Green Tea

Green Tea Provides Bone Benefits Similar to Calcium or Exercise

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.

Australian researchers report that bone mineral density (BMD) is 2.8% greater in tea drinkers than non-drinkers. The study involved 1,500 women (age range from 70-85) in a 5-year prospective trial looking at the effects of calcium supplements on osteoporotic fracture. Not only was tea drinkers' total BMD 2.8% higher than non-tea drinkers, but over the course of 4 years, tea drinkers lost an average of 1.6% of their total hip BMD, while non-tea drinkers lost more than twice as much (4%).

The 4 primary polyphenols in tea (epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin) were identified as being responsible. Green tea contains between 30-40% of water-extractable polyphenols, while black tea contains between 3-10%. "A recent review suggests that flavonoids from green tea may be associated with increases in BMD via a potent stimulatory effect on osteoblast function," noted lead researcher Amanda Devine. (Osteoblasts are the cells responsible for producing new bone.) Am J Clin Nutr. 2007 Oct;86(4):1243-7.

Green Tea Prevents Osteoporosis and Periodontal diseases

Excessive bone loss is a characteristic feature not only of osteoporosis but of periodontal disease. Green tea supports healthy bones and teeth both by protecting osteoblasts (the cells responsible for building bone) from destruction by free radicals, and by inhibiting the formation of osteoclasts (the cells that break down bone).

Another benefit of green tea consumption for those with periodontal disease: green tea short circuits the damaging effects of the bacteria most responsible for gum disease, Porphyromonas gingivalis. P. gingivalis causes gum damage by producing toxic byproducts such as phenylacetic acid and by stimulating the activity and production of enzymes called metalloproteinases (MMPs), which destroy both the mineral and organic constituents that make up the matrix of our bones. Epigallocatechin-3-gallate (EGCG) inhibits P. gingivalis' production of both phenylacetic acid and MMPs.

Scientific References

Devine A, Hodgson JM, Dick IM, Prince RL. Tea drinking is associated with benefits on bone density in older women. Am J Clin Nutr. 2007 Oct;86(4):1243-7. PMID:17921409.