Which vitamin is most commonly fortified in milk?

Vitamin D is the vitamin most commonly fortified in milk because it plays a crucial role in calcium absorption and bone health. Many people, particularly those who have limited sun exposure, may not get enough vitamin D through natural sources. Fortifying milk with vitamin D helps prevent deficiencies and supports overall health, especially in populations that rely on milk as a significant dietary source of nutrition.

While vitamin A is also commonly added to milk, especially in reduced-fat and skim varieties, vitamin D has become standard in many places as a public health strategy to combat vitamin D deficiency. Vitamin B12 and vitamin C are less commonly added to milk specifically as a fortifying strategy.