According to the U.S. Department of Health and Human Services (2013), nearly 30%

Question

According to the U.S. Department of Health and Human Services (2013), nearly 30% of females over the age of 65 have been diagnosed with osteoporosis leading to complicating fractures. Calcium and Vitamin D are vital components for osteoporosis prevention. Dairy products, especially milk, are common in the American diet and even have a specific familiar campaign, "Got Milk?" to help educate the public on the benefits of milk.

Most Americans have the perception that drinking milk will give us strong bones, but is this true? Are dairy products, specifically milk, an effective dietary source to help prevent osteoporosis or could they cause more harm than good? Should we as a society be drinking more or less milk? Are there better dietary choices for calcium or should we all be taking calcium supplements? Please elaborate on your reasoning with your research.

Explanation / Answer

Dairy foods provides a combination of four nutrients—calcium, phosphate, vitamin D and protein—present in the appropriate ratio that allows for the unique interaction favoring bone and skeletal muscle growth and development. This mixture of nutrients is like a gasoline mixture with just the right additives to get maximum performance – and winning mixture to lengthen and strengthen bones.

Girls’ bones grow and lengthen until about age 18, and boys stop around age 20. After that, the body focuses on strengthening and hardening bones, using dietary minerals like calcium and phosphorus to build bone until about age 30. This is known as peak bone density.

Building peak bone density is kind of like having a savings account. Up until age 30, you’re able to sock away all those minerals in your bones, building up your wealth (or health) for the future. That's why it is crucial that children, teenagers and young adults get enough bone-building nutrients. Drinking milk or eating dairy three times a day is the easiest way to build strong bones.

Milk is touted to build strong bones, but a compilation of all the best studies found no association between milk consumption and hip fracture risk; so, drinking milk as an adult might not help bones, but what about in adolescence? Harvard researchers decided to put it to the test.

Studies have shown that greater milk consumption during childhood and adolescence contributes to peak bone mass, and is therefore expected to help avoid osteoporosis and bone fractures in later life. But that’s not what researchers have found. Milk consumption during teenage years was not associated with a lower risk of hip fracture, and if anything, milk consumption was associated with a borderline increase in fracture risk in men.

It appears that the extra boost in total body bone mineral density from getting extra calcium is lost within a few years, even if you keep the calcium supplementation up. This suggests a partial explanation for the long-standing enigma that hip fracture rates are highest in populations with the greatest milk consumption. This may be an explanation for why they’re not lower, but why would they be higher?

This enigma irked a Swedish research team, puzzled because studies again and again had shown a tendency of a higher risk of fracture with a higher intake of milk. Well, there is a rare birth defect called galactosemia, where babies are born without the enzymes needed to detoxify the galactose found in milk; so, they end up with elevated levels of galactose in their blood, which can cause bone loss even as kids. So maybe, the Swedish researchers figured, even in normal people that can detoxify the stuff, it might not be good for the bones to be drinking it every day.

And galactose doesn’t just hurt the bones. Galactose is what scientists use to cause premature aging in lab animals—it can shorten their lifespan, cause oxidative stress, inflammation, and brain degeneration—just with the equivalent of like one to two glasses of milk’s worth of galactose a day. We’re not rats, though. But given the high amount of galactose in milk, recommendations to increase milk intake for prevention of fractures could be a conceivable contradiction. So, the researchers decided to put it to the test, looking at milk intake and mortality as well as fracture risk to test their theory.

A hundred thousand men and women were followed for up to 20 years. Researchers found that milk-drinking women had higher rates of death, more heart disease, and significantly more cancer for each glass of milk. Three glasses a day was associated with nearly twice the risk of premature death, and they had significantly more bone and hip fractures. More milk, more fractures.

Men in a separate study also had a higher rate of death with higher milk consumption, but at least they didn’t have higher fracture rates. So, the researchers found a dose dependent higher rate of both mortality and fracture in women, and a higher rate of mortality in men with milk intake, but the opposite for other dairy products like soured milk and yogurt, which would go along with the galactose theory, since bacteria can ferment away some of the lactose. To prove it though, we need a randomized controlled trial to examine the effect of milk intake on mortality and fractures.

Calcium is important. But milk isn’t the only, or even best, source.

It’s not a news flash that calcium is key for healthy bones. Getting enough calcium from childhood through adulthood helps build bones up and then helps slow the loss of bone as we age. It’s not clear, though, that we need as much calcium as is generally recommended, and it’s also not clear that dairy products are really the best source of calcium for most people.

While calcium and dairy can lower the risk of osteoporosis and colon cancer, high intake can increase the risk of prostate cancer and possibly ovarian cancer.

Plus, dairy products can be high in saturated fat as well as retinol (vitamin A), which at high levels can paradoxically weaken bones.

Good, non-dairy sources of calcium include collards, bok choy, fortified soy milk, baked beans, and supplements that contain both calcium and vitamin D (a better choice than taking calcium alone).

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