 |
|
Epidemiological Evidence of Increased Bone Mineral Density in Habitual Tea Drinkers
Chih-Hsing Wu, MD;
Yi-Ching Yang, MD;
Wei-Jen Yao, MD;
Feng-Hwa Lu, MD;
Jin-Shang Wu, MD;
Chih-Jen Chang, MD
Arch Intern Med. 2002;162:1001-1006.
ABSTRACT
| |
Background Researchers have hypothesized that bone mineral density (BMD) may be
influenced by chemical compounds such as caffeine, phytoestrogen, fluoride,
and many compounds that are contained in tea extracts. Hence, the relationship
between habitual tea consumption and BMD is an interesting issue.
Methods Based on an epidemiological survey, we enrolled 497 men and 540 women,
30 years and older, in our study. All subjects were questioned about their
habit of tea consumption and other lifestyle characteristics by means of a
structured questionnaire. Dual-energy x-ray absorptiometry was used to measure
the BMD of the total body, lumbar spine (L1-L4), hip neck, and Ward triangle
regions.
Results Five hundred two subjects (48.4%) were habitual tea drinkers, with a
mean duration of tea consumption of approximately 10 years. Compared with
nonhabitual tea drinkers, subjects with habitual tea consumption of 6 to 10
years showed higher lumbar spine BMDs, and those with consumption of more
than 10 years showed the highest BMDs of all measured regions. Under the multiple
stepwise regression models, sex, age, body mass index, total physical activity,
and habit of tea consumption were the major significant variables for the
different BMD regions. Regarding the behavioral characteristics of tea consumption,
the duration of tea consumption was the only independent determinant for the
BMDs.
Conclusion Habitual tea consumption, especially for more than 10 years, has significant
beneficial effects on BMD of the total body, lumbar spine, and hip regions
in adults.
INTRODUCTION
TEA, AN EXTRACT of the leaves of the Camellia sinensis, is commonly consumed throughout the world. According to the different
levels of fermentation, tea is categorized into green (nonfermented), oolong
(partially fermented), and black (fermented) types. In most Western countries,
black tea with milk is preferred, whereas in China, green or oolong tea is
usually consumed without milk. Tea contains more than 4000 chemical compounds
that may affect the human body in many aspects.1
Recent studies have demonstrated that tea and tea polyphenols have many positive
effects on the prevention of cardiovascular disease, atherosclerosis, and
cancer.2
However, tea extracts also contain high concentrations of caffeine,
fluoride, flavonoids, and phytoestrogen. These compounds have all been supposed
to have detrimental or beneficial effects on bone mineral density (BMD) and
risk for fracture in different studies.3-9
After water, tea is the most common drink consumed regularly by most adults
in the world. Any effect of tea on bone metabolism would represent a major
public health concern, but information about the effects of tea consumption
on bone mass is limited and unclear. An inverse association between BMD of
the ultradistal radius and tea drinking in women has been noted,3
but positive associations between tea drinking and BMD of the lumbar or the
femoral neck region were reported recently.10-11
Meanwhile, the Mediterranean Osteoporosis (MEDOS) Study also hypothesized
the protective effect of tea drinking on hip fracture.12-13
These varying findings may result from different study designs (epidemiological
or hospital based), inconsistent definition of tea intake categories, and
incomplete adjustment of the confounding effect of lifestyle characteristics
such as exercise, alcohol intake, smoking, and even the intake of other nutrients.
However, only white subjects who drink black tea have been studied in these
reports, which is a major shortcoming. Furthermore, except for the male MEDOS
Study,12 only female tea drinkers have been
studied. Therefore, our study was designed to evaluate the effect of tea drinking
on BMD in male and female subjects concomitantly. We assessed the relationship
between the 3 different types of tea extracts consumed and BMD, taking into
account the potential confounding factors of age, sex, obesity, total physical
activity, alcohol consumption, smoking, and intake of coffee, milk, and calcium
supplements, in an epidemiological-based Chinese male and female population.
We tried to answer the following 3 questions: (1) Is there any significant
relationship between tea consumption and BMD? (2) Does a dose-response effect
exist between tea consumption and BMD? (3) Which characteristics of tea consumption
are the major influencing factors on BMD?
