|
 Dr. Glaser |
As Dee Anna Glaser, M.D., vice chairman of the dermatology department at St. Louis University, sees it, "As physicians, I don't think we have put enough emphasis on the role of diet and exercise on the overall health of our patients. There is more to learn and more research to be done, but it is becoming clear that diet and exercise affects all of our organs."
Dr. Glaser's perspective is showing up increasingly in the literature. For instance, studies of green tea show that it is among the most promising of antioxidants. Green tea contains polyphenols, which have been shown to confer photoprotection. Most notable among these polyphenols are epigallocatechin-3-gallate (EGCG) and epicatechin-3-gallate (ECG), which demonstrated the potential to prevent UV-induced immunosuppression and erythema in a study by Elmets et all.1
GREEN TEA AND BONE HEALTH More recently, the connection between green tea polyphenols (GTP) and bone health has come under the microscope. In an initial study, Leslie Shen, M.D., and colleagues at Texas Tech University Health Sciences Center, Lubbock, Texas, found that GTP may play a bone-protective role.2 The study evaluated bioavailability, bone mass and safety of GTP in preventing bone loss in middle-aged rats who either still had their ovaries or had had them removed.Dr. Shen found that GTP supplementation resulted in increased urinary epigallocatechin and epicatechin concentrations, liver glutathione peroxidase activity and femur bone mineral density, and decreased urinary 8-hydroxy-2'-deoxyguanosine and urinary calcium levels, but had no effect on serum estradiol and blood chemistry levels. According to the researchers, this demonstrated the existence of a bone-protective role of GTP that may contribute to an increase of antioxidant capacity and/or a decrease of oxidative stress damage.
FOLLOW-UP STUDY In a follow-up study, these same researchers added exercise to the mix in an evaluation of the potential impact of green tea and t'ai chi on bone health.3 The aim of this 24-week, randomized, placebo-controlled intervention trial is to investigate the effects of GTP and t'ai chi on postmenopausal women with osteopenia.
According to Dr. Shen, "Evidence suggests the importance of oxidative stress in bone metabolism and bone loss, and that [green] tea consumption may be beneficial to osteoporosis due to its antioxidant capability. However, lack of objective data characterizing tea consumption has hindered the precise evaluation of the association between tea ingestion and bone mineral density in previous questionnaire-based epidemiological studies.
"On the other hand, although published studies suggest that t'ai chi (TC) exercise can benefit bone health and may reduce oxidative stress, all studies were conducted using a relatively healthy older population, instead of a high-risk one such as osteopenic postmenopausal women." Therefore, Dr. Shen explains, this study was designed to assess the relationship of GTP and t'ai chi on older women who have already begun to experience the effects of bone mass loss. The primary outcome measures are concentrations of bone biomarkers. The secondary outcome measure is a biomarker of oxidative stress DNA damage. Investigators evaluating the endpoints will be blinded to intervention allocation. Results are currently being evaluated.
"Although the two studies are different, with the most recent study looking at a combination of green tea and t'ai chi and the earlier study discussing the antioxidant capacity of green tea polyphenols, this data highlights the importance of a healthy lifestyle and the impact that is has on our whole body," Dr. Glaser says.
In a review article, Dr. Shen notes, "In general, tea and its bioactive components might decrease the risk of fracture by improving bone mineral density and supporting osteoblastic activities while suppressing osteoclastic activities."4 Reports like these, Dr. Glaser says, show that "It is becoming evident that a well-balanced diet and exercise may be important for all of our different organ systems — skin, brain, GI tract, bones, you name it."
REFERENCES
1. Elmets C, Singh D, Tubesing K, Matsui M, Katiyar S, Mukhtar H. Cutaneous photoprotection from ultraviolet injury by green tea polyphenols. J Am Acad Dermatol. 2001;44:425-432.
2. Shen CL, Wang P, Guerrieri J, Yeh JK, Wang JS. Protective effect of green tea polyphenols on bone loss in middle-aged female rats. Osteoporos Int. 2008 Jul;19(7):979-990. Epub 2007 Dec 15.
3. Shen CL, Chyu MC, Yeh JK, Felton CK, et al. Green tea polyphenols and Tai Chi for bone health: Designing a placebo-controlled randomized trial. BMC Musculoskeletal Disord. 2009;10:110.
4. Shen CL, Yeh JK, Cao JJ, Wang JS. Nutr Res. 2009 Jul;29(7):437-456.
