Following the advice of experts, a growing number of health-conscious shoppers are eating mushrooms at least twice a week for the immune-supporting benefit of the vitamins they supply. Nutritionist Andrea Veinot not only urges shoppers to make sure their mushrooms carry enough of these nutrients, but also to confirm that the mushrooms are free of contaminants. Veinot adds that the latter is rarely a concern in Canada owing to federal inspection.

Cultivation, or indoor mushroom farming, now yields the overwhelming majority of the mushrooms found in grocery stores. Most of the button, cremini, and oyster mushrooms stacked on the shelves are grown this way. "If we did not have cultivation, we would not have so many mushrooms available," says Renata Cordova, who cooks them for her family three times a week. "Farmed mushrooms are more reasonably priced than wild ones and are on hand at the market every day."