You probably know that calcium and vitamin D are needed to build strong bones. But what you may not know is that there are certain elements in your diet that can actually reduce bone density, increasing your risk for osteoporosis. 

Diet and Osteoporosis: Too Much Protein May Lower Bone Density
You need protein to build strong bones, but when you eat too much protein, your body produces chemicals called sulfates that can cause calcium to leach out of the bones. This effect on bones is more likely to occur with animal protein than vegetable protein. In the recent Nurses Health Study II, conducted by Harvard Medical School, 116,686 women were followed for 10 years. The researchers found that women who ate red meat at least five times a week were more likely to have a bone fracture than women who ate red meat only once a week. 

Diet and Osteoporosis: The Role of Caffeinated Drinks
In a recent study of 31,527 Swedish women ages 40 to 76, conducted by the Swedish Department of Toxicology’s National Food Administration, researchers found that women who drink 330 milligrams of caffeine or more a day — the equivalent of about four cups of coffee — have an increased risk of bone fractures. This risk was especially noted in women who had a lower consumption of calcium. The researchers did not find an association between tea consumption and an increased risk for bone fractures. One reason could be that the caffeine content of tea is typically half that of coffee. 

The recent Framingham Osteoporosis Study measured the bone mineral density in the spines and hips of 1,413 women and 1,125 men against the frequency of their soft drink consumption. The researchers concluded that cola and diet cola beverages (though not other carbonated drinks) may cause bone loss in women and may involve not just the caffeine, but the phosphorus in colas, too. “It may be that the connection between colas and bone loss is due in part to the substitution of soda for milk, decreasing calcium intake,” says Kristine Cuthrell, RD, research nutritionist and project coordinator, Cancer Research Center of Hawaii, University of Hawaii in Honolulu. 

Diet and Osteoporosis: The Retinol Form of Vitamin A
In the Nurses Health Study II, researchers found that women taking vitamin A in doses exceeding 3,000 micrograms (mcg) a day were twice as likely to suffer a hip fracture than women who take 1,500 mcg or less a day of vitamin A. Although vitamin A is necessary for bone growth, too much of the retinol form of vitamin A interferes with vitamin D absorption, which, in turn, causes bone loss. The retinol form of vitamin A can be found in such animal-source foods as liver, egg yolks, and dairy products as well as dietary supplements. The beta carotene form of vitamin A, found in plant sources such as carrots and sweet potatoes, has not been linked with a negative impact on bone health. 

Diet and Osteoporosis: Other Factors That May Raise Your Risk
Other dietary factors that can impact bone density include:
  • Sodium. Too much sodium in your diet can cause you to excrete calcium in your urine and perspiration. Sodium is found in table salt and many processed foods.
  • Oxalates, another form of salt found in some foods, can prevent you from absorbing calcium if the oxalates and calcium are contained in the same food product. Spinach, rhubarb, and sweet potatoes contain oxalates. Although these foods can play a role in a healthy diet, they should not be considered sources of calcium. Fortunately, oxalates do not interfere with the absorption of calcium from other foods eaten at the same time as the oxalate-containing foods.
  • Wheat bran. The only food known to reduce the absorption of calcium when eaten at the same time as calcium is 100 percent wheat bran. If you take calcium supplements, foods containing wheat bran should be eaten two or more hours before or after taking the supplement.
  • Alcohol. Excessive drinking of alcoholic beverages is also associated with lower bone density because alcohol interferes with the absorption of calcium and vitamin D. To lower your risk for osteoporosis, limit your intake of alcohol to one drink a day.
Diet and Osteoporosis: Rebalance With Fruits and Vegetables
“A diet low in fruits and vegetables and high in animal protein and carbohydrates, will tend to result in mild acidosis which, over time, can contribute to significant bone loss,” says Cuthrell. “Neutralizing an acid-producing diet, which can be done by eating fruits and vegetables, may be an important key to reducing bone loss while aging.” 

Eating a well-balanced diet can be tricky when you are trying to keep your bones healthy. However, getting the recommended amount of calcium each day to offset any loss of calcium caused by any other foods you eat will go along way to preventing bone loss.