Long-Term Intake of Green Tea Extract Causes Mal-Conformation of Trabecular Bone Microarchitecture in Growing Rats.
The purpose of this study was to examine the effects of green tea extract (GTE) intake on bone structural and physiological properties, such as bone mass, trabecular bone microarchitecture, cortical bone geometry, and bone mechanical strength, in growing rats. Four-week-old male Wistar rats were divided into the following four eenoups: standard diet feeding for 85 days (S-CON) or 170 days (L-CON), and GTE diet feeding for 85 days (S-GTE) or 170 days (L-GTE). At the end of the experiment, in addition to measurement of circulating bone formation/resorption markers, bone mass, trabecular bone microarchitecture, and cortical bone geometry were analyzed in the left femur, and bone mechanical strength of the right femur was measured. There was no difference in all bone parameters between the S-CON and S-GTE groups. On the other hand, the L-GTE group showed the decrease in some trabecular bone mass/microarchitecture parameters and no change in cortical bone mass/geometry parameters compared with the L-CON group, and consequently the reduction in bone weight corrected by body weight. There was no difference in bone formation/resorption markers and bone mechanical strength between the S-CON and S-GTE groups and also between the L-CON and L-GTE groups. However, serum leptin levels were significantly lower in the L-GTE group than in the L-CON group. Thus, the long-term GTE intake had negative effects on bone, especially trabecular bone loss and microarchitecture mal-conformation, in growing rats.
Minematsu A, Nishii Y, Imagita H, Sakata S
Calcif. Tissue Int. Nov 2017
Green tea and bone metabolism.
Osteoporosis is a major health problem in both elderly women and men. Epidemiological evidence has shown an association between tea consumption and the prevention of age-related bone loss in elderly women and men. Ingestion of green tea and green tea bioactive compounds may be beneficial in mitigating bone loss of this population and decreasing their risk of osteoporotic fractures. This review describes the effect of green tea or its bioactive components on bone health, with an emphasis on (i) the prevalence and etiology of osteoporosis; (ii) the role of oxidative stress and antioxidants in osteoporosis; (iii) green tea composition and bioavailability; (iv) the effects of green tea and its active components on osteogenesis, osteoblastogenesis, and osteoclastogenesis from human epidemiological, animal, as well as cell culture studies; (v) possible mechanisms explaining the osteoprotective effects of green tea bioactive compounds; (vi) other bioactive components in tea that benefit bone health; and (vii) a summary and future direction of green tea and bone health research and the translational aspects. 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.
Shen CL, Yeh JK, Cao JJ, Wang JS
Nutr Res Jul 2009
Coffee, tea and caffeine consumption in relation to osteoporotic fracture risk in a cohort of Swedish women.
Consumption of coffee and tea, and total intake of caffeine has been claimed to be associated with osteoporotic fracture risk. However, results of earlier studies lack consistency.
We examined this relation in a cohort of 31,527 Swedish women aged 40-76 years at baseline in 1988. The consumption of coffee, caffeinated tea and the intake of caffeine were estimated from a self-administered food frequency questionnaire (FFQ). Multivariate-adjusted hazards ratios (HRs) of fractures with 95% confidence intervals (95% CIs) were estimated by Cox proportional hazards models.
During a mean follow-up of 10.3 years, we observed 3,279 cases with osteoporotic fractures. The highest (>330 mg/day) compared with the lowest (<200 mg/day) quintile of caffeine intake was associated with a modestly increased risk of fracture: HR 1.20 (95% CI: 1.07-1.35). A high coffee consumption significantly increased the risk of fracture (p for trend 0.002), whereas tea drinking was not associated with risk. The increased risk of fracture with both a high caffeine intake and coffee consumption was confined to women with a low calcium intake (<700 mg/day): HR 1.33 (95% CI: 1.07-1.65) with > or =4 cups (600 ml)/day of coffee compared to <1 cup (150 ml)/day. The same comparison but risk estimated for women with a high propensity for fractures (> or =2 fracture types) revealed a HR of 1.88 (95% CI: 1.17-3.00).
In conclusion, our results indicate that a daily intake of 330 mg of caffeine, equivalent to 4 cups (600 ml) of coffee, or more may be associated with a modestly increased risk of osteoporotic fractures, especially in women with a low intake of calcium.
Hallström H, Wolk A, Glynn A, Michaëlsson K
Osteoporos Int 2006
Coffee, tea, and the risk of hip fracture: a meta-analysis.
The present meta-analysis shows no clear association between coffee consumption and the risk of hip fractures. There was a nonlinear association between tea consumption and the risk of hip fracture. Compared to no tea consumption, drinking 1-4 cups of tea daily was associated with a lower risk of hip fracture.