MATERIALS AND METHODS
SUBJECTS
The study population was enrolled from a prospective epidemiological
survey of chronic diseases in Tainan, a city located in southern Taiwan with
a population of 700 000.14 The selection
procedure was a stratified, systemic, step-by-step cluster sample of households
throughout Tainan. First, the city was grouped formally into 7 administrative
districts. One area (Li, an administrative unit, subdivided from districts
of the city) was randomly selected from each district. Second, every fifth
household within each of the 7 selected areas was identified systematically.
Third, all of the sampled subjects 20 years or older according to the government
population register in 1995 were included in the study. Finally, this cohort
consisted of 2416 eligible Chinese subjects (47.6% men) who underwent systematic
sampling from Tainan. From January 15, 1996, through December 1, 1996, 1638
subjects older than 20 years had participated in the first screening survey.14 In this study, 1225 men and women who completed the
second follow-up survey from September 24, 1998, through January 22, 2000,
underwent analysis. As the physiological peak bone mass is usually achieved
after 30 years of age, we enrolled a total of 1037 subjects (497 men and 540
women) 30 years or older for final analysis. These subjects had no bone-remodeling
disease and had received no bone-remodeling agents. Written consents were
obtained from all the subjects. The research committee of National Cheng Kung
University Hospital, Tainan, approved this study.
QUESTIONNAIRE OF LIFESTYLE COVARIATES
All subjects were interviewed according to the structured questionnaires.
Total physical activity, including leisure activity, occupational activity,
and walking for exercise, was calculated as metabolic equivalent (MET)-hours
per week for all activities for the past year.14-16
Smoking was dichotomized into nonsmoking (never, former, and <1 pack per
month smokers) and current smoking (>1 pack per month). Subjects who had drunk
alcohol, coffee, or milk more than once a week for 6 months or longer were
recorded as habitual drinkers; otherwise, they were classified as nonhabitual
drinkers. Calcium supplementation was also recorded if subjects regularly
used supplements more than 3 times a week for 6 months or more. Personal medical
history, including estrogen replacement therapy, menopausal status, use of
bone-remodeling agents, or presence of related diseases, was checked accordingly.
TEA CONSUMPTION
The level of tea consumption was assessed using a modified questionnaire
at the 1996-1997 and 1998-2000 surveys.11, 17
The first question was: "Have you drunk tea habitually once a week for at
least 6 months?" Subjects who answered yes were coded as habitual tea drinkers
in this study. The habitual tea drinkers then completed the following questions:
(1) What kind of tea (green, black, or oolong) was mostly consumed? (2) Do
you regularly add milk to your tea? (3) How often do you drink tea each week?
(4) How many times do you drink tea each day? (5) How much tea (in milliliters)
do you drink each time? (6) How many years have you been drinking tea in this
way? The average daily tea consumption (in milliliters) was calculated using
the following formula:
For example, if someone drinks 350 mL of tea twice a day and 3 days
per week, the average daily tea consumption would be (3 x 2 x
350)/7 = 300 mL.
BONE MINERAL DENSITY
With each subject wearing light indoor clothes, we measured body height
and weight and calculated body mass index (BMI; weight in kilograms divided
by the square of height in meters). During the 1998-2000 follow-up survey,
the BMDs, including total body, lumbar spine (L1-L4), and hip neck and Ward
triangle regions, were measured by means of dual-energy x-ray absorptiometry
(DPX-L; Lunar Radiation Corporation, Madison, Wis). The analyzing software
(version 1.3z; Lunar Radiation Corporation) was used to calculate the body
composition and was not changed during this study period, as it could provide
consistent results with similar high coefficients of variation compared with
a newer version of the software. In this study, the coefficients of variation
of BMDs were 0.5% for total body, 2.0% for spine, and 0.9% for legs.
STATISTICAL ANALYSIS
Data were analyzed using SPSSWIN software (Version 8.0; SPSS Inc, Chicago,
Ill). We categorized subjects into the following 4 subgroups according to
duration of tea consumption: nonhabitual, 1 to 5 years, 6 to 10 years, and
more than 10 years. We subjected the differences of BMDs among the 4 subgroups
to analysis of covariance, which adjusted for age, BMI, sex, and all other
lifestyle covariates. We analyzed the independent effects of tea consumption,
the different characteristics of tea consumption, and all other lifestyle
covariates on BMDs using multiple stepwise linear regression models. Each
independent variable was expressed with standardized regression coeffients.
Statistical significance was defined as P<.05
for 2-tailed analysis.
RESULTS
Of the 1037 subjects, 48.4% were habitual tea drinkers; 26.0%, current
smokers; 19.3%, habitual alcohol drinkers; 57.0%, habitual milk drinkers;
11.3%, habitual coffee drinkers; and 7.2%, habitual calcium supplement users.
