Effect of Black Tea Extract and Thearubigins on Osteoporosis in Rats and Osteoclast Formation in vitro

The potential application of fermented tea as a drink for regulating bone mass

Currently, there is evidence to suggest the benefits of drinking fermented tea for people with osteoporosis, and based on this, many studies have been conducted on the dosage, exact ingredients, mechanisms, and industrial applications of fermented tea for protecting against osteoporosis. A summary and analysis of studies on the regulation of bone mass by oolong tea, black tea, and their active ingredients (including 39 known catechin compounds) was conducted. It was found that the regulation of bone mass by fermented tea is backed by evidence from epidemiology, animal experiments, and cell experiments. The main active components of fermented tea are tea polyphenols, tea pigments, and trace amino acids. The specific mechanisms involved include regulating bone marrow mesenchymal stem cell osteogenesis, inhibiting osteoclast activity, promoting calcium and phosphorus absorption, reducing inflammation levels, regulating gut microbiota, regulating endocrine function, and inhibiting oxidative stress. In terms of its application, extraction, precipitation, biosynthesis and membrane separation method are mainly used to separate the active ingredients of anti osteoporosis from fermented tea. In conclusion, fermented tea has sufficient theoretical and practical support for regulating bone mass and preventing osteoporosis, and is suitable for development as a health supplement. At the same time, a large amount of epidemiological evidence is needed to prove the specific dosage of tea consumption.

Potential mechanism of tea for treating osteoporosis, osteoarthritis, and rheumatoid arthritis

Osteoporosis (OP), osteoarthritis (OA), and rheumatoid arthritis (RA) are common bone and joint diseases with a high incidence and long duration. Thus, these conditions can affect the lives of middle-aged and elderly people. Tea drinking is a traditional lifestyle in China, and the long-term intake of tea and its active ingredients is beneficial to human health. However, the mechanisms of action of tea and its active ingredients against OP, OA, and RA are not completely elucidated. This study aimed to assess the therapeutic role and related mechanisms of tea and its active ingredients in OP, OA, and RA. Moreover, it expanded the potential mechanisms of tea efficacy based on network pharmacology and molecular docking. Results showed that tea has potential anti-COX properties and hormone-like effects. Compared with a single component, different tea components synergize or antagonize each other, thereby resulting in a more evident dual effect. In conclusion, tea has great potential in the medical and healthcare fields. Nevertheless, further research on the composition, proportion, and synergistic mechanism of several tea components should be performed.

A systematic review of tea pigments: Prevention of major diseases, protection of organs, and potential mechanisms and applications

With the growing awareness of a healthy life, tea pigments (TPGs) are in focus for their health benefits. TPGs not only provide specific color to tea liquor but also possess health benefits such as anti-obesity, anti-tumor, anti-inflammatory, anti-viral, anti-oxidative, and bacteriostatic properties. Also, TPGs can benefit bone, liver, kidney, cardiovascular, gut microbiome, and sleep health. Based on previous reports, this review provides a brief introduction to the health benefits of TPGs, focusing on the prevention of human diseases and the protection of organs. Also, the latest research on the functional mechanism(s), practical application, and development strategies of TPGs is discussed.

Tea consumption and the risks of osteoporosis and hip fracture: a population-based longitudinal follow-up study

This population-based longitudinal follow-up study showed a protective effect of tea consumption against osteoporosis, particularly among women and middle-aged people. High tea consumption was also associated with a reduced risk of hip fracture.

INTRODUCTION

To investigate the association of tea consumption with the risks of osteoporosis and hip fracture.

METHODS

This study used the Keelung Community-based Integrated Screening database and Taiwan's National Health Insurance Research Database. A total of 42,742 subjects aged 45 to 74 years were enrolled. Each was classified as no tea consumption, low tea consumption, and high tea consumption, according to the results of an eating habits questionnaire. The diagnosis of osteoporosis and hip fracture was based on BMD measured by dual-energy X-ray absorptiometry and the X-ray findings. The median follow-up time was 8.5 years.

RESULTS

As compared with the no tea consumption group, the osteoporosis HRs for the low tea consumption and high tea consumption groups were 0.88 (95% confidence interval (CI) 0.80-0.96) and 0.87 (95% CI 0.80-0.94), respectively. Among those participants aged 59 or below, the osteoporosis HRs for low tea consumption and high tea consumption (vs. no tea consumption) were 0.85 (95% CI 0.74-0.96) and 0.79 (95% CI 0.69-0.90). The HRs of hip fracture for the low tea consumption and high tea consumption groups (vs. no tea consumption) were 0.85 (95% CI 0.67-1.08) and 0.69 (95% CI 0.55-0.86), respectively.

