Scientists have found that certain vegetables, such as onions, can prevent bone wasting in both male and female laboratory rats used as models for the human disease.
Roman Muhlbauer and Feng Li, of the Bone Biology Group at the University of Bern in Switzerland, say in the journal Nature that bone metabolism can be altered by eating from a list of 14 vegetables commonly found in the human diet.
"We show that a variety of salads, herbs and cooked vegetables that are common in the human diet alter bone metabolism in rats," they say.
"If this also happens in humans, then including an appropriate amount of these vegetables in the daily diet could be an effective and inexpensive way to decrease the incidence of osteoporosis."
A mixture of onion and Italian parsley, and a mixture of lettuce, tomato, cucumber, rocket, onion, garlic, wild garlic, common parsley, Italian parsley and dill, significantly inhibited bone resorption, the scientists found. When scientists combined the two mixtures, the effects were even greater.
The bone mass of male rats fed one gram of dried onion each day rose by about 17 per cent. Bone thickness improved by about 15 per cent and bone density by about 13 per cent.
In female rats with their ovaries removed - an animal model of the human menopause where oestrogen levels fall - the typical 30 per cent bone resorption seen in such rats was inhibited by 25 per cent when the rats were fed onions.
"Onions, therefore, inhibit resorption not only in male rats, but also in females in which bone resorption is stimulated by oestrogen withdrawal," the scientists say.