One banana contains about 2 grams of protein, or 5 percent of the daily recommended intake. A banana also contains about 200 calories, 1 gram of fat and 2 milligrams of sodium.
Highest in carbohydrates, a banana contains 51 grams of carbohydrates, with 6 grams being from dietary fiber, 28 grams from sugar and 12 grams from starch. The highest vitamin content in a banana is vitamin B6, of which one banana contains 41 percent of the daily recommended value. Moreover, bananas are full of vitamin C, as one banana contains 33 percent of the recommended daily value. Bananas also contain small amounts of vitamin A, calcium, vitamin K, iron and several B vitamins.