Black and Green Tea as Well as Specialty Teas Increase Osteoblast Mineralization with Varying Effectiveness

Abstract

Many human studies suggest a benefit of tea consumption on bone health. The study objective was to compare the ability of different tea types to promote mineralization. Saos-2 cells underwent mineralization (5 days) in the presence of tea (white: WT, green: GT, black: BT, green rooibos: GR, or red rooibos: RR; 1 lg/mL of polyphenols) or control. Total polyphenol content (TPC, Folin-Ciocalteu's reagent), antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl [DPPH] scavenging), mineralization (Alizarin Red staining), gene expression quantitative reverse transcription PCR (RT-qPCR), and cell activity (3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide assay) were determined. TPC was highest in GT and BT. The ability of each tea to inhibit DPPH also differed (WT, GT > RR) after normalizing for polyphenol quantity. Each tea increased mineralization and differences were observed among types (GT/BT/GR/RR > WT, GT = BT = GR, RR > BT/GT). mRNA expression of alkaline phosphatase (ALP) and ectonucleotide pyrophosphatase/phosphodiesterase (NPP1) remained unchanged, whereas osteopontin (OPN) and sclerostin (SOST) were reduced in cells treated with tea, regardless of type. At 24-and 48-h postexposure to tea, cell activity was greater in cells receiving any of the teas compared with vehicle control. Supplementation increased mineralization regardless of tea type with both rooibos teas and black tea stimulating greater mineralization than WT, whereas green tea is similar to the others. While future study is needed to confirm in vivo effects, the results suggest that consuming any of the teas studied may benefit bone health.

Green and white teas as health-promoting foods

“…25 EGCG can also improve the osteogenic differentiation of mesenchymal stem cells in the bone marrow. 68 Overall, this study demonstrated for the first time that local treatment of EGCG can accelerate the fracture healing process, at least in part, via bone morphogenetic protein-2 (BMP-2). 68 Green tea constituents such as catechins, theaflavins, kaempferol and phenolic acids have been seen to have estrogenic effects, which can influence bone health.…”

“…68 Overall, this study demonstrated for the first time that local treatment of EGCG can accelerate the fracture healing process, at least in part, via bone morphogenetic protein-2 (BMP-2). 68 Green tea constituents such as catechins, theaflavins, kaempferol and phenolic acids have been seen to have estrogenic effects, which can influence bone health. 69 Finally, lead (Pb) and cadmium (Cd) are environmentally toxic metals.…”

“…Several are the studies that describe the beneficial effects of different varieties of tea on bone health. 25,[66][67][68][69] According to Tomaszewska et al a reduction in the risk of hip fractures was described in regular tea drinkers. 66 In the same study, a better bone mineral density was achieved by post-menopausal women who drank tea.…”

Pregnancy and Lactation in Sprague-Dawley Rats Result in Permanent Reductions of Tibia Trabecular Bone Mineral Density and Structure but Consumption of Red Rooibos Herbal Tea Supports the Partial Recovery

“…Several nutrients, including calcium and vitamin D, as well as various foods and food components have been studied for their bone promoting or supporting effects (10)(11)(12)(13). Tea and its polyphenols-including some herbal teas such as red rooibos (RR)-may promote bone health and mineral production (14)(15)(16)(17). Several epidemiological studies in different countries including Australia, Britain, and Taiwan have also identified positive associations between black or green tea consumption and greater BMD later in life (18)(19)(20).…”

“…To date, RR tea has not been studied in vivo for potential bone promoting or supporting effects. Also, in vitro, a wide variety of teas derived from Camellia sinensis and herbal teas from other plants such as RR have been shown to increase osteoblast activity and proliferation (16,17); while also having the capacity to decrease osteoclast activity and proliferation (21,22)-possibly by acting as antioxidants and thereby reducing reactive oxygen species (ROS). ROS have been shown to suppress mineralization and increase resorption in vitro (23)(24)(25).…”