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Tea Reduces Fracture Risk

 

All,

 

A new prospective study [1] reported on here found that elderly women who drank the most tea had a 30% reduced risk of osteoporotic fractures compared with women who abstained from drinking tea. In the study, researchers followed ~1200 women age 75+ for 10 years and associated their tea drinking habits with subsequence risk of fracture. Here is the highlight from the abstract:

 

In comparison with the lowest tea
intake category (≤1 cup/wk), consumption of ≥3 cups/d was associated with a 30%
decrease in the risk of any osteoporotic fracture (HR: 0.70; 95% CI: 0.50, 0.96).
Compared with women in the lowest tertile of total flavonoid intake (from tea and
diet), women in the highest tertile had a lower risk of any osteoporotic fracture
(HR: 0.65; 95% CI: 0.47, 0.88), major osteoporotic fracture (HR: 0.66; 95% CI:
0.45, 0.95), and hip fracture (HR: 0.58; 95% CI: 0.36, 0.95).

 

No mention is made of a comparison between the relative effects of black vs. green tea on fracture risk in this cohort. Given the subjects were Australian women, it is likely they were drinking mostly black tea so no meaningful comparison could be made. 

 

I recently started drinking a combination of black and green tea based on suggestive evidence that black tea may have some health benefits that green tea does not, and visa versa. This study could be interested as further (albeit weak) support such a strategy.

 

--Dean 

 

P.S. Here is a nice infographic on the health benefits of Coffee vs. Tea, although bone health isn't mentioned as a benefit for either one.

 

---------------

[1] Am J Clin Nutr. 2015 Oct;102(4):958-65. doi: 10.3945/ajcn.115.109892. Epub 2015
Aug 12.

Tea and flavonoid intake predict osteoporotic fracture risk in elderly Australian
women: a prospective study.

Myers G(1), Prince RL(2), Kerr DA(3), Devine A(4), Woodman RJ(5), Lewis JR(2),
Hodgson JM(6).

BACKGROUND: Observational studies have linked tea drinking, a major source of
dietary flavonoids, with higher bone density. However, there is a paucity of
prospective studies examining the association of tea drinking and flavonoid
intake with fracture risk.
OBJECTIVE: The objective of this study was to examine the associations of black
tea drinking and flavonoid intake with fracture risk in a prospective cohort of
women aged >75 y.
DESIGN: A total of 1188 women were assessed for habitual dietary intake with a
food-frequency and beverage questionnaire. Incidence of osteoporotic fracture
requiring hospitalization was determined through the Western Australian Hospital
Morbidity Data system. Multivariable adjusted Cox regression was used to examine
the HRs for incident fracture.
RESULTS: Over 10 y of follow-up, osteoporotic fractures were identified in 288
(24.2%) women; 212 (17.8%) were identified as a major osteoporotic fracture, and
of these, 129 (10.9%) were a hip fracture. In comparison with the lowest tea
intake category (≤1 cup/wk), consumption of ≥3 cups/d was associated with a 30%
decrease in the risk of any osteoporotic fracture (HR: 0.70; 95% CI: 0.50, 0.96).
Compared with women in the lowest tertile of total flavonoid intake (from tea and
diet), women in the highest tertile had a lower risk of any osteoporotic fracture
(HR: 0.65; 95% CI: 0.47, 0.88), major osteoporotic fracture (HR: 0.66; 95% CI:
0.45, 0.95), and hip fracture (HR: 0.58; 95% CI: 0.36, 0.95). For specific
classes of flavonoids, statistically significant reductions in fracture risk were
observed for higher intake of flavonols for any osteoporotic fracture and major
osteoporotic fracture, as well as flavones for hip fracture (P < 0.05).
CONCLUSION: Higher intake of black tea and particular classes of flavonoids were
associated with lower risk of fracture-related hospitalizations in elderly women
at high risk of fracture.

