Do high protein diets make your bones weaker?

The recent popularity of high protein diets, such as the Atkins or South Beach Diet, has led to fears about their effect on the strength of your bones.

The more protein in your diet, the more calcium you lose in your urine. The source of calcium was assumed to be from bone. However, a few studies suggest that people eating more protein have stronger bones.

High protein diets

One recent trial, published in the April 2004 edition of the Journal of Bone and Mineral Research, confirms that middle-aged people eating more protein have fewer hip fractures resulting from osteoporosis [1].

Almost 1,200 residents of Utah from 50-89 years of age who experienced hip fractures were compared with over 1,300 control subjects.

Higher protein intake was associated with a significant decrease in hip fracture among those under the age of 70 years.

Even a modest increase in protein from the group eating the least protein was associated with a 50% decrease in fracture rate. No effect was seen in people 70 or older.

In all groups, calcium from the diet was low. One-third of men and almost two-thirds of women used calcium supplements.

There is also research to show that even when eating half the recommended dietary intake of calcium — a practice common among American women — volunteers can eat more protein (20% versus 12% of total calories) mostly as meat, without having an adverse effect on calcium retention [5].

The high-meat diet consisted of 20% of daily calories as protein (about 117 grams) including 10.5 ounces of meat. The low-meat diet consisted of 12% protein, including 1.5 ounces of meat.

Meat contains substantial amounts of potassium and phosphorus, which reduce urinary calcium loss.

Most people think that calcium is the most important nutrient for bone health. Because of this, dairy foods (such as milk, yogurt or cheese) are usually recommended to women who want to protect against osteoporosis.

But contrary to popular belief, not all dairy foods promote bone health.

The high calcium content of processed cheese products, for instance, is offset by their high sodium and protein content, which can increase calcium loss. Cottage cheese is relatively low in calcium and potassium, and high in protein and sodium (both of which increase calcium loss) [2].

While calcium is essential for strong bones, it is not enough.

Muscles aren't the only things that get stronger when you train with weights. Bones get stronger too [3]. Think of bones as a growing organ. They respond to stress just as muscle does.

Unfortunately, many weight-training routines designed for women (light weights with high repetitions) simply don't impose enough stress on bone to stimulate remodeling.

Women, who have a greater risk of osteoporosis than men, need to meet the minimal essential strain required for bone remodeling to occur. Bone growth is proportional to the degree of stress imposed upon it. The greater the overload — within certain limits, of course — the greater the growth [4].

A suitable workout routine designed for women who want to get strong, lean, and fit while staying attractive and feminine is available elsewhere on this site.

The bottom line is that the link between the various nutrients in the diet and bone health is a very complex one. High protein diets themselves are not the problem. Many nutrients interact, not only among themselves, but with other genetic and environmental factors. More information on what to eat to protect your bones is available elsewhere on this site.

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References
1. Wengreen, H.J., Munger, R.G., Cutler, D.R., Corcoran, C.D., Zhang, J., & Sassano, N.E. (2004). Dietary protein intake and risk of osteoporotic hip fracture in elderly residents of Utah. Journal of Bone and Mineral Research, 19, 537-545
2. Weinsier, R.L., & Krumdieck, C.L. (2000). Dairy foods and bone health: examination of the evidence. American Journal of Clinical Nutrition, 72, 681-689
3. Umemura, Y., Sogo, N., & Honda, A. (2002). Effects of intervals between jumps or bouts on osteogenic response to loading. Journal of Applied Physiology, 93, 1345-1348
4. Cussler, E.C., Lohman, T.G., Going, S.B., Houtkooper, L.B., Metcalfe, L.L., Flint-Wagner, H.G., Harris, R.B., & Teixeira, P.J. (2003). Weight lifted in strength training predicts bone change in postmenopausal women. Medicine and Science in Sports and Exercise, 35, 10-17
5. Roughead, Z.K., Johnson, L.K., Lykken, G.I., & Hunt, J.R. (2003). Controlled high meat diets do not affect calcium retention or indices of bone status in healthy postmenopausal women. Journal of Nutrition, 133, 1020-1026