New study affirms earlier evidence of tea’s beneficial effects on females’ bone density
by Craig Weatherby
Low bone mineral density (BMD) is considered a risk factor for hip fractures, which can cripple seniors, especially women, and even lead to death.
Estrogen helps build bones, which is why many post-menopausal women are diagnosed with osteopenia or osteoporosis.
- Aussie study links tea drinking (white, green or black) to denser hip bones in older women.
- Results affirm findings of 2000 British study.
- Research indicates that tea polyphenols fill the bone-boosting role of estrogen in post-menopausal women.
Osteopenia refers to bone mineral density (BMD) that is lower than normal but not low enough to be classified as osteoporosis (porous, weak bones).
Many women diagnosed with osteopenia are urged to take drugs that reduce bone loss—primarily bisphosphonates (e.g., Fosamax, risedronate), hormone replacement therapy, or raloxifene.
(The definition of osteopenia as a disease needing drug treatment has come under fire from expert physicians as producing little medical benefit while enriching pharmaceutical and scanning-device companies. See our July 2005, article “Diseased by Definition: Drug Profits Distort Medical Decisions.”)
Broadly healthful ways to increase bone density and strength include calcium and vitamin D supplements, walking, and resistance training (free weights or exercise machines).
And, studies indicate that high caffeine intake from coffee may be a risk factor for reduced BMD in women.
Like coffee, tea also contains caffeine, albeit only about half as much.
Why tea may bolster women's bones
The polyphenols found in white, green, and black tea may help maintain BMD in older women, who produce low levels of bone-boosting estrogen.
Population studies suggest that higher intakes of catechin-class polyphenols raises women's BMD: an effect that likely results from the antioxidants’ power to stimulate the cells that build bone (osteoblasts), which occurs potently in cell studies (Tokuda H et al 2007; Vali B et al 2007).
Green tea contains about 10 times more catechin polyphenols than black tea: some 30-40 percent of green tea solids, versus 3-10 percent of black tea solids.
The natural fermentation/oxidation process that turns green tea into black tea also converts catechins to antioxidants called theaflavins, which exert different effects and deliver their own distinct benefits.
British study indicated benefits of tea to bones
Seven years ago, researchers at Britain’s University of Cambridge decided to search for links between tea drinking and BMD in older English women, given the average Brit’s enthusiasm for their caffeinated “cuppa”.The Cambridge team knew that, unlike coffee, tea contains specific antioxidant compounds called catechins, which, based on animal and cell studies, appeared to hold the potential to increase bone mass.
They recruited 1,256 women aged 65-76, and measured the BMD of their lumbar spines and in various parts of their hips. The women reported their tea drinking habits and calcium intake.
Compared with non-tea drinkers, the BMD of tea drinkers was about five percent greater in the spine and in all but one of the hip areas tested. The findings held steady after the researchers adjusted for the women’s smoking status, use of hormone replacement therapy, coffee drinking, and whether milk was added to tea.
As they wrote, “Tea drinking may protect against osteoporosis in older women” (Hegarty VM et al 2000).
UK findings affirmed by Aussie study
A team of researchers at the University of Western Australia, led by Amanda Devine, Ph.D., conducted a similar study in 1,500 women, who were a bit older (70 to 85 years of age).
The Australian women were participating in a five-year study designed to detect any effects of calcium supplements on the risk of osteoporosis-related fractures (Devine A et al 2007).
A subgroup of 275 women filled out 24 hour diet-recall questionnaires, and all 1,500 women completed a questionnaire on beverage consumption at the end of the trial.
Dr. Devine and her co-workers measured the women's BMD during the fourth and fifth years of the study, and found that bone mineral density (BMD) was 2.8 percent higher in tea drinkers, compared to non-tea drinkers.
The Aussies found that, over the course of four years, tea drinkers among the women lost less bone mass in their hips. The tea drinkers lost an average of 1.6 percent of hip-bone density, while non-tea drinkers lost four percent.
There was no clear link between the average amount of tea a woman drank daily, and her bone density gains, but most of the tea drinkers reported quaffing three cups a day.
The tea-drinkers' BMD advantages seem highly significant, because very small differences in bone density can result in substantially greater risk of disabling hip fractures.
As Dr. Devine's group wrote, “Tea drinking is associated with preservation of hip structure in elderly women. This finding provides further evidence of the beneficial effects of tea consumption on the skeleton” (Devine A et al 2007).
- 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.
- Hegarty VM, May HM, Khaw KT. Tea drinking and bone mineral density in older women. Am J Clin Nutr. 2000 Apr;71(4):1003-7.
- Tokuda H, Takai S, Hanai Y, Matsushima-Nishiwaki R, Hosoi T, Harada A, Ohta T, Kozawa O. (-)-Epigallocatechin gallate suppresses endothelin-1-induced interleukin-6 synthesis in osteoblasts: inhibition of p44/p42 MAP kinase activation. FEBS Lett. 2007 Apr 3;581(7):1311-6. Epub 2007 Mar 1.
- Tokuda H, Takai S, Matsushima-Nishiwaki R, Akamatsu S, Hanai Y, Hosoi T, Harada A, Ohta T, Kozawa O. (--)-epigallocatechin gallate enhances prostaglandin F2alpha-induced VEGF synthesis via upregulating SAPK/JNK activation in osteoblasts. J Cell Biochem. 2007 Apr 1;100(5):1146-53.
- Vali B, Rao LG, El-Sohemy A. Epigallocatechin-3-gallate increases the formation of mineralized bone nodules by human osteoblast-like cells. J Nutr Biochem. 2007 May;18(5):341-7. Epub 2006 Sep 8.