To assess the dose-response effect of tea consumption on BMD, the following
numbers of subjects were categorized into the 4 subgroups by duration of tea
consumption: 535 as nonhabitual, 226 as 1 to 5 years, 152 as 6 to 10 years,
and 124 as more than 10 years (Table 1).
Among the 502 habitual tea drinkers, 45 (9.0%) were black tea drinkers and
457 (91.0%) were green or oolong tea drinkers. Two hundred fifty-three habitual
tea drinkers consumed tea daily, but only 96 subjects had the habit of adding
milk during tea consumption. The mean ± SD duration of habitual tea
drinking was 9.5 ± 9.4 years (range, 1-60 years), with a mean ±
SD daily tea consumption of 414.4 ± 452.4 mL.
|
|
|
|
Table 1. Basic Characteristics of Nonhabitual and Habitual Tea Drinkers
in 1037 Study Subjects*
|
|
|
In Figure 1, a positive linear
effect correlating to duration of habitual tea consumption was found in the
BMD of the 4 body regions. After adjustment for sex, age, BMI, and lifestyle
covariates, the BMD for the total body, lumbar spine, and hip neck and Ward
triangle regions were highest among subjects who consumed tea habitually for
more than 10 years compared with the other 3 subgroups. On the other hand,
subjects who consumed tea habitually for 6 to 10 years had significantly higher
lumbar spine BMDs than the nonhabitual tea drinkers. However, no significant
difference in BMD was found between tea drinkers with 1 to 5 years' duration
and nonhabitual tea drinkers. When we statistically analyzed the behavioral
characteristics of tea consumption with all lifestyle covariates, the duration
of habitual tea consumption was the only significant determinant of all measured
BMD among the behavioral characteristics of tea consumption (Table 2).
|
|
|
|
Dose-response effect between the duration of habitual tea consumption
and bone mineral density (BMD) in 4 regions. We performed statistical analysis
by analysis of covariance, adjusted for age, sex, body mass index, total physical
activity, use of calcium supplements, smoking and drinking habits, and coffee
and milk intake. Data are expressed as adjusted mean ± SE.
|
|
|
|
|
|
|
Table 2. Multiple Stepwise Regression Models of Tea Consumption, Associated
Lifestyle Factors, and BMD in 1037 Subjects*
|
|
|
The independent effects of other covariates on BMD are shown in Table 3. Men had higher BMDs than women.
The BMD increased along with the increment of BMI, but decreased with the
increment of age. Total physical activity also had a positive effect on BMD
of the total body and hip neck. After analysis with all of the covariates,
tea consumption was still a small but significantly positive variable on BMD
of the total body, lumbar spine, and hip (hip neck and Ward triangle regions).
In other words, the habit of tea consumption can predict a 0.5% to 5.1% variation
in BMD in the different 4 body regions. Moreover, after adjustment for all
covariates, no significant differences of BMD could be found between those
who drank green or oolong tea compared with those who drank black tea (data
not shown).
|
|
|
|
Table 3. Multiple Stepwise Regression Models of Tea Consumption, Associated
Lifestyle Factors, and BMD Density in 1037 Subjects*
|
|
|
COMMENT
Consistent with the findings of other studies,10-11
the protective effect of tea on BMD of the total body, lumbar spine, and hip
regions was clearly demonstrated. To the best of our knowledge, this is the
first study of the relationship between consumption of 3 kinds of tea (green,
black, and oolong) and BMD in both sexes concomitantly. Similar to previous
reports,18-21
we also demonstrated that younger men, those with higher BMIs, and those who
expend higher total physical activity have higher BMDs. Furthermore, even
after adjustment for menopausal status, tea consumption was still an independent
factor for BMD in women (data not shown). However, the effect of smoking and
intake of alcohol, milk, coffee,22 and calcium
supplements10 on BMD was obscure in our study,
which was also compatible with the various findings in previous studies.12-13,20, 23 Generally
speaking, the similarity of major findings between other reports and ours
suggested that our study population is not a unique group and that our findings
could be extrapolated to other populations.
