Dairy consumption is one of the dietary habits that really distinguishes vegans from other vegetarians. Some nutritionists continue to question the adequacy of dairy-free diets because cow’s milk has maintained a solid reputation as a dietary essential. Of course, it makes no sense to believe that any one food is crucial to the diet. You need calcium, protein, and riboflavin, but it doesn’t matter where you get them as long as you do get them. The bias in Western cultures in favor of cow’s milk is based more on habit, economics, and politics than on science. There is a clear ethical rationale for avoiding cow’s milk, and as long as calcium can be obtained elsewhere, there is no reason for dairy consumption. However, evidence shows that diets which contain little or no dairy products could have some health advantages as well. Admittedly, the health risks associated with dairy consumption are speculative at best, but when combined, they are worthy of some attention.

Cow’s Milk Intolerance

Cow’s milk intolerance represents an interesting piece of nutrition history. It involves a decreased ability to digest lactose, the sugar found in milk and some milk products. As people age, they become less efficient at manufacturing the enzyme lactase, which is necessary to digest this sugar. Nutrition anthropologists believe that as recently as ten thousand years ago, no adult humans could digest milk sugar. The enzyme lactase was present in babies so that they could digest their mother’s milk. Lactase production slowly decreased throughout childhood and into adulthood as a normal part of development. Approximately ten thousand years ago, a mutation occurred that allowed some adults—namely those living in northern Europe—to continue digesting milk throughout adult- hood. Today, many people of northern European descent around the world can digest milk their entire lives. Conversely, many people from other parts of the world—such as those indigenous to southern Europe, the Mideast, Asia, Africa, and the Americas—digest it less well. Symptoms of this intolerance to cow’s milk include nausea, gas, and diarrhea. Not surprisingly, cow’s milk consumption is lower in parts of the world where lactose intolerance is more com- mon. Lactose intolerance is not a problem perse. Symptoms are avoided when dairy consumption is limited or when people use specially treated milk in which the sugar is predigested. The story of lactose intolerance is an intriguing one since it suggests that cow’s milk is a less natural food than most people believe.


A 1991 study in Finland was among the first to suggest that, in certain groups of children, cow’s milk consumption in infancy—whether as regular cow’s milk or as infant formula made from cow’s milk—was associated with greater risk of diabetes later in life. These groups of children produced antibodies to cow’s milk protein. The antibodies destroyed cells in the body that produce the essential hormone insulin. Since then, other studies have confirmed this finding, showing that cow’s milk consumption throughout childhood could pose a risk in children who were genetically susceptible to this problem. Other studies, however, have not supported these findings.

Ovarian Cancer

One study at Harvard University found that women who consume dairy foods have a higher risk of ovarian cancer. Other studies have not supported this finding. If such a risk exists, it probably involves the sugar galactose, a component of the milk sugar lactose. Galactose itself undergoes breakdown and metabolism. However, some women lack the enzyme for proper metabolism of this sugar. In this case, high blood levels of unmetabolized galactose could possibly damage ovaries.


Although cow’s milk consumption does not directly influence iron status in most people, overconsumption of dairy foods can be a very real problem in young children. Particularly among toddlers and preschoolers, too much cow’s milk in the diet can make a child less hungry for iron-rich foods. Cow’s milk doesn’t contain iron, and if it displaces other foods, the result is a diet low in iron. In addition, cow’s milk can interfere with iron absorption from other foods. The net result is that children who drink too much cow’s milk run a risk of iron-deficiency anemia.

Heart Disease

The culprit here, once again, is cow’s milk sugar, galactose, which may attach to proteins in the walls of the arteries, promoting the buildup of plaque.


Colic is an uncomfortable digestive disorder experienced by infants. A sen- sitivity to cow’s milk protein may be one cause. In fact, even in breast-fed infants, colic can occur if cow’s milk protein from the mother’s diet is passed to the infant through her breast milk.

Vitamin D Toxicity

In the United States, law requires that cow’s milk be fortified with vitamin D; each quart must contain 10 micrograms. However, large volumes of cow’s milk are fortified simultaneously. As a result, if the milk isn’t properly mixed, some quarts on the grocery store shelves may contain virtually no vitamin D while others may have many times the federal requirement. This is cause for concern because vitamin D is toxic in amounts just five times greater than the requirements. In one survey, some samples of cow’s milk were found to contain five hundred times more vitamin D than the amount allowed by the federal government.


In certain people, high blood levels of the cow’s milk sugar galactose can lead to cataract development. This affects only people who have an impaired ability to metabolize galactose, although this relationship is still somewhat speculative.

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