Worldwide, cow's milk, the protein of which mainly comprises casein, is most commonly used to make yogurt, but milk from water buffalo, goats, ewes, mares, camels, and yaks is also used in various parts of the world.
Dairy yogurt is produced using a culture of Lactobacillus delbrueckii subsp. bulgaricus andStreptococcus thermophilus bacteria. In addition, other lactobacilli and bifidobacteria are also sometimes added during or after culturing yogurt. Some countries require yogurt to contain a certain amount of colony-forming units of microorganisms.[2]
Yogurt is nutritionally rich in protein, calcium, riboflavin, vitamin B6 and vitamin B12.[30] It has nutritional benefits beyond those of milk. Lactose-intolerant individuals can sometimes tolerate yogurt better than other dairy products, because the lactose in the milk is converted to glucoseand galactose, and partially fermented to lactic acid, by the bacterial culture.[31]
Yogurt containing live cultures has been found effective in a randomized trial at preventingantibiotic-associated diarrhea.[32] Yogurt contains varying amounts of fat. There is non-fat (0% fat), low-fat (usually 2% fat) and plain or whole milk yogurt (4% fat).[33] A study published in theInternational Journal of Obesity (11 January 2005) also found that the consumption of low-fat yogurt can promote weight loss, relative to a gelatin placebo.[34]