Wednesday, 10 January 2018

Re: Consumption of Yerba Maté Does Not Affect Fracture Risk in Postmenopausal Women

Yerba Maté (Ilex paraguariensis, Aquifoliaceae) Osteoporosis Date: 12-29-2017 HC# 121771-583 da Veiga DTA, Bringhenti R, Bolignon AA, et al. The yerba mate intake has a neutral effect on bone: A case-control study in postmenopausal women. Phytother Res. October 13, 2017; [epub ahead of print]. doi: 10.1002/ptr.5947. As the world's population ages, osteoporosis is increasing. Osteoporosis is an age-related decline in bone mineral density (BMD) occurring when the breakdown of bone exceeds its creation. Osteoporosis makes bones weak and can lead to fractures that increase morbidity and mortality. BMD is also affected by caffeinated beverages. While consumption of coffee (Coffea spp., Rubiaceae) is associated with increased risk of fractures, green and black tea (Camellia sinensis, Theaceae) consumption is associated with a lower risk. The leaves of yerba maté (Ilex paraguariensis, Aquifoliaceae), a plant native to South America, are used to make a tea called "Chimarrão." This tea is caffeinated, but recent studies have associated its consumption with improved BMD in postmenopausal women. A yerba maté hot water infusion prepared by the authors contained gallic acid, isochlorogenic acid, caffeic acid, catechin, epigallocatechin, quercetin, rutin, kaempferol, caffeine, and theobromine; some of these ingredients may strengthen bone. The purpose of this case-control study was to evaluate the associations between yerba maté tea (maté) consumption and "fragility fractures, calcium homeostasis, bone markers, and oxidative stress." This case-control study was nested in the Copês et al.1 primary-care cross-sectional study on obesity and fractures in postmenopausal women in Santa Maria, Brazil. Women at least 55 years old were recruited from March 1, 2013 to August 31, 2013.1 Of the 1057 postmenopausal women recruited, 46 reported a past fracture after age 45 that could be confirmed by x-ray, and another 49 women who had not reported a fracture were randomly selected to be controls. "Women with cognitive deficits, communication difficulties, and questionnaire [in]completion were excluded from the study." Data were obtained from questionnaires, physical exams, and laboratory tests. Subjects completed an osteoporosis and bone-fracture risk factor questionnaire, Baecke's questionnaire to evaluate physical activity, and a food frequency questionnaire to quantify maté consumption. Maté consumption was graded as yes or no, greater or less than 1 liter a day, and consumption for more, or less, than 10 years. Subjects' weight and height were recorded, their body mass index (BMI) was calculated, and blood samples were drawn to measure total calcium, phosphorus, albumin, creatinine, procollagen type I intact N-terminal propeptide (P1NP), collagen type I C-telopeptide (CTX), vitamin D, parathyroid hormone (PTH), and nitrite/nitrate (NOx). CTX is a marker of bone resorption, while P1NP is a marker of bone formation. Maté drinkers and non-maté drinkers, with quantity and duration of intake not considered, had no statistically significant difference in age (P=0.29), tobacco (Nicotiana tabacum, Solanaceae) use (P=0.80), alcohol use (P=1), or falls (P=0.27). There was a statistically significant difference between the 2 groups in obesity (P=0.027); the non-maté group had a mean BMI of 27.6, versus 30.2 in the maté group. Serum levels of NOx also were significantly elevated in the maté group (mean of 311.8 versus 146.3 in the non-maté group; P=0.017), but there was no statistically significant difference in total fractures (P=0.82), osteoporotic fractures (P=0.99), physical activity levels (P=0.45), total calcium (P=0.64), phosphorus (P=0.11), albumin (P=0.09), creatinine (P=0.35), P1NP (P=0.88), CTX (P=0.66), vitamin D (P=0.58), or PTH (P value not given). Fractures were reported by 48.3% of maté drinkers and 48.5% of non-maté drinkers (P=0.99). In addition, women who had drunk maté for more than 10 years had a significantly higher BMI than those who had drunk it for less than 10 years or not at all (30.9 versus 27.1; P=0.001), and NOx also was significantly elevated (mean of 338.8 versus 144.6; P=0.05); however, there was no statistically significant difference in serum levels of total calcium (P value not given), phosphorus (P value not given), PTH (P value not given), vitamin D (P value not given), P1NP (P value not given), or CTX (P=0.480). Logistic regression to evaluate the likelihood of osteoporotic fractures in maté drinkers revealed a positive association with age (P=0.001), but not maté intake (P=0.73), BMI (P=0.24), or log NOx (P=0.87). The authors conclude that maté consumption does not increase the risk of bone fracture, perhaps because yerba maté's polyphenols counteract the effects of caffeine. While NOx was significantly elevated in the maté group, it did not correlate with P1NP or CTX, and was not associated with osteoporotic fractures. The authors acknowledge that their study could be limited by recall bias and its small sample size, and more studies are needed. Additionally, the fact that women who consumed maté, especially long term, had a significantly higher mean BMI suggests that there may be differences between drinkers and non-drinkers that could confound observational studies. This study was supported by grants from the Federal University of Santa Maria, Brazil, and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). The authors declare no conflict of interest regarding this manuscript. —Heather Anderson, MD Reference 1Copês RM, Comim FV, Langer FW, et al. Obesity and fractures in postmenopausal women: A primary-care cross-sectional study at Santa Maria, Brazil. J Clin Densitom. April-June 2015;18(2):165-171.