T. Colin Campbell grew up on a small dairy farm of 210 acres, nestled among glorious green pastures near the Shenandoah Valley in northern Virginia. Almost from the moment he learned to walk, he dogged the footsteps of his father, Tom Campbell, as he tended the farm’s 20 to 30 milk cows. Eventually, young Colin was given the chore of “stripping” by hand any milk from the cows’ udders that the milking machine left behind. He also learned how to operate the family butter churn and, on special weekends, helped man the hand-crank bucket used to make ice cream. The Campbells were a simple family, without much money, but considered themselves blessed to have milk straight from the cow. “We had the nectar of life,” Campbell says. “I was proud of the fact that somehow, every day, I could drink a gallon of milk, or more.”

Campbell went on to become one of the world’s leading experts on nutrition. Two decades ago he contributed to the first federally funded report on the relationship of diet to cancer, an influential study that helped establish the nutritional importance of grains, fruits, and vegetables. At age 66, he is nearing retirement as a nutritional biochemist at Cornell University, in the heart of upstate New York’s dairy country. He lives on a quiet residential street near the campus, by all appearances like most of his neighbors. But these days not one drop of milk touches the lips of anyone in Campbell’s household and his refrigerator is stocked with soy cheeses, sorbet, and rice milk. “People might think we’re nuts,” he says. “But nondairy beverages and foods are pretty good once you adjust to the taste.”

Like most Americans, Campbell once assumed that dairy products were not only wholesome but also an essential part of the daily diet for anyone desiring good teeth and strong bones. After years of scientific research, however, he’s now convinced that cow’s milk is responsible for a share of our nation’s medical woes. The fact that fats in dairy products can contribute to hardening of the arteries and heart disease has long been common knowledge. But Campbell worries that stocking up on skim milk and low-fat yogurt—or going organic because of concerns about cows exposed to pesticides, antibiotics, and bovine growth hormones—may offer only limited protection against the potential health hazards of milk.


The bottom line for Campbell is simple: “It’s unnatural to drink milk.” In fact, the majority of people worldwide literally can’t stomach milk by the time they reach age 10. Most adults in Asia and Africa, along with many in southern Europe and Latin America, can’t digest lactose, the main sugar in the milk of both humans and cows. They suffer from bloating, cramps, or diarrhea if they try. It was only because of a genetic aberration that milk became a food staple in northern Europe and North America. Nature normally programs the young for weaning before they reach adulthood by turning down production in early childhood of the enzyme that breaks down lactose. But a gene mutation inherited by people of northern European descent prevents the production of this enzyme from being turned down. As a result, most Americans can drink milk all their lives.

The ultimate problem with cow’s milk, according to nutritional biochemist T. Colin Campbell, is that nature concocts different formulas of mother’s milk for different species. What’s good for baby calves isn’t necessarily good for human babies or adults

Campbell argues that the ultimate problem with cow’s milk is that nature concocts different formulas of mother’s milk for different species. What’s good for baby calves isn’t necessarily good for human babies or adults. “Isn’t it strange that we’re the only species that suckles from another species?” he says. Campbell theorizes that cow’s milk unnaturally stimulates enzymes and growth hormones in the human body that increase the risk of various diseases. Moreover, he has come to the conclusion that cow’s milk may not even do what it is supposed to do best—build strong bones. And recent studies suggest that humans may need less calcium for strong bones than was once believed and that other foods, including various vegetables and legumes, may be better sources than cow’s milk.

“It would be hard to imagine a worse vehicle for delivering calcium to the human body,” says Neal Barnard, head of the Washington, D.C.-based Physicians Committee for Responsible Medicine, a nonprofit advocacy organization that promotes vegetarianism and is opposed to milk consumption. Of the 100,000 or so members of the Physicians Committee, about 5,000 are actually physicians. Both Barnard and Campbell, a science adviser for the group, believe that government officials have turned a blind eye to the potential health risks of milk. Last December, the Physicians Committee filed a lawsuit against the U.S. Departments of Agriculture and Health and Human Services claiming the agencies work in concert with the dairy industry to promote milk products through official dietary guidelines. The USDA, the Physicians Committee argues, has an inherent conflict of interest: a dual mission to assist dairy farmers as well as to promote good nutrition. What if the subsidized dairy foods that the government recommends aren’t good choices for healthy eating?

Government health officials argue that evidence of health risks from milk is circumstantial. Moreover, they contend that dietary guidelines that focus on dairy products as a major source of calcium are based on a realistic assessment of the food choices most Americans make. “There’s nothing against vegetable sources of calcium,” says Eileen Kennedy, deputy undersecretary of research, education, and economics at the Department of Agriculture. “But we have to fashion healthful eating around current habits.”

In Campbell’s view, such thinking is circular. The reason a lot of Americans follow a dairy-rich diet, he argues, is that they assume it’s the healthy thing to do.

Gregory Miller, vice president of nutrition research at the National Dairy Council, dismisses the Physicians Committee as “essentially an animal rights organization. If consumers want nutritional advice,” he says, “they should get it from mainstream health and medical health professional organizations. . . . Here they are saying don’t eat the food group that provides 75 percent of calcium in the diet. With little kids who don’t like vegetable sources like broccoli and kale and brussels sprouts, it becomes especially important.”

