Worrying About Milk
The August issue of Discover magazine had a story entitled "Worrying About Milk." One of the main focuses is on Dr. T. Colin Campbell, PhD, a prestigious nutritional biochemist at Cornell University, who also runs his own company Paracelsian.
Dr. Campbell grew up on a dairy farm and prided himself on the fact that he could drink a gallon or more of milk very day. Earlier in his scientific career he 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. According to the article, the bottom line for Dr. Campbell is simple: "It's unnatural to drink milk."
The following summarizes some of the interesting and important points of the article:
A majority of adults in Asia and Africa, along with many in southern Europe and Latin America, have trouble digesting lactose, the main sugar in the milk of both humans and cows. It is only people of Northern European decent that can predominantly tolerate lactose.
One theory is that 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 lactase, the enzyme that breaks down lactose, which is needed to digest human milk as well. But an apparent gene mutation inherited by people of northern European descent prevents the production of lactase from being turned down. As a result, the majority of Americans can drink milk all their lives.
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?" asks Dr. Campbell.
Dr. Campbell theorizes that cow's milk unnaturally stimulates enzymes and growth hormones in the human body that increase the risk of various diseases.
He has also come to the conclusion that cow's milk may not even do what it is supposed to do best - build strong bones, since recent studies suggest that humans may need less calcium for strong bones than was once believed. Additionally, other foods, including various vegetables and legumes, may be a better source than cow's milk.
In 1965, Dr. Campbell worked as coordinator of a US Aid project in the Phillipines, where poverty stricken children were dying mysteriously from liver cancer believed to be linked to malnutrition. However, to his surprise, Campbell discovered 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 US subsidized program. He was completely baffled until he read about a 1968 research study conducted in India and published in the Archives of Pathology (Arch Pathol 1968 Feb;85(2):133-7), which linked a milk protein to liver cancer in lab rats. "That was a signal event for me," Campbell says.
During the next three decades, Campbell conducted a series of experiments at Cornell University and Virginia Tech and found that rats given a brief initial exposure to aflatoxin, a carcinogen produced by mold growth, tended to develop liver cancer when fed casein, the main protein to milk. "We could turn on or turn off cancer growth," he says, by increasing or decreasing the amount of casein.
Dr. Campbell then initiated some research of his own by feeding casein to rats in normal doses, with 15 to 20 percent of their diet (by weight) coming from casein. The typical American diet is roughly 17 percent protein, says Campbell, though the protein, of course, is not all casein. He found that the threshold amount of casein required for switching on tumor growth averaged around 10 percent of the diet.
The Washington, DC-based Physicians Committee for Responsible Medicine (PCRM), is a non-profit advocacy organization, with over 100,000 members, that promotes preventive medicine through innovative programs, encourages higher standards for ethics and effectiveness in research, advocates broader access to medical services, and is opposed to milk consumption.
"It would be hard to imagine a worse vehicle for delivering calcium to the human body," says Neal Barnard, head of PCRM.
PCRM says that US officials have turned a blind eye to the potential health risks of milk. In December 1999, they filed a lawsuit against the US Departments of Agriculture and Health and Human Services claiming the agencies unfairly promote industry special interests through official dietary guidelines. The USDA, PCRM argues, has an inherent conflict of interest: a dual mission to assist dairy farmers as well as to promote good nutrition.
USDA officials claim that current dietary guidelines focus on dairy products as the major source of calcium because they 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 USDA, "but we have to fashion healthful eating around current habits."
In Dr. Campbell's view, as with many others, such thinking is circular. The reason a lot of Americans follow a dairy-rich diet, is that they assume it's the healthy thing to do, because they trust the government to tell them the truth.
Dairy proponents insist that most people who think they are lactose intolerant can actually digest small amounts of milk-the trick is to train them. Indeed, pilot studies funded by the dairy industry have shown that when such children consume milk slowly, in sips throughout the day and with meals, they can often tolerate one or even two glasses daily.
Does milk consumption have any impact on cancer risk? There is some disturbing evidence that many are unaware of:
Epidemiological research suggests a correlation between milk consumption and at least two kinds of cancer prevalent in Europe and North America: breast and prostate.
In Asia, where many people drink no milk at all, breast cancer tends to be rare. In rural China, for example, among women aged 35 to 64, Campbell found that breast cancer deaths averaged 8.7 per 100,000, as opposed to 44 per 100,000 in the US, about a 5-fold difference.
A comparative study published in 1989 showed that in Europe, two areas with higher milk consumption-Scandinavia and the Netherlands, also had higher breast cancer rates.
Worldwide, men seem far more likely to die of prostate cancer in countries where dairy consumption is high than in countries where it is low. A study published in 1977 revealed that 10 men die of prostate cancer in Western Europe for every one who dies in Asia.
Recently, two large, lengthy studies in the US linked dairy consumption to prostate cancer. In the Physician's Health Study, researchers tracked 20,885 male doctors over 10 years. Those who consumed at least 2 ½ servings of dairy food per day were 30% more likely to develop prostate cancer than doctors who consumed less than half a serving.
A 1999 study of nearly 50,000 subjects, called the Health Professionals Follow-Up Study, found that men who consumed a total of more than 2,000 milligrams of calcium per day raised their risk of metastic prostate cancer more than 4-fold.
