In much of Westernized society, the concept that milk (cow’s milk) is necessary for strong bones is widespread. From early in life, children are encouraged to drink their milk by well-meaning parents who have been taught that milk is the ideal food from which to obtain calcium for growing and maintaining healthy bones and teeth. As a child grows into a teenager, he or she is further taught that milk is necessary if a young person wants to grow tall and excel in sports or any other activity of choice. Then, in adulthood, this person is encouraged to continue drinking milk to make sure of maintaining those strong bones, and, especially if that person is a female, she is told that she must drink milk in order to avoid getting osteoporosis later in life.
However, is all of this true? Is milk the miracle food for bones? In this article we will look at these issues, as well as take a much broader view of the subject of bone health.
“Got Milk?”
The National Milk Mustache “Got Milk?” campaign and website target young people, and the public in general, in an effort to convince them that milk is absolutely necessary for a healthy diet. Actors and sports stars are shown with milk mustaches along with their comments about how important milk is to them and their performance. Nutritional information is provided, particularly about calcium, and it is stated that three glasses of any kind of milk will give your body the calcium it needs. The website even states that milk is a better choice compared to soda pop, sports drinks, and many juices.(1)
However, since this campaign is “funded by America’s milk processors” and they believe that “America finds itself in a calcium crisis today because consumers aren’t drinking enough milk,”(1) it may be wise to look to some other potentially less biased sources of information that do not have something to gain through increased sales of milk.
Studies are mixed as to whether or not dairy supports bone health and will prevent osteoporosis. In one study which measured the BMD (bone mineral density) of 745 men and women more than 60 years old, higher dairy product consumption was associated with greater hip BMD in the men, but not in the women. However, calcium supplementation protected both men and women from bone loss in those whose dairy intake was low.(2) In a review of 57 studies of the effects of dairy foods on bone health, 53 percent were not significant, 42 percent were favorable, and 5 percent were unfavorable. Of 21 stronger-evidence studies, 57 percent were not significant, 29 percent were favorable, and 14 percent were unfavorable.(3)
The Big Picture
The status of bone health is not limited to how much dairy a person consumes. Generally, the underlying premise that increased milk consumption will strengthen bones is based upon the fact that bones contain a high percentage of calcium (the biggest reservoir of calcium in the body), and that the more calcium you consume the more likely your bones will be strong. And since milk contains fairly large amounts of calcium, all you need to do is to drink your milk, and your bones will be fine. However, this is a very narrow view of bone health.
There are a variety of other factors that influence bone health, and when these are taken into consideration, milk is no longer the miracle food for bones and, at best, is unessential and, at worse, a detriment to bone health. In addition to calcium, bone formation is also dependent upon vitamin D, vitamin C, vitamin K, and phosphorus. Other factors include increasing calcium absorption, minimizing calcium loss from the bones, minimizing calcium loss from the body, and promoting bone strength through other healthy means.(4)
Milk and dairy products are the best known sources of calcium, but they are not the only foods that contain good amounts of calcium. Other sources of calcium are green and leafy vegetables, such as broccoli, kale, mustard greens, and turnip greens, sesame seeds, almonds, soymilk, calcium-set tofu, and beans, such as pinto beans, black-eyed peas, and navy beans.
Many people think that just because they eat or drink a food with lots of calcium that all of the calcium ingested will contribute to strong bones. However, this is not the case. All sources of calcium have various calcium absorption percentage rates. For instance, the calcium absorption rate for milk is about 32 percent. That means that if you drink one cup of 2 percent milk with 297 mg. of calcium, only about 95 mg. of calcium is actually absorbed into your bloodstream for use in your bones. However, the absorption rate for many green vegetables is 50 percent or even more, as is the case with broccoli at almost 53 percent and mustard greens at almost 58 percent.(5) Along with these plant foods come cancer fighting phytochemicals and fiber; they are low in hypertensive sodium and artery clogging saturated fat, and have no heart disease promoting cholesterol. Milk does not have all of these benefits!
Another important consideration is that as calcium consumption increases, calcium absorption decreases. Thus, just throwing more calcium at your body does not automatically mean stronger bones. Reducing calcium loss from the bones and ultimately from the body is very important. Without minimizing calcium loss, merely consuming more calcium is like trying to fill a bucket with water that has a hole leaking out a similar amount of water to the amount being poured in.
A high intake of acid-forming foods, high intake of sodium, and low intake of potassium all contribute to calcium loss from the bones and the body. Acid-forming foods increase the acid load in the body, and the body responds by releasing calcium, which is alkaline and will neutralize the acid, from the bones. The foods that increase the acid load most significantly are all meats, fish, cheese, and eggs. These items are also low in calcium, so the resulting calcium balance is much lower, meaning that there is less calcium in the body than before these foods were eaten. Milk also increases the acid load, but since it also supplies calcium, the resulting negative calcium balance in the body is not so great. Some grains, particularly refined grains, are also acid-forming, but not as much as animal foods. However, fruits and vegetables positively affect the body’s calcium balance and minimize calcium losses. Thus, even though plant foods appear on nutritional charts to have less calcium per serving, the calcium that is consumed from them is much more effective in maintaining positive calcium levels in the body, and the net result is positive instead of negative. Again, milk is not able to out-perform plant foods for bone health.(6)
References:
1. MilkPEP (Milk Processor Education Program). Internet: http://www.whymilk.com (accessed February 20, 2005).
2. L. D. McCabe, B. R. Martin, G. P. McCabe, C. C. Johnston, C. M. Weaver, M. Peacock. “Dairy intakes affect bone density in the elderly.” American Journal of Clinical Nutrition. 2004 October; 80(4):1066–1074.
3. R. L. Weinsier, C. L. Krumdieck. “Dairy foods and bone health: examination of the evidence.” American Journal of Clinical Nutrition. 2001 March; 73(3):660–661.
4. Stephen Walsh. “Diet and bone health.” A Vegan Society briefing paper. January 2002. Internet: http://www.vegsource.com/articles/walsh_diet_bone.htm (accessed February 20, 2005).
5. Brie Turner-McGrievy. “Sources of calcium and calcium balance.” Vegetarian Nutrition. Internet: http://webct.ua.edu/SCRIPT/1554820051/scripts/serve_home (accessed February 20, 2005).
6. S. A. New. Nutrition New. Nutrition Society Medal lecture. “The role of the skeleton in acid-base homeostasis.” Proceedings of the Nutrition Society. 2002 May; 61(2):151–164.
To be continued . . .
Diane Herbert is a naturopath and lifestyle consultant. She received training from the NAD Lifestyle Consultant program, Thomas Edison State College, Clayton College of Natural Healing, and Bastyr University. Diane teaches health classes at the Gilead Institute located in Norcross, Georgia, gives health presentations, and contributes to the Institute’s literature and health flyer series. She may be contacted by e-mail at: gilead.net@usa.net.