Yogurt, also spelled yoghurt, is a food produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as yogurt cultures. The fermentation of lactose by these bacteria produces lactic acid, which acts on milk protein to give yogurt its texture and characteristic tart flavor. It has many known health benefits. Yogurts are high in protein, calcium, vitamins, and live culture, or probiotics, which can enhance the gut microbiota. These can offer protection for bones and teeth and help prevent digestive problems. When topically applied to the skin, it is known to help moisturize, fight acne, prevent premature aging, relieve sunburn, and reduce discoloration. Also, yogurt can play a role as a gentle exfoliator since it contains lactic acid, an alpha hydroxy acid, that dissolves dead skin cells. This can help to create a natural glow as well as diminishing the appearance of fine lines.