Beginning in the early 20th century, the United Fruit Company promoted bananas in a series of pamphlets and ads, taking it from a little-known novelty to a household staple. At the heart of their campaign was an endorsement of the fruit’s healthy properties. In 1917 the United Fruit Company published “The Food Value of the Banana,” a collection of 15 opinion pieces touting the virtues of the banana as a nutritious snack. During the 1920s, the United Fruit Company hired doctors to extol the nutritional virtues of the fruit and recommend that babies should consume mashed bananas. The United Fruit Company’s test kitchens reported in 1924 that bananas with corn flakes and milk made the best breakfast for families. In 1939, they offered free textbooks—decidedly pro-banana—to schoolchildren.
See: “Extra, Extra, Get Your New Banana!” by Anne Garner on the New York Academy of Medicine Center for the History of Medicine and Public Health website