Milk, Calcium, and Bone Health
Even if you live under a rock, you know that in the US the current recommendation for most of the population is to enjoy 3 servings of dairy a day, including milk. One of the most well funded and persuasive ad campaigns of the three decades has been the Got Milk campaign led by the National Dairy Council. Parents are encouraged to provide milk for their kids’ growing bones and schools serve milk with every meal.
However, in recent years, a growing number of health experts and consumers are questioning milk and its purported health benefits. This tension has been captured by the Los Angeles Times in an interesting article on the pros and cons of drinking milk. The pros are well known: milk is nutrient rich, high in protein, and especially high in calcium, a nutrient lacking from the American diet. The cons reference a study that shows that heavy milk consumption may increase the risk of hip fractures and death in women.
The LA times article did not discuss the elephant in the room, though: If milk is so crucial to bone health (via calcium), how could it be that the countries with the highest rates of osteoporosis are those where milk consumption is also the highest? Conversely, how is it that countries with little to no dairy consumption have low rates of osteoporosis?
Research has shown that the ensuring bone health is much more complex than maximizing calcium intake. Calcium in a mineral that the body requires for bone and teeth health, and several other functions. 99% of the calcium in the body is stored in the bones and teeth. The remaining 1% is found in the bloodstream. Calcium can be added to the bones, but can also be leached from the bones, for example when the amount in the bloodstream in insufficient. In the first 30 years of life, bones mostly absorb calcium. After that, its mostly a maintenance task to keep the calcium from leaching.
Some scientists postulate that the current recommendations for 1000mg of calcium a day may be far greater than what the body actually needs. According to this theory, the bones are able to extract the calcium as needed from the bloodstream, no matter how little is consumed. As more calcium is entered into the bloodstream, a smaller percentage is utilized by the bones. The science around this is evolving.
Beyond consuming foods rich in calcium, what are some practical steps you can take to make sure your bones stay healthy and strong?
1. Weight bearing exercise builds muscles and bones. Walk, run, lift weights, and otherwise pound your bones. Even 1 minute of jumping jacks once a day can have a dramatic effect.
2. Avoid excessive intake of coffee, cola, alcohol, and sugars. Caffeine in quantities of 4 cups of coffee and higher per day can lead to calcium leaching from the bones.
3. Get adequate vitamin D (from sunshine or food). Vitamin D helps bones better absorb calcium.
4. Get adequate amounts of vitamin K from dark green leafy vegetables. Vitamin K helps to increase bone density and maintain bone health.
5. Protein intake should be in a reasonable range. Insufficient protein consumption will lead to muscle loss and strain on the bones. Too much protein can lead to calcium leaching from bones to neutralize acids in the bloodstream.
6. Keep in mind that while milk is calcium rich, there are non-dairy sources such as broccoli, spinach, soybeans, small fish, and white beans.
Dairy foods and bone health: examination of the evidence – Weinsier, Krumdieck – American Journal of Clinical Nutrition, 2000
Calcium and Milk: What’s Best for Your Bones and Health? – Harvard School of Public Health, 2015