What's the Story? The Role of Milk in Your Diet

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What Is Milk?

Milk* is a nutritious food. It is an excellent source of calcium, phosphorus, riboflavin, and vitamin D and a good source of protein, vitamin A, potassium, and several B vitamins. Milk and foods made from milk (yogurt and cheese) make up one of the five basic food groups included in the U.S. government's Food Guide Pyramid. The Pyramid calls for two to three servings from this group daily.

What Are the Benefits of Milk?

Although milk provides many nutrients, it's especially important as a source of calcium and vitamin D.

All foods in the "milk, yogurt and cheese" food group are rich in calcium. So if you include enough foods from this group in your daily diet, you are assured of getting a reliable source of calcium every day. In the other food groups, however, only a few of the many possible choices are high in calcium. For example, only a few vegetables (such as spinach, collard greens, and broccoli) are calcium-rich; most other vegetables (including such favorites as potatoes, tomatoes, lettuce, corn, and carrots) are not. In addition, the calcium in dairy products is better absorbed from the digestive tract than the calcium from some other sources.

What Are the Charges Leveled against Milk?

Some extremist groups have claimed that milk is not a good food for infants and children. They also contend that milk should not be included in official dietary guidelines because of the high prevalence of lactose intolerance among U.S. minority groups. In addition, they claim that milk can cause or contribute to a wide variety of health problems including heart disease, diabetes, prostate cancer, allergies, and infant colic and that hormones in milk are causing early puberty in girls.

What Are the Facts?

Suitability for Infants and Children. The milk that you buy in the grocery store is not suitable for infants. During the first year of life, it is best for infants to drink human milk (that is, to be breastfed). The only acceptable alternative to human milk is infant formula. The most commonly used formulas are based on cows' milk proteins, but the milk is extensively modified to support the nutritional needs of infants. Unmodified cows' milk is not appropriate for infants during their first year because the amounts and proportions of nutrients that it contains are very different from the amounts present in human milk or infant formula.

For children over the age of one year, cows' milk is an excellent food. Of course, like all other foods, milk doesn't provide all the nutrients that a child needs. For good nutrition, children need foods from each of the major food groups (grains, vegetables, fruits, milk, and meat/meat alternatives). Milk should be only one component of a balanced diet.

Minority Groups and Lactose Intolerance. It is true that lactose maldigestion (the loss of the ability to produce the enzyme that digests the milk sugar lactose after early childhood) is more common among people of African, Asian, Native American, or Mediterranean heritage than among those of northern or western European origin. However, people with lactose maldigestion do not necessarily experience symptoms of intolerance after consuming usual amounts of milk (i.e., 8 oz.) Therefore, it is usually not necessary for these individuals to eliminate all dairy products from their diets. Many people with lactose intolerance can drink as much as two cups of milk daily with meals (one in the morning and one in the evening) without developing any gastrointestinal discomfort. Those who cannot tolerate regular milk can usually tolerate lactose-reduced milk, which is readily available in supermarkets. Most cheeses (except for cottage cheese and similar fresh cheeses) are also well tolerated because they contain no significant amount of lactose. Many lactose intolerant people also find that they have no difficulty tolerating yogurt. People with lactose intolerance need not eliminate dairy products from their diets; they simply need to choose dairy products wisely and find the amount that they can consume without developing symptoms.

Heart Disease. It is sometimes claimed that milk is bad for the heart because it is high in saturated fat. However, you do not have to eliminate milk from your diet in order to reduce your saturated fat intake. Instead, choose fat-free or reduced-fat milk and dairy products. Fat-free and reduced-fat milks provide as much protein, calcium, and vitamins as whole milk does, but with much or all of the fat removed.

Including low-fat dairy foods in your daily diet may actually reduce your risk of heart disease by helping to keep your blood pressure under control. High blood pressure is an important risk factor for heart attacks and strokes. Dairy products contain calcium, potassium, and magnesium all of which may help to prevent or reduce high blood pressure. An important study called DASH (for Dietary Approaches to Stop Hypertension) showed that a diet rich in fruits, vegetables, and low-fat dairy foods (3 servings a day) can help bring blood pressure down.

Diabetes. Some scientific reports have suggested a possible link between early exposure to cows' milk proteins and the risk of one type of diabetes in genetically susceptible individuals. Other studies have not supported this association, however. A recent review of the scientific data by the Juvenile Diabetes Foundation International concluded that there is no compelling evidence at this time that supports the claim that consuming cows' milk increases the risk of diabetes. The best advice for parents is to follow the American Academy of Pediatrics' recommendations for infant feeding: breastfeed your infant if possible, and don't feed unmodified cows' milk during the first year of life.

Prostate Cancer. Several scientific studies have indicated that men who consume large amounts of dairy products or calcium may have a slightly higher risk of prostate cancer than those who do not. Not all studies have shown this, however, and scientists are not certain whether this is a true cause-and-effect relationship.

Even if future research shows that the link between milk and prostate cancer is real, it is not likely that experts will ever advise men to stop drinking milk. Ample intakes of milk and calcium have been associated with lower risks of several diseases common among men, including colon cancer and hypertension. Men also need calcium to help keep their bones healthy just as women do. The best advice for men is to include milk or other dairy products in their diets in the moderate amounts called for by the Food Guide Pyramid 2 to 3 servings per day.

Allergies. True allergies to milk are uncommon, and they primarily affect infants and young children rather than adults. It has been estimated that between 2 and 5% of infants are allergic to the proteins in cows' milk. Infants with true milk allergies should not be fed formulas made from cows' milk. Fortunately, though, they may not need to avoid milk for a lifetime. Most children outgrow milk allergies as they get older.

Colic. The cause and effective treatment of infantile colic remains unclear and most infants are symptom-free by 4 to 5 months of age. According to the American Academy of Pediatrics, some infants may experience colic as the only symptom of food protein allergy. However, cows' milk allergy is unlikely to be an important cause of colic. Most infants with colic do not respond to a hypoallergenic formula. If your baby is extremely colicky, consult your baby's health care provider to see whether changing the formula or the mother's diet is worth a try.

Early Puberty in Girls. Experts aren't sure whether girls really are entering puberty earlier. If they are, the most likely explanation is that today's girls are heavier than their mothers were at the same age. Puberty tends to occur earlier in heavier girls.

There is no research demonstrating that milk or dairy products play a role in early puberty. Milk has always contained hormones in very small amounts; their presence is not a result of any changes in animal husbandry practices. Today's girls drink less milk than their mothers did. Thus, it seems very unlikely that milk is responsible for any change in the age at which girls enter puberty.

The Bottom Line

Except in cases of milk allergy (an uncommon problem), cows' milk and its products are acceptable, nutritious foods for persons one year of age and older. Milk and dairy products are good sources of many nutrients, and they are the best food source of the mineral calcium, a nutrient often not plentiful enough in the American diet.

Most of the health concerns that have been raised about cows' milk appear to be based on misconceptions or incomplete understanding of the facts. There is one important, scientifically justified health concern about milk, however the fact that many children and adolescents are not drinking enough of it. In the past few decades, children's milk consumption has gone down, while their consumption of other beverages has gone up. The Dietary Guidelines for Americans call for three servings of milk or other dairy foods daily for older children and adolescents (ages 9 and up), but young Americans in this age group are currently averaging only about two servings per day.

To make sure that the children in your family are drinking enough milk, it's a good idea to always serve milk as the mealtime beverage. Also, since children imitate adults, it helps for all family members not just the children to drink milk with their meals.

* All references to milk, unless otherwise designated, refer to cows' milk