Is black tea consumption associated with a lower risk of cardiovascular disease and type 2 diabetes?

Tea and its phytochemicals: Hidden health benefits & modulation of signaling cascade by phytochemicals

Tea, one of the most widely consumed beverages, is prepared from the leaves of the Camellia sinensis. The promising health recompenses of tea have been linked to its different phenolic components, which have diverse biological characteristics. Tea also contains several flavonoids, alkaloids, phenolic, theanine, etc., which are associated with anti-oxidant characteristics and a variety of health benefits. It can also lower the pervasiveness of neurological disorders as well as prevent different types of cancer, metabolic syndromes, cardiovascular diseases, urinary stone, obesity, type 2 diabetes. Keeping in mind that tea helps to improve health and prevents many diseases, its consumption has been regarded as a "health-promoting habit" and current medical investigators have established the scientific basis for this concept over time. The current review provides new updated information and perspectives on the tea phytochemicals and their overall health benefits based on molecular processes, experimental studies, and clinical trials.

Theaflavin alleviates oxidative injury and atherosclerosis progress via activating microRNA-24-mediated Nrf2/HO-1 signal

Theaflavin (TF) in black tea has been shown to have significant antioxidant and anti-inflammatory capacity; however, the effects and the underlying mechanism of TF on atherosclerosis (AS) remain unclear. Herein, we investigated the effects and the potential mechanism of TF on AS progression in vivo and in vitro. ApoE^-/- mice were administrated with high fat diet (HFD) or HFD + TF (5 or 10 mg, i.g.) for 12 weeks. The results indicated that TF administration effectively decreases the serum lipid levels and the production of MDA in HFD-fed mice. Meanwhile, TF promotes the activities of antioxidant enzymes (SOD, CAT, and GSH-Px) and inhibits the formation of atherosclerotic plaque and the process of histological alterations in the aorta. In vitro, TF pretreatment could protect against cholesterol-induced oxidative injuries in HUVEC cells, decreasing the level of ROS and MDA, maintaining the activities of antioxidant enzymes. Further study revealed that TF upregulates Nrf2/HO-1 signaling pathway in vascular endothelial cells. Moreover, TF increases the level of microRNA-24 (miR-24), and miR-24 inhibition markedly compromises TF-induced Nrf2 activation and protective effects. In conclusion, the present study indicated that theaflavins may achieve the anti-atherosclerotic effect via activating miR-24-mediated Nrf2/HO-1 signaling pathway.

Diet and self-rated health among oldest-old Chinese

INTRODUCTION

Dietary behavior is a central modifiable risk factor for human health. This study examined the longitudinal relationship between dietary habits and self-rated health among the oldest-old Chinese.

METHODS

Participants aged 80 years and above (N = 7273) were first interviewed in 1998 and followed in subsequent waves 2-3 years apart till 2011-2012 in the Chinese Longitudinal Healthy Longevity Survey. Cox proportional hazards regressions were performed to estimate the effects of dietary habits on poor self-rated health, adjusting for various individual characteristics.

RESULTS

Compared to those who rarely/never consumed fruit, vegetable, meat, egg, and soybean-derived product, participants consuming such products almost every day were 28%, 20%, 32%, 16%, and 16% less likely to report poor self-rated health during follow-up, respectively. Compared to those who rarely/never consumed fruit, meat, fish, soybean-derived product, and tea, participants consuming such products occasionally were 12%, 24%, 11%, 15%, and 14% less likely to report poor self-rated health during follow-up, respectively. Compared to those who rarely/never consumed sugar, participants consuming sugar almost every day were 14% more likely to report poor self-rated health during follow-up. The effects of dietary habits on self-rated health to some extent differed by sex.

CONCLUSIONS

Oldest-old Chinese could gain health benefit from regular consumption of fruit, vegetable, meat, fish, egg, soybean-derived product, and tea; whereas their sugar consumption may need to be reduced. Future research is warranted to establish the recommended daily nutrient allowances for the oldest-old adults and better address the nutritional needs of this vulnerable population.

Tea and flavonoids: where we are, where to go next

There is a need to evaluate the evidence about the health effects of tea flavonoids and to provide valid, specific, and actionable tea consumption information to consumers. Emerging evidence suggests that the flavonoids in tea may be associated with beneficial health outcomes, whereas the benefits and risks of tea extracts and supplements are less well known. The next steps in developing tea science should include a focus on the most promising leads, such as reducing the risk of cardiovascular disease and stroke, rather than pursuing smaller, more diffuse studies of many different health outcomes. Future tea research should also include the use of common reference standards, better characterization of intervention products, and application of batteries of biomarkers of intakes and outcomes across studies, which will allow a common body of evidence to be developed. Mechanistic studies should determine which tea bioactive constituents have effects, whether they act alone or in combination, and how they influence health. Clinical studies should use well-characterized test products, better descriptions of baseline diets, and validated biomarkers of intake and disease risk reduction. There should be more attention to careful safety monitoring and adverse event reporting. Epidemiologic investigations should be of sufficient size and duration to detect small effects, involve populations most likely to benefit, use more complete tea exposure assessment, and include both intermediary markers of risk as well as morbidity and mortality outcomes. The construction of a strong foundation of scientific evidence on tea and health outcomes is essential for developing more specific and actionable messages on tea for consumers.