Researchers at the University of Tokyo have shown drinking green tea may significantly increase bone mineral density.

Their study, presented at the International Osteoporosis Foundation World Congress on Osteoporosis, Toronto, Canada, June 5, 2006, included 655 women aged 60 years or older. Participants completed a questionnaire about their consumption of green tea, milk, cheese, yogurt, fish, vegetable, tofu, natto (a soy food), meat and coffee; smoking, alcohol consumption, physical activity and use of anti-osteoporosis bisphosphonate drugs like Fosamax.

For each dietary item, subjects were divided into two groups: 1) those who consumed the item five or more days per week, and 2) those who consumed the item fewer than five days per week. The researchers then measured the bone mineral density (BMD) of the women's lumbar spines, as well as blood markers for osteoporosis risk, including levels of calcium, phosphorus, parathyroid hormone, alkaline phosphatase, osteocalcin, and vitamin D.

Women who drank green tea 5 or more days per week had an average BMD significantly higher (0.808 grams of hydroxyapatite-form calcium per square centimeter) than those drinking green tea less than 5 days per week (0.738 grams per square centimeter).

Green tea drinkers' bone-density advantage persisted even after results were adjusted for age, body mass index, other dietary items, smoking, alcohol, physical activity and use of osteoporosis drugs.

The Tokyo team hypothesized the catechin flavonoids in green tea provided the benefits via estrogenic effects known to build bone strength and/or induce apoptosis ("suicide") in bone-destroying cells called osteoclasts. Both mechanisms are similar to the ways in which bisphosphonate drugs like Fosamax prevent bone loss. But while these potent drugs can provoke inflammatory eye disorders, abdominal pain, nausea, vomiting, dyspepsia and diarrhea, green tea is not only completely safe, but a delicious beverage that offers a legion of other health benefits.