Milk and dairy foods are incredibly nutrient-rich. Studies show that if no dairy is consumed, intakes of calcium, magnesium, potassium, iron, riboflavin and vitamins A and D drop substantially.1
There are other ways to get these nutrients, however, they are not as convenient nor bioavailable as milk. Research has shown that adequate intake for calcium cannot be met with dairy-free diets while meeting other nutrient recommendations2 and that although it is possible to meet calcium recommendations without dairy, calcium-replacement foods are not a nutritionally equivalent substitute.3 In addition, absorption of calcium is less efficient from plant sources. For example, to replace the calcium in 1 cup of milk, a person would need to consume 8 cups of spinach, 2.2 cups of broccoli or 9 servings of legumes4 - foods often thought to be good sources of calcium. While motivated consumers could consume this amount of food, it is not practical for most Americans.
Most milk alternatives (such as soy, rice and almond) are fortified with calcium, but absorption of calcium is less efficient from plant beverages.5 In addition, vitamin D, protein and potassium levels may or may not be similar to milk. Calorie levels also are higher for most of the plant-based alternative milk products for a given calcium intake level.1
Science is still uncovering how the multiple nutrients in whole foods like milk work together to improve health, but it is clear that milk and dairy foods have an irreplaceable package of nutrients that cannot be found in any other single food or beverage.
1Scientific Report of the 2015 Dietary Guidelines Advisory Committee. USDA, Feb 2015.
2Gao X et al. J Amer Diet Assoc 2006; 106(11):1759-65.
3Fulgoni VL et al. Nutr Res 2011; 31(10):759-65.
4Weaver CM and Heaney, RP. Chapter 9: Food Sources, Supplements and Bioavailability. In: Calcium in Human Health. Humana Press, 2006.
5Heaney RP et al. Am J Clin Nutr 2000; 71(5):-9.