Its supposed to be a 'heat' producing fruit..but as ophelia says, packed with nutrients, The caustic urshiol like sap is usually an issue with raw mangoes (esp around the stem attachment), by the time the fruit is ripe the amount is pretty much negligible..all the same peel the fruit, as the skin may contain traces..

Mango are high in vitamin A and C, but are also rather high in sugar as well if they're ripe.

Stay away from them if you have an allergy to poison ivy or poison sumac though, they're similar enough to cause issues.