CONCLUSION

Tea consumption was linked to a lower risk of osteoporosis, particularly among women and middle-aged people. High tea consumption was also associated with a reduced risk of hip fracture.

Gut Microbiota as a Novel Tool to Dissect the Complex Structures of Black Tea Polymers

Thearubigins, polymers of tea catechins, account for more than 20% of the black tea polyphenols and have been reported to be the active components in black tea. However, the chemical structures and underlying mechanisms regarding how the thearubigins, being poorly bioavailable, generate in vivo health benefits are still largely unknown. Using germ-free and specific pathogen-free husbandry conditions combined with LC/MS-based nontargeted and targeted metabolomic analyses, we investigated the role of intestinal bacteria in thearubigin metabolism. Theaflavins and theasinensins were identified as the major microbial metabolites of thearubigins, suggesting that these molecules are the building units for the complex thearubigins. To further confirm this, thearubigin depolymerization was done using menthofuran in an acidic condition. Menthofuran-conjugated theaflavins, theasinensins, and catechins as well as their free forms were detected as the major degradation products of thearubigins. This indicated that theaflavins and theasinensins could be further polymerized through B-type proanthocyanidin linkages. Furthermore, four microbial degradation products were able to be detected in urine samples, suggesting that they can be absorbed into the circulatory system. Using the combination of microbial degradation, metabolomics, and chemical degradation, our results demonstrate that thearubigins are the complex polymers of theaflavins, theasinensins, and catechins and can be metabolized by gut microbiota to their corresponding bioactive and bioavailable smaller molecular metabolites.

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

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 μg/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-2-yl]-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.

Research progress of black tea thearubigins: a review

As the most abundant component in black tea, thearubigins (TRs) contribute a lot to black tea's characteristic color, mouthfeel, and potential health benefits. But compared to lower molecular weight black tea polyphenols, there are fewer researches that focus on TRs because of their heterogeneity. This review summarized recent research progress on (1) isolation method of TRs; (2) structure analysis and formation mechanism of TRs; (3) biofunctions of TRs, including antioxidation, antimutagenic and anticancer effects, effects on mitochondrial activation, gastrointestinal motility and skeletal health, to show some future research aspects and prospects of TRs.

Red Rooibos Tea Stimulates Osteoblast Mineralization in a Dose-Dependent Manner

Most studies show a positive association between higher tea intake and bone mineral density (BMD), while associations with fracture are inconclusive. Although a few studies have investigated the potential effects of rooibos tea on the bone cell metabolism, only 1 or 2 doses were tested or specific flavonoids were evaluated in isolation. A dose-response study is needed to comprehensively identify whether a level that modulates bone cell activity is associated with dietary or supplemental levels of red rooibos (RR) tea. We investigated if RR tea stimulates mineralization in a dose-dependent manner. Mineralization was induced in Saos-2 cells in the presence of RR tea (0.1–10 µg/mL of polyphenols) or control (dH2O) for 5 days. Cell activity, mRNA, protein expression and activity of key regulators of mineralization were measured. A positive dose-dependent relationship was observed between RR tea concentration and mineralization accompanied with similar trends in cell activity. With high concentrations of tea, protein expression of enzymes directly regulating mineralization (ALP and NPP1) were unchanged but ALP activity was significantly elevated. Osteopontin (OPN) was significantly downregulated midway through mineralization while sclerostin (SOST) was upregulated in response to higher concentrations of RR tea. In conclusion, RR tea stimulated osteoblast mineralization in a dose-dependent manner and were accompanied with downregulation of OPN, increased ALP activity, and increased cell activity.

Overview of Molecular Mechanisms Involved in Herbal Compounds for Inhibiting Osteoclastogenesis from Macrophage Linage RAW264.7

Differentiation from RAW264.7 cells to osteoclasts rely on many signaling pathways, such as NF-κB, MAPK, Akt and others. However, the specific underlying mechanisms are not clear. Recently, much works have focused on the inhibitory effects of plant derived compounds in the differentiation from RAW264.7 to osteoclasts. However, the specific mechanisms remain unclear. In this paper, we summarize a lot of plant derived compounds which exert blocking effect on the progression of differentiation via signaling pathways.