.
Brai added that vegetable belonged to the vegetable food group and it was almost certainly safe when eaten in amounts commonly found in our foods.
He said onion should be a key ingredient in every healthful vegetarian meal because of its versatile high beneficial sulfur compounds.
Brai said it belonged to the allium genus as garlic and was grown not only for use in cooking but for its antiseptic qualities.