PMID: 26269364

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[Admin Note: I've changed the title of this thread from "Black Tea Reduces Fracture Risk" to "Tea and Bone Health", both because the above study showing tea was associated with reduced fracture risk didn't distinguish between tea types, and to accommodate this post on green tea and bones. - Dean]

 

All,

 

I'll try to keep this one short, since I sense that some people find my longer posts to be daunting...

 

The above study which found reduced fracture risk from drinking (likely black) tea, was conducted in normal weight elderly women. What about the effects of tea (and green tea specifically) on bone health during CR and/or weight loss? This new study [1] posted by Al Pater address this issue, at least in rats.

 

Study Design:

  • Female rats were made obese by feeding them a High Fat Diet (HFD).
  • Then some of the rats were calorie restricted for four months, while others remained obese on the HFD.
  • Some of each group were supplemented with Green Tea Extract (GTE), and some weren't - resulting in 4 groups: HFD, HFD+GTE, CR, CR+GTE.
  • The bone mineral content (BMC), bone mineral density (BMD), and various parameters of bone strength were measured in the four groups.

Results:

  • Weight loss in the CR group resulted in dramatic reductions in all bone measures - BMC, BMD, and bone strength all dropped a lot.
  • While GTE dramatically improved bone parameters in the obese HFD+GTE group, it had only modest (but statistically significant) benefits on bone health for the CR+GTE group. Bone BMC, BMD and bone strength still dropped in the CR+GTE group relative to HFD & HFD+GTE groups, just not quite as much as CR group.
  • Interestingly, GTE significantly reduced IGF-1 levels in both the HFD+GTE and CR+GTE groups, relative to HFD and CR groups, respectively.

In summary, while green tea may be quite beneficial for bone health under normal dietary conditions, this study suggests it may not help much to maintain or improve bone health under a CR diet.

 

Anyone frustrated by their IGF-1 not dropping as much as they'd like on CR, green tea might be a way to lower IGF-1. Conversely, anyone concerned with too low IGF-1 on CR, cutting out green tea might raise it.

 

--Dean

 

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[1] Green tea supplementation benefits body composition and improves bone properties in obese female rats fed with high-fat diet and caloric restricted diet.

Shen CL, Han J, Wang S, Chung E, Chyu MC, Cao JJ.
Nutr Res. 2015 Dec;35(12):1095-105. doi: 10.1016/j.nutres.2015.09.014. Epub 2015 Oct 5.
PMID: 26525915
 
Abstract
 
This study investigated the effects of green tea polyphenols (GTP) supplementation on body composition, bone properties, and serum markers in obese rats fed a high-fat diet (HFD) or a caloric restricted diet (CRD). Forty-eight female rats were fed an HFD ad libitum for 4 months, and then either continued on the HFD or the CRD with or without 0.5% GTP in water. Body composition, bone efficacy, and serum markers were measured. We hypothesized that GTP supplementation would improve body composition, mitigate bone loss, and restore bone microstructure in obese animals fed either HFD or CRD. CRD lowered percent fat mass; bone mass and trabecular number of tibia, femur and lumbar vertebrae; femoral strength; trabecular and cortical thickness of tibia; insulin-like growth factor-I and leptin. CRD also increased percent fat-free mass; trabecular separation of tibia and femur; eroded surface of tibia; bone formation rate and erosion rate at tibia shaft; and adiponectin. GTP supplementation increased femoral mass and strength (P = .026), trabecular thickness (P = .012) and number (P = .019), and cortical thickness of tibia (P < .001), and decreased trabecular separation (P = .021), formation rate (P < .001), and eroded surface (P < .001) at proximal tibia, and insulin-like growth factor-I and leptin. There were significant interactions (diet type × GTP) on osteoblast surface/bone surface, mineral apposition rate at periosteal and endocortical bones, periosteal bone formation rate, and trabecular thickness at femur and lumbar vertebrate (P < .05). This study demonstrates that GTP supplementation for 4 months benefited body composition and improved bone microstructure and strength in obese rats fed with HFD or HFD followed by CRD diet.
 
KEYWORDS:
 
Body composition; Caloric restriction; Obesity; Osteoporosis; Rat; Tea

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