milk

Milk is a white, nutrient-rich secretion produced by the mammary glands of mammals to feed young. The most widely consumed milk worldwide is cow’s milk, but milk from goats, sheep, buffalo, camels, and other species is also used for drinking and in dairy products. Dairy milk is commonly processed for human consumption and as a base for products such as cheese, yogurt, butter, and milk powders.

Milk consists mainly of water, with lactose as the primary carbohydrate, fat in the form of a cream, and protein mainly in the form of casein and whey proteins. It also contains minerals such as calcium and potassium, and vitamins such as A and D (often added as fortification). Composition varies by species, breed, feed, and processing; for example, whole cow’s milk typically contains about 3.5% fat and 3.3 g of protein per 100 ml, with roughly 4.8 g of lactose per 100 ml.

In production, milk is usually pasteurized to reduce pathogenic microbes and then homogenized to prevent cream separation. It may be standardized to different fat contents and fortified with vitamins and minerals. Shelf-stable forms, such as ultra-high-temperature milk, are also available.

Nutrition and health considerations include its role as a source of protein, calcium, and fat, as well as lactose intolerance in some individuals and milk allergies in a minority of people. Alternatives such as plant-based milks (soy, almond, oat) are common, often fortified but nutritionally distinct from dairy milk.

Economically, milk is a major agricultural commodity in many regions, with environmental and animal-welfare considerations shaping production practices and policy.