by Dave SteeleOn July 1st, the Journal of the American Medical Association – Pediatrics published an editorial that might surprise you. The authors, Dr. David Ludwig and Dr. Walter Willett - both of whom are physicians and professors at the Harvard Medical School - strongly question the consumption of cows' milk, even by children.
Quoting their article, “Dairy milk evolved to promote the growth of grazing animals at high risk for predation when small. The consequences of lifetime human exposure to the growth factors in milk have not been well studied. Milk consumption increases serum concentrations of insulin-like growth factor 1, an anabolic hormone linked to prostate and other cancers. In addition, modern industrial methods maintain dairy cows in active milk production throughout successive pregnancies, resulting in a milk supply with high levels of reproductive hormones.”
They cite a large body of research to support their claims. Adequate calcium, they point out, is easily obtained from other sources. They note that dairy consumption is not protective against bone fractures and that it is strongly correlated with prostate cancer. As Drs. Ludwig and Willett say, we'd do much better getting our nutrients from diets that include green leafy vegetables, legumes, nuts, seeds, and adequate protein.
None of this is news. That this advice is appearing in one of the world's preeminent pediatrics journals highlights its importance.
Safeguarding personal health, of course, is not the only good reason to avoid dairy products.
Dairy cattle, like all cattle, are surprisingly heavy polluters.
Cows belch a lot of methane ¨C by most estimates 100 to 200 liters per day. Because methane is some 34 to 86 times more potent a greenhouse gas than carbon dioxide (depending mostly on whether one counts its effects over 100 or 20 years, respectively) , this adds up to a huge impact on the climate. In fact, when one does the arithmetic, this amounts to about the same global warming effect, per cow, as a car. 
Cows also produce a lot of manure. According to the BC Ministry of Agriculture and Food, better than 2 cubic feet of the stuff a day.  Besides polluting our waterways and sometimes our drinking water, this manure is responsible for enormous amounts of ammonia pollution. Indeed, the majority of all ammonia pollution comes from cows.  Much of this becomes nitrous oxide in the atmosphere, a gas which, at 300 times the effect of CO2, dwarfs even methane in its global warming potential molecule for molecule. 
There is also indirect pollution involved in dairy production. Most important among those is the effects of corn and soy production. The great majority of corn and soy in North America and elsewhere is grown to feed animals. This is incredibly inefficient all around and cows are just about as inefficient as inefficient can be. According to Vaclav Smil's careful analysis, some 95% of the protein taken in by cattle is lost to humans.  We get only 5% of what we fed them back. This is made all the worse since it requires enormous amounts of fertilizers and pesticides to produce all of that corn and soy. Much of the fertilizer runs off into water ways and creates dead zones in lakes and bays and even the Gulf of Mexico.
All in all, dairy, like other animal agriculture, is highly polluting and highly wasteful. The fact is that dairy, like beef, is among the worst polluters, animal per animal, on earth.
And then, there's the plight of the cattle themselves. Like humans, cows have to give birth in order to produce milk. So, the cows are artificially inseminated once each year. Nine months later, a calf is born. Almost always, 24 to 48 hours after that, the calf is taken away. This causes great emotional pain both for the mother and for her offspring. Former cattle rancher Helen Weston describes how the mothers react: “The cow is an exceptionally loving and gentle creature. She cries for days when her calf is taken from her. It is a pitiful sound, a pitiful sound.”
Female calves are usually allowed to live. She'll be raised to be another dairy cow. If the calf is male, however, he may well be quickly killed. Or he may be raised for beef. More likely, though, he'll be sent to a veal farm instead. At the veal farm, he'll probably be fed an iron-deficient gruel so that the meat will be pale. He'll likely be chained by the neck in a tiny stall – with no room to walk or even turn. At 16 weeks of age, he will be sent to slaughter. According to the Humane Society of the USA, the veal industry would not exist were it not for the 'surplus' (i. e., male) dairy calves.
Dairy cows are bred to produce unnatural amounts of milk. Annual milk production per cow has more than doubled since the 1940s. The cows routinely suffer calcium deficiencies and painful mastitis. And, while their natural lives would span some 25 years, they are sent to slaughter before their fifth birthday. They become hamburger and "processed" beef.
We don't need dairy. It does a great deal more harm than good. So, eat like the doctors from Harvard suggest. Adopt a high quality diet filled with beans and grains and leafy greens and nuts and seeds. Your body will be better off. The world will be better off. And fewer cows will suffer so.
David Steele is a recently retired Research Scientist in the faculty of medicine at UBC. He holds a Ph.D. in Genetics and Molecular Biology from Emory University, in Atlanta. Dave is also the current president of Earthsave Canada.