An ancestor of the modern cow — the auroch — was first domesticated between eight- and ten thousand years ago in the Fertile Crescent. Though humans drink milk from many other mammals as well, cow milk has played an immensely important role in the human diet in many parts of the world ever since.
The ancient Sumerians, Egyptians, Indus Valley people, Europeans and Hebrews all used and loved cow milk. Today's humans, especially those living in the United States and Europe, have taken their love of cow milk to a whole new level. Slogans like "Got Milk?" and "Milk: It Does A Body Good" prove how much milk has been promoted in the West.
At about the same time, programs advertising the qualities of cow milk started appearing. A 1940s poster tells people that milk is great for "good teeth, vitality, endurance, strong bones". That's a truth nearly nobody would question today. But is milk really that healthy?
Milk: Why The Good Reputation?
Hear the word "milk" and you'll probably think about strong and healthy bones and teeth right away. Milk is, without doubt, one of the most readily available sources of calcium. It's no secret that calcium is key to healthy bones and strong teeth. Potassium and magnesium, which are also found in milk, are other important contributors to bone health and density.
By ensuring you have adequate levels of calcium, potassium and magnesium, you reduce your risk of heart disease, high blood pressure, stroke, kidney stones, and loss of muscle mass.
Because the calcium you consume is much more readily absorbed if you also have adequate vitamin D levels, milk is often fortified with this vitamin. The immune system also makes ample use of vitamin D. Choline, meanwhile, aids muscle movement, brain function, and sleep. The cancer-fighting vitamin B-12 that's so important for blood and nerve health is also present in milk, along with vitamin A, vitamin B-6, phosphorus, and riboflavin.
That sounds pretty impressive, right? When you read about all the good things in milk, you could almost possible to believe that cow milk provides a balanced diet all by itself! Do you want strong bones, healthy teeth, a reduced risk of cancer, an optimally-functioning cardiovascular system, and a smart brain? Milk sounds like the ideal answer, but one recent study questions this common wisdom.
Milk: The Other Side Of The Fairy Tale
Swedish researchers from Uppsala University took a very close look at the dietary habits of a staggering 61,400 women and 45,300 men in the 1980s and 1990s. The participants answered questions about how frequently they consumed foods considered to be dietary staples — including milk, yogurt and cheese — for a whole year. After that the study team monitored their health, noting how many developed fractures and how many died. Their results were published in the British Medical Journal in October 2014.
The women, who were examined earlier than the men, were then followed for a total of 20 years. The results were interesting, and not at all what one might expect. The heavy milk drinkers, those women who consumed 680 ml or at least three glasses a day, were found to be more likely to suffer fractures than those who drank less, including a 50 percent higher risk of hip fractures. While that's surprising, it is not the whole story.
The male study participants were followed for a shorter period, an average of 11 years. Again, those who drank more milk had a higher risk of dying and suffering fractures, but the differences between the milk drinkers and milk avoiders weren't as steep as with the women.
Professor Michaelsson concludes: "Our results may question the validity of recommendations to consume high amounts of milk to prevent fragility fractures. The results should, however, be interpreted cautiously given the observational design of our study."
Fermented Dairy Products Are Healthier?
Does this study make you question the health benefits of milk, which you may have believed in all your life? Before you start shunning dairy products altogether, you should know that the study also made another extremely interesting finding: fermented milk products like yogurt were not associated with higher risks of fractures and dying! In fact, consuming large amounts of fermented milk products was found to reduce these risks.
Professor Michaelsson and his team believe this difference to be due to the fact that milk contains a high amount of sugar (lactose and galactose), while fermented milk products don't. Animal studies show that these sugars play a role in the aging process. The study team reported: "A high intake of milk might, however, have undesirable effects, because milk is the main dietary source of D-galactose. Experimental evidence in several animal species indicates that chronic exposure to D-galactose is deleterious to health and the addition of D-galactose by injections or in the diet is an established animal model of aging."
At the same time, the team also made it very clear that further studies are needed and it's too early too conclude it's best to avoid a high-milk diet. Milk and milk products are, after all, the source of more than half of most people's calcium intake and a lack of calcium puts them at risk of osteoporosis and other diseases.