Although several studies may have suggested the positive effect of tea
consumption on bone mass,10-13
no consistent methods in defining the categorization of tea consumption have
been used. In previous studies, "cups of tea consumed"10-13
was the most common definition of the level of tea consumption. However, we
found that the duration of tea consumption, not the amount of daily tea consumption,
was the only independent determinant of BMD. As we know, the change of BMD
is always gradual. If BMD could be affected by tea consumption, the exposure
must be long enough to have a significant cumulative effect on BMD, ie, long-term,
moderate tea consumption will influence BMD more than short-term consumption
of high amounts of tea. Therefore, the duration of tea consumption was the
major determinant of BMD among all the characteristics of tea consumption.
Nevertheless, whether this unique finding could be a bias due to different
drinking habits between Asians and other populations is debatable and needs
further investigation.
Another important issue was to determine the threshold or range of tea
consumption likely to be beneficial or detrimental for BMD effects. Although
tea consumption (cups of tea consumed and recorded on a 4-point score) was
found to have a protective effect on hip fracture, the dose-response effect
has not been discussed in the MEDOS Study or in other studies.12-13
In our study, we found that subjects with habitual tea consumption from 6
to 10 years' duration had significantly higher BMD of the lumbar spine than
did nonhabitual tea drinkers. When the duration of tea consumption was more
than 10 years, the significant increment in BMD of the total body, lumbar
spine, and hip regions was recorded when compared with that of nonhabitual
tea drinkers (Figure 1). Hence,
it is plausible to believe that a graded association between increasing duration
of tea consumption and elevation of BMD for the total body, lumbar spine,
and hip regions existed in our study. The difference between the BMDs in black
tea and green or oolong tea drinkers may also be of interest. After adjustment
for covariates, no significant differences of BMDs could be found between
green or oolong tea and black tea drinkers (data not shown). Perhaps relatively
too few black tea drinkers were included (n = 45) to have a balanced comparison
of their BMDs with those of green/oolong tea drinkers (n = 457), especially
with adjustment for other covariates.
Several hypotheses have been proposed to explain the bone-protective
effects of tea. These hypotheses may work independently or in concert. First,
tea is an important source of dietary fluoride.24-25
Fluoride intake can alleviate the osteoporotic progression.5-7,26
Therefore, the relatively high fluoride content of tea leaves may enhance
the protective effect on BMD. Second, flavonoids (including phytoestrogen
and ipriflavone) have all been supposed to improve the BMD.4, 27
Because tea contains relatively high amounts of flavonoids and phytoestrogen,1, 9, 28 increasing the BMD
by consuming tea habitually is possible. Third, experiments have also found
that tea extracts could inhibit bone resorption27
and protect against clastogenic activity of mouse bone29
in vivo. Finally, the different effects of tea infusions (eg, polyphenols
and tannins) on the milieu of elemental mineral metabolism may also indirectly
influence BMD.30-32
These hypotheses may work independently or in concert and could explain the
protective effect of tea consumption on BMD.
In this study, a range of lifestyle cofactors predicted the BMD, but
together these factors explain only a small proportion of the overall BMD
(the highest adjusted R2 is 0.392). Many
unknown factors such as genetic factors33 may
influence BMD and need to be studied in the future. Our results suggest a
possible way of reconciling the disparate reports from previous studies, ie,
habitual tea consumption, especially when maintained for more than 10 years,
has a significantly beneficial effect on BMD of the total body, lumbar spine,
and hip regions in men and women.
AUTHOR INFORMATION
Accepted for publication September 13, 2001.
This study was supported by the grants from the National Science Council,
Taipei, Taiwan (NSC-89-2314-B-006-044) and National Cheng Kung University
Hospital (NCKUH-88-051).
We thank Ma Mi-Chia, PhD, associate professor in the Department of Statistics
of National Cheng Kung University, for statistical counseling; Chen Chia-Min
for statistical assistance; and Chang Yu-Fung for administrative assistance.
Corresponding author and reprints: Chih-Jen Chang, MD, Department
of Family Medicine, National Cheng Kung University Hospital, 138 Sheng-Li
Rd, Tainan 70428, Taiwan (e-mail: em75210{at}email.ncku.edu.tw).
From the Departments of Family Medicine (Drs C.-H. Wu, Yang, Lu, J.-S.
Wu, and Chang) and Nuclear Medicine (Dr Yao), National Cheng Kung University
Hospital, Tainan, Taiwan.
REFERENCES
| |
1. Finger A, Kuhr S, Engelhardt UH. Chromatography of tea constituents. J Chromatogr. 1992;624:293-315.
FULL TEXT
|
ISI
| PUBMED
2. Weisburger JH. Tea and health: the underlying mechanisms. Proc Soc Exp Biol Med. 1999;220:271-275.
FULL TEXT
| PUBMED
3. Hernandez-Avila M, Stampfer MJ, Ravnikar VA, et al. Caffeine and other predictors of bone density among pre- and perimenopausal
women. Epidemiology. 1993;4:128-134.
