Johns Hopkins Health Alert
Rethinking the Role of Protein-Rich Diets in Osteoporosis Prevention
Controversial evidence has emerged that suggests a high-protein diet with lots of dairy and meat products might actually promote the loss of bone mineral density, which can lead to osteoporosis. Here’s a look at some of the issues.
Among the many nutrients that help to build your bones, calcium and protein are crucial to maintaining the cycle of bone resorption (break down) and formation that replaces worn bone with new, structurally sound bone. Protein makes up about one third of the mass of bones, and a diet that is deficient in either calcium or protein is associated with a loss of bone mass, leading to osteopenia and, eventually, osteoporosis and fractures.
But beyond ensuring the strength of the skeletal system, protein and calcium also play an important role in regulating the delicate balance of acids and bases in the blood. When the blood becomes even slightly too acidic, calcium -- which is alkaline -- leaches from bone to neutralize the acids in the blood, a process that can lead to a reduction in bone mineral density.
The problem is that the typical American diet is high protein -- rich in meat, poultry, fish, eggs and dairy. When your body metabolizes these foods, they are broken down into sulfuric and organic acids that raise the acidity of the blood (digestion of cereal grains like rice and wheat also produce acidic compounds). Over a lifetime, chronic high levels of these acids may cause excessive leaching of the calcium in bone.
Different points of view. In fact, some experts hypothesize that the acidic nature of the Western diet may be contributing to the relatively high rates of osteoporosis in the United States and other industrialized nations. Other experts disagree, saying that the body compensates for this protein-induced loss of calcium from the bone by increasing the absorption of dietary calcium in the intestines. According to this theory, a high-protein diet will not affect bone health as long as calcium intake is sufficient.
- Some researchers believe it's not the amount of acid-forming, high-protein foods in the Western diet that contributes to osteoporosis, but rather the lack of acid-neutralizing foods, specifically fruits and vegetables.
- Another school of thought argues that the type of protein consumed is important. Some studies suggest that protein from vegetable sources, including beans, peas, and other legumes, may promote bone health more than animal proteins.
Bottom line: Until the debate over the roles that protein and other dietary components is clarified, your best nutritional bet to maintain the health of your bones is to get the recommended 1,000 to 1,200 mg of calcium daily -- from milk or another calcium-rich source -- and to eat a balanced, varied diet.
For older adults, that means 6 ounces of cereals, breads, rice and pasta (at least half of which should be made from whole grains); 2.5 cups of vegetables; 1.5 cups of fruit; 3 cups of low-fat or fat-free milk, yogurt or other milk products; and 5 ounces of fish or lean meat or poultry. Your intake of vitamin D is important, too. Aim for 400 to 1,000 IU per day, depending on your age.
Posted in Osteoporosis on August 26, 2011
Medical Disclaimer: This information is not intended to substitute for the advice of a physician. Click here for additional information: Johns Hopkins Health Alerts Disclaimer
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