Prospective cohort and case-control studies have suggested that coffee and tea consumption may be associated with the risk of hip fracture; the results have, however, been inconsistent. We conducted a meta-analysis to assess the association between coffee and tea consumption and the risk of hip fracture.
We performed systematic searches using MEDLINE, EMBASE, and OVID until February 20, 2013, without limits of language or publication year. Relative risks (RRs) with 95% confidence intervals (CI) were derived using random-effects models throughout all analyses. We conducted categorical, dose-response, heterogeneity, publication bias, and subgroup analyses.
Our study was based on 195,992 individuals with 9,958 cases of hip fractures from 14 studies, including six cohort and eight case-control studies. The pooled RRs of hip fractures for the highest vs. the lowest categories of coffee and tea consumption were 0.94 (95% CI 0.71-1.17) and 0.84 (95% CI 0.66-1.02), respectively. For the dose-response analysis, we found evidence of a nonlinear association between tea consumption and the risk of hip fracture (p(nonlinearity) < 0.01). Compared to no tea consumption, 1-4 cups of tea per day may reduce the risk of hip fracture by 28% (0.72; 95% CI 0.56-0.88 for 1-2 cups/day), 37% (0.63; 95% CI 0.32-0.94 for 2-3 cups/day), and 21% (0.79; 95% CI 0.62-0.96 for 3-4 cups/day).
We found no significant association between coffee consumption and the risk of hip fracture. A nonlinear association emerged between tea consumption and the risk of hip fracture; individuals drinking 1-4 cups of tea per day exhibited a lower risk of hip fractures than those who drank no tea. The association between 5 daily cups of tea, or more, and hip fracture risk should be investigated.
Sheng J, Qu X, Zhang X, Zhai Z…
Osteoporos Int Jan 2014
Evidence for a prospective anti-osteoporosis effect of black tea (Camellia Sinensis) extract in a bilaterally ovariectomized rat model.
The purpose of this study was to examine whether whole aqueous black tea extract (BTE) prevents bone loss induced by ovarian hormone deficiency. Eighteen 95-100 days old female albino rats were randomly assigned to three treatment groups [sham -operated control (sham); bilaterally ovariectomized (ovx) and ovx + aqueous black tea extract (BTE) ] and sacrificed after 28 days. All animals were fed a standard laboratory diet with free access to deionized water except on days of urinary parameter studies when animals were given only calcium free deionized water during the entire 24 h period of urine collection. Body weight study revealed that rats in the ovx group had significantly higher final body weight than rats in the sham group. This higher final body weight was not observed in animals receiving BTE. The ovx group also had significantly higher abdominal fat mass and liver weight and significantly lower uterus, right kidney and left kidney weights than in other two groups. All these organ weight changes in ovx group also were not observed in animals receiving BTE. Results of urinary studies revealed that rats in the ovx group had significantly higher urinary excretion of calcium (Ca), phosphate, creatinine (Cr), calcium to creatinine (Ca:Cr) ratio (P< 0.001) and hydroxyproline (HPr) (P< 0.01) than rats in the sham group. Significant recovery of all these parameters were observed in animals receiving BTE. The ovx group also had significantly higher (P< 0.001) serum alkaline phosphatase (AP) and tartrate-resistant acid phosphatase (TRAP) activity than rats in the other two groups. These changes could not be seen in animals receiving BTE. Also, identical changes were seen in bone density experiments. Rats in the ovx group had significantly lower densities of the right femur (P<0.001), eighth thoracic rib (P< 0.001), eighth thoracic vertebra (P< 0.05), and fourth lumbar vertebra (P< 0.01) than rats in the sham group; and significant improvement in densities of these bones were seen in animals supplemented with BTE. Animals of ovx group also showed significant decrease in calcium and phosphate level in all these bones which could be regained significantly when these animals were supplemented with BTE. Our findings suggest that aqueous BTE may be effective in preventing bone loss due to ovarian hormone deficiency. Because serum activity of AP, TRAP and urinary loss of bone minerals (Ca and Phosphate) and also the organic components of bone (Cr and HPr) were significantly greater in the ovx group, compared to sham animals and ovx + BTE group. This confirms that ovariectomy enhances and BTE suppresses the rate of bone turnover. The density results of ovx + BTE group are significantly greater than rats in the ovx group, suggesting further that formation exceeded resorption. Detailed studies are underway to clarify the mechanism of this protective effect of BTE on hypogonadal bone loss.
Das AS, Mukherjee M, Mitra C
Asia Pac J Clin Nutr 2004
PMID: 15228990 | Free Full Text
Protective effect of green tea polyphenols on bone loss in middle-aged female rats.