ISI
| PUBMED
4. de Aloysio D, Gambacciani M, Altieri P, et al. Bone density changes in postmenopausal women with the administration
of ipriflavone alone or in association with low-dose ERT. Gynecol Endocrinol. 1997;11:289-293.
ISI
| PUBMED
5. Hillier S, Cooper C, Kellingray S, Russell G, Hughes H, Coggon D. Fluoride in drinking water and risk of hip fracture in the UK: a case-control
study. Lancet. 2000;355:265-269.
FULL TEXT
|
ISI
| PUBMED
6. Riggs BL, O'Fallon WM, Lane A, et al. Clinical trial of fluoride therapy in postmenopausal osteoporotic women:
extended observations and additional analysis. J Bone Miner Res. 1994;9:265-275.
ISI
| PUBMED
7. Riggs BL, Hodgson SF, O'Fallon WM, et al. Effect of fluoride treatment on the fracture rate in postmenopausal
women with osteoporosis. N Engl J Med. 1990;322:802-809.
ABSTRACT
8. Arjmandi BH, Birnbaum RS, Juma S, Barengolts E, Kukreja SC. The synthetic phytoestrogen, ipriflavone, and estrogen prevent bone
loss by different mechanisms. Calcif Tissue Int. 2000;66:61-65.
FULL TEXT
|
ISI
| PUBMED
9. Li J, Li H, Kodota S, Namba T, Miyahara T, Khan UG. Effects on cultured neonatal mouse calcaria of the flavonoids isolated
from Boerhaavia repens. J Nat Prod. 1996;59:1015-1018.
FULL TEXT
| PUBMED
10. Hoover PA, Webber CE, Beaumont LF, Blake JM. Postmenopausal bone mineral density: relationship to calcium intake,
calcium absorption, residual estrogen, body composition, and physical activity. Can J Physiol Pharmacol. 1996;74:911-917.
FULL TEXT
|
ISI
| PUBMED
11. Hegarty VM, May HM, Khaw KT. Tea drinking and bone mineral density in older women. Am J Clin Nutr. 2000;71:1003-1007.
FREE FULL TEXT
12. Kanis J, Johnell O, Gullberg B, et al. Risk factors for hip fracture in men from southern Europe: the MEDOS
Study. Osteoporos Int. 1999;9:45-54.
FULL TEXT
|
ISI
| PUBMED
13. Johnell O, Gullberg B, Kanis JA, et al. Risk factors for hip fracture in European women: the MEDOS Study. J Bone Miner Res. 1995;10:1802-1815.
ISI
| PUBMED
14. Lu FH, Yang YC, Wu JS, Wu CH, Chang CJ. A population-based study of the prevalence and associated factors of
diabetes mellitus in southern Taiwan. Diabet Med. 1998;15:564-572.
FULL TEXT
|
ISI
| PUBMED
15. Kriska AM, Bennett PH. An epidemiological prospective of the relationship between physical
activity and NIDDM: from activity assessment to intervention. Diabetes Metab Rev. 1992;8:355-372.
ISI
| PUBMED
16. Paffenbarger RS Jr, Blair SN, Lee IM, Hyde RT. Measurement of physical activity to assess health effects in free-living
populations. Med Sci Sports Exerc. 1993;25:60-70.
FULL TEXT
|
ISI
| PUBMED
17. Dequeker J, Ranstam J, Valson J, Sigurgevisson B, Allander E for the MEDOS Study Group. The Mediterranean Osteoporosis (MEDOS) Study Questionnaire. Clin Rheumatol. 1991;10:54-72.
FULL TEXT
|
ISI
| PUBMED
18. Gregg EW, Cauley JA, Seeley DG, Ensrud KE, Bauer DC for the Study of Osteoporotic Fractures Research Group. Physical activity and osteoporotic fracture in older women. Ann Intern Med. 1998;129:81-88.
FREE FULL TEXT
19. Greendale GA, Barrett-Connor E, Edelstein S, Ingles S, Haile R. Lifetime leisure exercise and osteoporosis: the Rancho Bernardo Study. Am J Epidemiol. 1995;141:951-959.
