The Paradox of Milk and Bone Health

I grew up eating breakfast the way many of you probably did. On school days, I had a big bowl of cereal before going outside to wait for the bus. Nowadays, cereal has taken a hit. It’s common to talk about avoiding sugary, empty-carb laden foods like breakfast cereal. We are told whole grain cereals with little sugar added are a much healthier choice. But what about cereal’s best friend—milk?

Wherever you look milk is touted as an energy packed, nutrient rich food. I remember learning the food pyramid as a kid and learning that dairy was part of a healthy, balanced diet. Kids need milk to grow, and for strong bones and teeth, right? I mean, milk is served as the beverage of choice in our nations school system. As a student, I remember happily drinking my carton of milk at every lunch. Did I grow up to be so tall and healthy because I drank my milk?

Let’s take a deeper look into the issue and see if the facts line up. After all, milk is an $83 billion dollar industry in the United States alone. Worldwide, the annual revenue generated from dairy is $440 billion[1]. When you leave out the marketing, is there more to the picture than meets the eye? The truth may be murkier than you realize.

Milk for Strong Bones?

Have you ever heard of osteoporosis? That’s the medical term for porous bones[2]. Basically it means the bones have lost density, become more fragile, and are more likely to fracture. Osteoporosis is a huge problem, especially in the western world. In fact, about half of the world’s women will fracture a bone at some point in their lives[3].

While you may think of your bones as parts of a dry, hard skeleton, they are actually living and growing tissue. In fact, your bone is constantly being both formed and reabsorbed by your body. Osteoporosis occurs when your body begins to absorb more bone than it creates[4]. Calcium deficiency for extended periods of time is the biggest risk factor. Over time, low calcium intake is associated with “low bone mass, rapid bone loss, and high fracture rates[5]”. In order to prevent osteoporosis, women are encouraged to consume a high amount of calcium in their diet.

So what does this have to do with milk? Well, first off milk contains a lot of calcium. This is a well-known fact and the milk industry has promoted calcium supplementation as the single best reason to drink milk. Their argument is simple and goes something like this:

  • Milk contains a large amount of calcium.
  • Calcium is needed for strong bones.
  • Thus, milk consumption strengthens our bones. Drink milk!

Upon first glance, the argument looks rock solid. However, when the evidence is examined, the facts tell quite a different story.

The Weight of the Evidence

When gauging osteoporosis, the spine and hips are often measured because these bones carry a large portion of a person’s weight. Thus, when these bones fracture, it is usually a sign of osteoporosis. According to the above argument, women drinking milk should logically have stronger bones and fewer hip fractures.

However, when we look at the rates of hip fracture in postmenopausal women, we find that hip fractures are the most prevalent among groups of women who consume the most dairy products. These populations include northern Europe, the USA, Canada and Australia. In contrast, people from rural Asia and Africa tend to have the lowest rates of osteoporosis. These people generally eat little or no dairy products and have lower overall calcium intake[6].

Consider this table[7]:

Dairy countries Hip fracture rate per 100,000 Animal protein (g/day) Calcium intake (mg/day)
New Zealand 119.0 77.8 1217
Norway ≈200 66.6 1087
United States 144.9 72.0 973

 

Non-dairy countries Hip fracture rate per 100,000 Animal protein (g/day) Calcium intake (mg/day)
Papua New Guinea 3.1 16.4 448
Singapore 21.6 24.7 389
South African blacks 6.3 10.4 196

 

What’s wrong with this picture? If you accept the dairy industry’s marketing, countries that consume the most dairy should have the lowest rates of osteoporosis and hip fractures. However, the opposite is true. It seems that high calcium intake from dairy does not benefit or strengthen bones.

Why is this? The problem with milk is its protein. Diets high in animal protein (whether from milk or from meat) promote bone loss[8]. This happens because, “Animal protein leaches calcium from the bones, leading to its excretion in the urine[9]”. So even if you take in a huge amount of calcium from milk, the protein in milk (casein) causes you to lose more than you absorb. This is why women in countries with low animal protein consumption have fewer fractures, even though their calcium intake is relatively low. They are able to retain and utilize the calcium they did get.

The Simple Solution

So where did these women get their calcium? The answer is surprisingly simple: from plants. Take a moment and look at nature. Where do cows get their calcium? Their milk is calcium rich, so they obviously get loads of it in their diet. It comes from the plants they eat. Think about it, humans are the only mammals who continue to consume milk after they are weaned, (and we are the only ones who drink the milk of another species). All other animals get their calcium without drinking milk.

So focus on getting your calcium from plants. Great sources of calcium include dark-green leafy vegetables (kale, broccoli, collard greens, etc.), cereals, figs, raisins, nuts, legumes (beans, peas, lentils), tofu, and blackstrap molasses. Besides calcium, these foods are full of other nutrients without the fat, cholesterol, antibiotics and hormones present in milk.

If you’re left wondering how you can eat your cereal in the morning, rest assured there are plenty of good substitutes available. Many different ‘milks’ exist. Their sources range from soy to rice and from almonds to coconut. Over the last decade, the taste, quality, and availability of these products has greatly improved. Give it a try! You—and your bones—will be glad you did.

 

References:

[1] “Dairy Products Manufacturing Industry Profile.” First Research, 2012. http://www.firstresearch.com/Industry-Research/Dairy-Products-Manufacturing.html.

[2] IQ Solutions, Inc. “Osteoporosis Overview”, January 2012. http://www.niams.nih.gov/health_info/bone/osteoporosis/overview.asp.

[3] Ibid.

[4] “Osteoporosis – Overview – PubMed Health”, June 16, 2012. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001400/.

[5] IQ Solutions, Inc. “Osteoporosis Overview”, January 2012. http://www.niams.nih.gov/health_info/bone/osteoporosis/overview.asp.

[6] Abelow, B. “Cross-cultural Association Between Dietary Animal Protein and Hip Fracture: a Hypothesis.” Calcific Tissue Int, no. 50:14–8 (1992).

[7] Ibid.

[8] Campbell, Wayne W., and Minghua Tang. “Protein Intake, Weight Loss, and Bone Mineral Density in Postmenopausal Women.” The Journals of Gerontology Series A: Biological Sciences and Medical Sciences (July 6, 2010). http://biomedgerontology.oxfordjournals.org/content/early/2010/07/05/gerona.glq083.

[9] “Understanding Lactose Intolerance”. Physicians Committee for Responsible Medicine.

 

Jonathan Ewald
Jonathan Ewald

“If man thinks about his physical or moral state he usually discovers that he is ill.” – Johann Wolfgang von Goethe

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