The avocado is the fruit of the Persea Americana tree, which is native to the subtropical regions of the American continent. It has green, buttery flesh and a large central stone. Avocados are very high in both protein and oil. The avocado has the highest protein and oil content of any fruit. In fact, this soft-fleshed fruit can contain up to 30 percent fat. Don't let the high fat content put you off, though; avocados contain only monounsaturated fat, which may help to reduce the risk of cancer and heart disease.