Comparison of black, green and rooibos tea on osteoblast activity

Abstract

Globally, tea is the second most consumed beverage after water. Habitual tea intake has been associated with higher bone mineral density, particularly in postmenopausal women. This association may be due to its polyphenols and resulting protective antioxidant effects. While in vivo studies have shown improved bone outcomes with a consumption of individual purified tea polyphenols, it is unclear if a particular tea - due to its different profiles of polyphenols - is more beneficial than others. Therefore, we compared three different types of commercially available teas on osteoblasts: green, black and rooibos tea. Tea was normalized to 1 or 10 μg per mL gallic acid equivalents to assess differences in outcomes based on tea profiles rather than the quantity of polyphenol naturally present. The lower level of polyphenols (1 μg per mL gallic acid equivalents) - regardless of tea type and thus polyphenol profile - resulted in greater mineral content as well as cellular and alkaline phosphatase activity in Saos2 cells. Moreover, this was associated with higher markers of differentiation (osteopontin, sclerostin) and reduced cellular toxicity and pro-inflammatory markers (IL6, TNFα). Green, black and rooibos tea improved osteoblast activity at the low level and support epidemiological evidence suggesting tea consumption may benefit bone heath.

Rooibos tea extracts inhibit osteoclast formation and activity through the attenuation of NF-κB activity in RAW264.7 murine macrophages

“…29 Nash et al have reported an increase in mineralization, alkaline phosphatase activity and osteoblast differentiation markers in rooibos-tea treated osteoblast-like cells, in vitro, indicating possible beneficial effects of fermented rooibos tea at 1 and 10 µg ml -1 GAE of tea on bone health. 31 However little is known on the effects of rooibos on osteoclast formation and function. In this present study we made use of concentrations of 62.5-500 µg ml -1 (about 1-14 µg ml -1 GAE) of rooibos tea extracts, similar to the concentrations reported by Nash et al to promote osteoblast differentiation.…”

Geno Protective and Anti-Apoptotic Effect of Green Tea Against Perinatal Lipopolysaccharide-Exposure Induced Liver Toxicity in Rat Newborns

“…The results were different from previously reported studies showing that catechins comprise 30 to 36% of AGTE dry weight, whereas epigallocatechin-3-gallate (EGCG) constitutes up to 63% of the extract (Roomi et al, 2016). However, it is also reported that polyphenol content varies according to brewing time, type of tea, commercial brand and producing country (Nash and Ward, 2016) and this could explain the different polyphenolic content of AGTE in our study.…”

“…Previously reported In vitro finding supported that EGCG, the polyphenolic compound of green tea, has various downstream cytoprotective effects and can induce significant redox-sensitive antioxidant response (Nash and Ward, 2016). The protective activity is modulated with increase in cellular antioxidant mediators such as haeme oxygenase-1, glutathione, and antioxidant and DNA repair enzymes (Soares and Bach, 2009), which decrease basal DNA damage and ultimately cytoprotective prooxidant change.…”

Whey Protein Complexes with Green Tea Polyphenols: Antimicrobial, Osteoblast-Stimulatory, and Antioxidant Activities

“…Here, a similar concentration of polyphenols was used in supplements, which were shown to have reduced release rates during ALP-mediated mineralization. However, it is important to note there are also several studies where treatment with GTE has increased osteoblast differentiation, such as Ko et al [2011] who used rat mesenchymal stem cells, Saos-2 [Nash and Ward, 2016], and human osteoblast cells [Vester et al, 2014]. These cells showed increased levels of many differentiation indicators, including ALP activity, mineralization levels, and gene expression for proteins including sclerostin, osteopontin, and osteocalcin.…”

“…In support of this, other studies using osteoblast-like cells tended to use lower concentrations, compared to the doses of 64 and 128 µg/mL that we used. For example, rat mesenchymal stem cells [Ko et al, 2011], Saos-2 [Nash and Ward, 2016], and human osteoblast cells [Vester et al, 2014] all showed increased levels of cell differentiation and limited cytotoxicity when treated with GTE concentrations of around 10 µg/mL (a maximum of 50 and a minimum of 0.01 µg/mL). Another study, testing EGCG, demonstrated no toxic effect at 10 µg/mL [Lee et al, 2009b], and whilst higher concentrations are occasionally tested, exposure times are generally shorter.…”