Campbell, who believes all animal protein is bad for human health, says he is not an animal rights activist. He believes that animal experimentation is essential for research.

All through his undergraduate years at Penn State and then veterinary school at the University of Georgia, Campbell spent his time happily milking the family cows during summer vacations and drinking glass after glass of fresh whole milk. When he transferred to Cornell in 1956, after landing a full scholarship for doctoral studies in animal nutrition, he set out to learn how to produce more animal protein “so we could eat more of it.” But his outlook changed after he headed overseas in 1965 to serve for 10 years as coordinator of a U.S. AID project in the Philippines, where poverty-stricken children were dying mysteriously from liver cancer believed to be linked to malnutrition. For protein, the children depended largely on peanuts, which in the tropics often contain relatively high amounts of aflatoxin, a carcinogen produced by mold growth. To his surprise, Campbell discovered during his tenure in the Philippines that the incidence of liver cancer was especially high among some of the best nourished kids, whose diets were supplemented with powdered milk provided through a U.S.-subsidized program. He was completely baffled until he read about a 1968 research study conducted in India that linked a milk protein to liver cancer in lab rats. “That was a signal event for me,” Campbell says.

Left with the suspicion that feeding milk to the Filipino children may have been a mistake, Campbell began studies to explore the question. During the next three decades, he conducted a series of lab experiments at Cornell and Virginia Tech and found that rats given a brief initial exposure to aflatoxin tended to develop liver cancer when fed casein, the main protein in milk. “We could turn on or turn off cancer growth,” he says, by increasing or decreasing the amount of casein.

Still, a question remains: Are such animal studies relevant to humans? One theory widely accepted by cancer researchers is that tiny precancerous lesions accumulate throughout the body because of random mutations or exposure to small amounts of carcinogens. These lesions normally remain dormant, but a steady dose of cancer promoters in the diet may override natural defenses against the growth of tumors. In lab animals, the liver has become a litmus test for cancer studies because of its sensitivity to carcinogens and its rapid reproduction of cells. And among lab animals, rats are considered particularly relevant to human cancer studies because they need the same nutrients and proportion of protein for maximal growth as humans. But lab rats often don’t get cancer from suspected food carcinogens unless they are given enormous doses. Since humans normally receive far less exposure, it’s not clear if the tests always reveal a significant danger. Campbell chose to feed casein to rats in normal doses, with 15 to 20 percent of their diet (by weight) coming from protein. That proportion is typical in the American diet. He found that the threshold amount of casein required for switching on tumor growth averaged around 10 percent of the diet. According to these results, says Campbell, even two or three glasses of milk a day can pose a significant risk. “If that same evidence existed for some food additives,” he says, “there would be a public furor.”

E. J. Hawrylewicz, a nutritional biochemist and research director at Mercy Hospital and Medical Center in Chicago, performed a similar series of experiments that revealed lab rats are more likely to develop breast cancer tumors when fed casein than when fed soy protein. But he found that the lab rats’ diets had to be very rich in casein, at least 20 percent, to produce significantly more tumor growth, as opposed to Campbell’s results of 10 percent. Because Americans consume a variety of proteins to reach 20 percent—mostly from animal foods like eggs and meat in addition to dairy—Hawrylewicz argues that casein may not be harmful if consumed in modest amounts. Nonetheless, Hawrylewicz agrees with Campbell that a good anticancer strategy is to choose a diet rich in plant rather than animal proteins.

WHERE'S THE CALCUIM?

Although milk is commonly thought to be the premier source of calcium, many other foods are calcium-rich. Consider that a cup of cow’s milk contains about 300 milligrams of calcium. The following portions of foods each supply more than 250 milligrams of calcium: a cup of collard greens, a cup of turnips, an ounce of Swiss cheese, three ounces of sardines, or four ounces of flour. Not only do these—and foods like beans, tofu, and fish—contain calcium but evidence suggests they supply it in a form that is more fully absorbed by the body than milk-derived calcium. Thus a diet high in calcium-rich plant foods or other nonmilk alternatives may reduce the amount of calcium you need to take in to keep your bones healthy. In the United States, the suggested daily calcium intake is 800 milligrams for kids 4 to 8, 1,200 milligrams for kids 9 to 18, and 1,000 milligrams for adults. The World Health Organization, however, recommends 500 milligrams for children and 800 milligrams for adults.

 

But Miller, of the Dairy Council, contends that casein is a red herring. He and other nutritionists cite evidence for the health benefits of dairy products: Studies linking milk consumption to bone growth, reduced blood pressure, and reduced risk of colon cancer. And, he adds, “other milk proteins have demonstrated anti-carcinogenic properties.”

In cancer research, pinpointing a singular mechanism that triggers tumor growth is invariably an elusive quest. Each cell where cancer may develop passes through several precancerous stages; some may have mechanisms in common and yet have other pathways peculiar to one bodily organ—lymph nodes, say, or brain cells. “There are likely many, many mechanisms,” Campbell says. But epidemiological research adds a new line of evidence, and in this case it suggests a correlation between milk consumption and at least two kinds of cancer prevalent in Europe and North America: breast and prostate.