Myths about milk and bone health

milk mythsDon’t get me wrong… I love butter, cream and delicious cheese as much as the next person.

But when I see some well-meaning folks tout dairy (usually low-fat… yuck) as some kind of necessity for bone health I can’t help raising an eyebrow.

So I set out to explore whether dairy really has any part to play.

It’s a good source of calcium, that we know.

But bone metabolism is complex and there’s a lot more than just calcium in there.

Other minerals, vitamins, hormones, dietary factors etc. also play a part and it doesn’t make evolutionary sense that we should need dairy because we didn’t eat dairy after weaning throughout evolution.

So… is dairy really good for your bones or is it just another myth?

A Quick Primer on Osteoporosis

The most common bone disease is osteoporosis, characterized by bone demineralization and deterioration of bone structure.

Osteoporosis = “porous” bones.

Healthy bones contain minerals and proteins tied together in an extremely rigid structure. In osteoporosus, these minerals and proteins deteriorate, the bones become less dense and therefore more likely to break.

Osteoporosis is most common in post-menopausal women and the resultant fractures can have a significant negative effect on quality of life.

The main reason why we would want to keep our bones dense and strong, is to prevent osteoporosis and resultant fractures later in life.

This is a pretty big problem in western countries and may perhaps be considered as one of many diseases of civilization as it is rare in hunter-gatherer populations.

It seems logical enough to associate dairy, the richest dietary source of Calcium, with bone mineral density given that calcium (in the form of calcium phosphate) is the most abundant mineral in bone.

Osteoporotic Bones

Of course, there’s more to dairy than just calcium.

Dairy is a whole food rich in animal protein, phosphorus, Vitamin K2 and various other nutrients that may or may not have an impact on our bones.

Controlled Trials on Dairy Consumption

Luckily for us, this issue has been investigated intensely and multiple randomized controlled trials have explored the effects of dairy consumption on bone mineral density.

In one study published in 1990, pre-menopausal women that added dairy to their diet had much lower rate of bone loss than a control group.

The control group lost 2,9% of bone mass from the vertebrae (bones of the spine) over a 3 year period, while the women who added dairy to their diet maintained their bone mass (1).

Another study published in 1997, this time in adolescent girls, discovered that the group of girls who drank additional milk had increased bone growth compared to a control group who didn’t (2).

Several other randomized trials that look at dairy consumption specifically show significant positive association with bone mineral content, which should lead to a reduced risk of fracture later in life (3, 4).

Basically, it seems that dairy products do in fact build stronger bones.

Despite the promising results of the controlled trials however, there are some observational studies, including the massive Nurses Health Study, that fail to show a positive effect for dairy and calcium consumption on fracture risk (5, 6).

(Of course, randomized controlled trials trump observational studies).

What About Calcium Supplements?

If you prefer to avoid dairy for one reason or another, there is the option to take a calcium supplement.

This has also been studied extensively, and calcium supplements on their own also lead to improved bone density and lower risk of fracture (7, 8).

However, I must warn against the use of calcium supplements because there is some evidence that taking calcium in the form of a supplement can increase risk of cardiovascular disease (9).

For further reading on calcium, dairy and bone health, read this excellent paper by Dr. Robert P. Heaney, one of the world’s leading experts on bone health.

Take Home Message

It turns out that the dairy and bone thing isn’t a myth after all. It has been extensively studied and there is no doubt about it that both calcium supplements and dairy lead to improved bone health.

I personally don’t take a calcium supplement, but I do eat a hefty amount of full-fat cheese at least several times per week. This brings my weekly calcium intake to appropriate levels.

If you’re female, then optimizing your calcium intake among other things, may be important to prevent bone loss and fractures later in life.

I should point out though, that this picture is more complicated than it seems.

For example, countries such as the U.S. which consume a lot of dairy also have a lot of osteoporosis.

And of course… dairy isn’t the only food that contains calcium. Leafy greens, nuts, some types of fish, eggs, etc. all contain a hefty amount.

What I recommend you do is eat a real food based diet that includes all the necessary vitamins and minerals, engage in weight bearing exercise (lift heavy things), optimize your Vitamin D status and generally make an effort to live a healthy lifestyle.

To sum up, yes… dairy appears to be good for your bones, but it is just one part of an extremely complex picture that involves various modifiable lifestyle factors that can impact future bone health.