What are fermented milk products?

Fermented milk products, also referred to as cultured milk products, are milk products that have been treated with bacterial cultures (usually lactic acid bacteria), yeast or mould. The purpose of the fermentation is to convert lactose (the naturally occurring milk sugar) to lactic acid. This causes gel formation, which thickens the milk, making it semi-solid. Examples of fermented milk products include yogurt, kefir, sour cream and crème fraîche.