FREE FULL TEXT
20. Bauer DC, Browner WS, Cauley JA, et al for the Study of Osteoporotic Fractures Research Group. Factors associated with appendicular bone mass in older women. Ann Intern Med. 1993;118:657-665.
FREE FULL TEXT
21. Kao Ch, Chen CC, Wang SJ. Normal data for lumbar spine bone mineral content in healthy elderly
Chinese: influences of sex, age, obesity and ethnicity. Nucl Med Commun. 1994;15:916-920.
ISI
| PUBMED
22. Barrett-Connor E, Chang JC, Edelstein SL. Coffee-associated osteoporosis offset by daily milk consumption: the
Rancho Bernardo Study. JAMA. 1994;271:280-283.
FREE FULL TEXT
23. Cumming RG, Klineberg RJ. Case-control study of risk factors for hip fractures in the elderly. Am J Epidemiol. 1994;139:493-503.
FREE FULL TEXT
24. Kao PC, Li HG. The fluoride content of Taiwan tea. Chin Med J (Engl). 1968;15:119-123.
25. Gulati P, Singh V, Gupta MK, Vaidya V, Dass S, Prakash S. Studies on the leaching of fluoride in tea infusions. Sci Total Environ. 1993;138:213-222.
FULL TEXT
| PUBMED
26. Pak CYC, Sakhaee K, Piziak V, et al. Slow-release sodium flouride in the management of postmenopausal osteoporosis:
a randomized controlled trial. Ann Intern Med. 1994;120:625-632.
FREE FULL TEXT
27. Delaisse JM, Eeckhout Y, Vaes G. Inhibition of bone resorption in culture by (+)-catechin. Biochem Pharmacol. 1986;35:3091-3094.
FULL TEXT
|
ISI
| PUBMED
28. Lakenbrink C, Lapczynski S, Maiwald B, Engelhardt UH. Flavonoids and other polyphenols in consumer brews of tea and other
caffeinated beverages. J Agric Food Chem. 2000;48:2848-2852.
FULL TEXT
|
ISI
| PUBMED
29. Mukherjee P, Sarkar D, Sharma A. Effects of dietary consumption of black tea infusion alone and in combination
with known clastogens on mouse bone marrow chromosomes in vivo. Food Chem Toxicol. 1997;35:657-661.
FULL TEXT
|
ISI
| PUBMED
30. Greger JL, Lyle BJ. Iron, copper and zinc metabolism of rats fed various levels and types
of tea. J Nutr. 1988;118:52-60.
31. Chang MCJ, Bailey JW, Collins JL. Dietary tannins from cowpeas and tea transiently alter apparent calcium
absorption but not absorption and utilization of protein in rats. J Nutr. 1994;124:283-288.
32. Zeyuan D, Bingying T, Xiaolin L, Jinming H, Yifeng C. Effect of green tea and black tea on the metabolisms of mineral elements
in old rats. Biol Trace Elem Res. 1998;65:75-86.
ISI
| PUBMED
33. Eisman JA. Genetics of osteoporosis. Endocr Rev. 1999;20:788-804.
FREE FULL TEXT
 CiteULike  Connotea  Del.icio.us  Digg  Reddit  Technorati  Twitter
What's this?
RELATED ARTICLE
Archives of Internal Medicine Reader's Choice: Continuing Medical Education
Arch Intern Med. 2002;162(9):1071-1072.
FULL TEXT
THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
|
Consumption of Green Tea Extract Results in Osteopenia in Growing Male Mice
Iwaniec et al.
J. Nutr. 2009;139:1914-1919.
ABSTRACT
| FULL TEXT
Higher dietary flavone, flavonol, and catechin intakes are associated with less of an increase in BMI over time in women: a longitudinal analysis from the Netherlands Cohort Study
Hughes et al.
Am. J. Clin. Nutr. 2008;88:1341-1352.
ABSTRACT
| FULL TEXT
Tea drinking is associated with benefits on bone density in older women
Devine et al.
Am. J. Clin. Nutr. 2007;86:1243-1247.
ABSTRACT
| FULL TEXT
Fluoride-Related Bone Disease Associated With Habitual Tea Consumption
Johnson et al.
Mayo Clin Proc. 2007;82:719-724.
ABSTRACT
| FULL TEXT
Habitual Tea Consumption and Risk of Osteoporosis: A Prospective Study in the Women's Health Initiative Observational Cohort
Chen et al.
Am J Epidemiol 2003;158:772-781.
ABSTRACT
| FULL TEXT
|