Recent studies have suggested that green tea polyphenols (GTP) are promising agents for preventing bone loss in women. Findings that GTP supplementation resulted in increased urinary GTP concentrations and bone mass via an increase of antioxidant capacity and/or a decrease of oxidative stress damage suggest a significant role of GTP in bone health of women.
Recent studies suggested that green tea polyphenols (GTP) are promising agents for preventing bone loss in women. However, the mechanism related to the possible protective role of GTP in bone loss is not well understood.
This study evaluated bioavailability, mechanisms, bone mass, and safety of GTP in preventing bone loss in middle-aged rats without (sham, SH) and with ovariectomy (OVX).
A 16-week study of 2 (SH vs. OVX) x 3 (no GTP, 0.1% GTP, and 0.5% GTP in drinking water) factorial design using 14-month-old female rats (n = 10/group) was performed. An additional 10 rats in baseline group were euthanized at the beginning of study to provide baseline parameters.
There was no difference in femur bone mineral density between baseline and the SH+0.5% GTP group. Ovariectomy resulted in lower values for liver glutathione peroxidase activity, serum estradiol, and bone mineral density. GTP supplementation resulted in increased urinary epigallocatechin and epicatechin concentrations, liver glutathione peroxidase activity and femur bone mineral density, decreased urinary 8-hydroxy-2′-deoxyguanosine and urinary calcium levels, but no effect on serum estradiol and blood chemistry levels.
We conclude that a bone-protective role of GTP may contribute to an increase of antioxidant capacity and/or a decrease of oxidative stress damage.
Shen CL, Wang P, Guerrieri J, Yeh JK…
Osteoporos Int Jul 2008
Tea drinking is associated with benefits on bone density in older women.
Impaired hip structure assessed by dual-energy X-ray absorptiometry (DXA) areal bone mineral density (aBMD) is an independent predictor for osteoporotic hip fracture. Some studies suggest that tea intake may protect against bone loss.
Using both cross-sectional and longitudinal study designs, we examined the relation of tea consumption with hip structure. Randomly selected women (n = 1500) aged 70-85 y participated in a 5-y prospective trial to evaluate whether oral calcium supplements prevent osteoporotic fractures. aBMD at the hip was measured at years 1 and 5 with DXA. A cross-sectional analysis of 1027 of these women at 5 y assessed the relation of usual tea intake, measured by using a questionnaire, with aBMD. A prospective analysis of 164 women assessed the relation of tea intake at baseline, measured by using a 24-h dietary recall, with change in aBMD from years 1 to 5.
In the cross-sectional analysis, total hip aBMD was 2.8% greater in tea drinkers (x: 806; 95% CI: 797, 815 mg/cm(2)) than in non-tea drinkers (784; 764, 803 mg/cm(2)) (P < 0.05). In the prospective analysis over 4 y, tea drinkers lost an average of 1.6% of their total hip aBMD (-32; -45, -19 mg/cm(2)), but non-tea drinkers lost 4.0% (-13; -20, -5 mg/cm(2)) (P < 0.05). Adjustment for covariates did not influence the interpretation of results.
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, Hodgson JM, Dick IM, Prince RL
Am. J. Clin. Nutr. Oct 2007
PMID: 17921409 | Free Full Text
Phytonutrients for bone health during ageing.
Osteoporosis is a skeletal disease characterized by a decrease in bone mass and bone quality that predispose an individual to an increased risk of fragility fractures. Evidence demonstrating a positive link between certain dietary patterns (e.g. Mediterranean diet or high consumption of fruits and vegetables) and bone health highlights an opportunity to investigate their potential to protect against the deterioration of bone tissue during ageing. While the list of these phytonutrients is extensive, this review summarizes evidence on some which are commonly consumed and have gained increasing attention over recent years, including lycopene and various polyphenols (e.g. polyphenols from tea, grape seed, citrus fruit, olive and dried plum). Evidence to define a clear link between these phytonutrients and bone health is currently insufficient to generate precise dietary recommendations, owing to mixed findings or a scarcity in clinical data. Moreover, their consumption typically occurs within the context of a diet consisting of a mix of phytonutrients and other nutrients rather than in isolation. Future clinical trials that can apply a robust set of outcome measurements, including the determinants of bone strength, such as bone quantity (i.e. bone mineral density) and bone quality (i.e. bone turnover and bone microarchitecture), will help to provide a more comprehensive outlook on how bone responds to these various phytonutrients. Moreover, future trials that combine these phytonutrients with established bone nutrients (i.e. calcium and vitamin D) are needed to determine whether combined strategies can produce more robust effects on skeletal health.
Sacco SM, Horcajada MN, Offord E
Br J Clin Pharmacol Mar 2013