Edward Giovannucci, a Harvard professor and coauthor of both of the above-mentioned studies, sees reason for concern. He believes that calcium itself, at high levels of consumption, promotes prostate cancer by depleting protective levels of vitamin D. "For prostate" he says, "the data are generally constistent, and the high relative risk in the Health Professionals Study is quite worrisome", given the push for high calcium intakes in the US.
Disparities between calcium intake and bone health can be seen worldwide. The more calcium people consumed, the more susceptible they seemed to be to hip fractures. People in those countries that consume the highest levels of dairy foods (North American and northern European nations) take in two or three times more calcium yet break two or three times more bones than people with the lowest calcium intake (Asians and Africans). "Osteoporosis," Campbell notes, "is not yet fully explained."
The 12 year Harvard Nurses' Health Study involving 78,000 nurses found that nurses who drank the most milk-two or more glasses per day, had a slightly higher risk of arm fracture (5% increase) and significantly higher risk of hip fracture (45% increase).
Although milk's calcium and other nutrients do promote bone growth, says Campbell, other substances in dairy foods and other animal products-certain proteins and especially sodium-actually leach some calcium from bone.
Do people really need as much calcium as the US dietary guidelines state? Currently, these recommended daily intakes are:
Children 4-8: 800mg
Kids 9-18: 1,300mg
However, are these numbers based on sound science and apply to all? Most likely not. There is much evidence that arguing against this assertion:
The Harvard Nurses' Health Study reported in 1997 that, among 78,000 women followed for 12 years, those who got the most calcium from dairy products had approximately double the hip fracture rate, compared to women who got little or no calcium from dairy products. In other words, the more calcium in your diet, the higher your risk of breaking bones.
The July 2000 issue of Pediatrics similarly reports that, among girls 12 to 18, calcium intake had no effect on bone density, although exercise did help build strong bones (Pediatrics July 2000; 106: 40-44).
The US guidelines are high, even when measured against those of most other western countries. As an example, the British recommended calcium intake for kids ranges from 350mg to 1,000mg (versus 800mg to 1,300mg in the US) and for adults is 700mg (versus 1,000mg in the US).
In the US, one in two women and one in eight men over age 50 breaks a bone because of osteoporosis, despite the fact that calcium consumption is among the highest in the world.
Walter Willett, a professor at the Harvard School of Public Health and chairman of the nutrition department, says, "There is no evidence that we have a calcium emergency as the dairy industry would have us believe. We have one of the highest calcium intakes in the world."
The Institute of Medicine recently suggested that teenagers and adults over age 50 increase their calcium intake to 1,300 and 1,200 milligrams, respectively, a day. The World Health Organization recommends 500 milligrams for children and 800 milligrams for adults. This is a substantial difference.
"The studies of bone mineral density can be highly misleading," says Dr. Willett. "What is clear is that an increase in calcium intake causes a onetime small increase in density (about 2%). However, this does not continue to accrue and disappears when stopping the extra calcium." The question is whether sustaining this slight increase will protect against fractures, something that has not been demonstrated.
In general, the Chinese eat less than half the calcium recommended by the USDA and seem healthy. Among women over 50, the hip fracture rate appeared to be one fifth as high as in Western nations.
Do the Chinese absorb calcium more efficiently from vegetables than Westerners do from dairy foods? Or might the rural Chinese, with their hard labor outdoors, make up for low amounts of calcium in their diet with exercise-induced bone growth? The absorption issue is important, as different sources of any nutrient may be absorbed with widely differing efficiency rates.
Critics of the governments push for increased milk consumption cite several examples of unfair practices, which may be adversely affecting the health of its citizens:
Dairy producers enjoy price supports and government purchase of surplus production. They plow some of their profits into promotional industry groups that fund research studies, educate health professionals about milk, and provide free materials to schools suggesting that milk is vital to good nutrition, despite the lack of adequate scientific data.
In the National School Lunch Program, milk is the only beverage that must be offered to children. A section of the Physicians Committee lawsuit alleges that milk's unique status in school lunches amounts to racial discrimination. Studies suggest that 70 % of African Americans, 50% of Hispanics and 90% of Asians have trouble digesting lactose, while only 15% of Caucasians do.
The program that serves free meals to needy children won't reimburse schools for non-dairy alternative to milk unless the substitution is requested by a doctor.
USDA deputy undersecretary Eileen Kennedy notes that consumer preferences-not dairy promoters-shape federal nutrition policies. Americans get three quarters of their calcium from milk and other dairy products. Kennedy suggests that if the government removed dairy as a recommended food group, people would not fill the gap by eating more calcium-rich foods such as vegetables and legumes? Rather, she thinks that they would continue to follow current trends-shirking exercise that builds bone, consuming more foods such as sodas and junk food that actually leach calcium from bones-and they'd be worse off than ever with less milk.
Actually the consumption of milk has been slowly dropping off for decades, unfortunately being replaced with an even worse choice - soda.
Discover August, 2000; 44-51.
COMMENT: This is an excellent summary of some of the dangers and problems with drinking milk. It doesn't even mention some of the other problems with it, such as the use of growth hormones, pasteurization, homogenization, and the unhealthy condition of the cows.
PCRM is doing a great job with their pursuit of altering the current views on the benefits of dairy. However, I am definitely NOT in agreement on their opinion of the benefits of a vegan or vegetarian diet.
A WORD OF CAUTION
Any practices or advice given in this publication are not intended to replace the services of your physician, or to provide an alternative to professional medical treatment.