Vegetarians are at a lower risk of developing osteoporosis. This is due to the high levels of vitamin K1 and many minerals found in plant foods. The increased consumption of the trace mineral boron also helps reduce their risk. Boron has been shown to have a positive effect on calcium and active estrogen levels in postmenopausal women, the group at highest risk for developing osteoporosis.
In one study, supplementing the diet of postmenopausal women with 3 mg of boron per day reduced urinary calcium excretion by 44 percent and dramatically increased the levels of 17-betaestradiol, the most biologically active estrogen. It appears that boron is required to activate certain hormones, including estrogen and vitamin D. Both estrogen and vitamin D are important for building and maintaining healthy bone structure.
Although boron has also been shown to be beneficial in arthritis, the mechanism of its action is not yet understood. It appears to play a role in calcium metabolism similar to that seen in osteoporosis prevention. No RDA is set for boron, and requirements vary from 1 to 6 mg per day, though most diets provide only 1 to 3 mg per day. Dried fruit, nuts, bananas, apples, and other fruits and vegetables are good sources of boron. Since nuts, fruits, and vegetables are the main dietary sources of boron, diets low in these foods may be deficient in boron.