Bananas have been the best-selling item at Walmart for several years.

While America's largest retailer doesn't disclose just how many bananas it sells, the number has to be immense considering that more than 200 million people shop in its stores worldwide every week.

We asked Wal-Mart spokeswoman Brooke Buchanan why bananas are perennially popular.

"Customers love bananas because they're an easy, healthy food to pack and eat and very affordable," Buchanan said. "Kids also love bananas, and so a lot of customers are probably thinking of their children."

Bananas are popular because they have "long been the cheapest food at the grocery store," Dan Koeppel wrote in his 2008 book "Banana: The Fate of the Fruit That Changed the World."

Koeppel also writes that Americans consume as many bananas as apples and oranges combined.