Tea is one of the most popular drinks not only for its attractive aroma and unique taste, but because it is believed that the substances contained in it promote good health. Since 3000 B.C. the Chinese people used the tea as a remedy because of its effective pharmaceutical activity. In recent years, particular attention has been given to white tea and the polyphenols found in it by the scientific community.
White tea includes only buds and the first leaves of the plant. The history of white tea begins in the northeast of China\'s Fujian province, and despite the modern use of machinery, production is often performed in traditional ways. The White Tea category strictly collects the youngest leaves - rich in nutritional value - and processes them with the most minimal procedure. The buds and the leaves wither in natural sunlight and then the drying process is followed.
After years of systematic research, white tea has many health benefits due to its high percentage of polyphenols, flavonoids and amino acids.
Research findings suggest that regular consumption of white tea can help reduce oxidative stress associated with a host of diseases such as obesity, inflammation, premature aging, Alzheimer\'s disease, Parkinson\'s disease, chronic polyarthritis, skin diseases, cataracts and brain damages. Of particular interest are the antioxidants which have plant origin and found in tea, especially catechins, which have been found to have protective properties in biological mechanisms of action that exhibit neurotoxicity.
Today, there is so many, even doctors, support the contribution of white tea to the prevention and reduction of the risk of many diseases.
In industrialized countries, the rising incidence in obesity-associated disorders, including cardiovascular disease and diabetes, has led to extensive study of the cellular, molecular processes involved in fat metabolism, as well as in natural lipolytic substances, such as polyphenols and methyloxanthines found in tea.
Finally, white tea help us to lose weight?
In the scientific literature, it is a subject of ongoing debate whether polyphenols and /or xanthines can be utilized to modulate different levels/phases of the adipocyte life cycle.
The findings indicate in a study published in Nutrition & Metabolism (2009) by scientists from Research & Development, Research Special Skincare (Hamburg, Germany), such as Sӧhle et al, that white tea extracts exhibit lipolytic activity and inhibit adipogenesis (formation of preadipocytes to mature adipocytes – development adipose tissue) in human subcutaneous early adipocytes.
Experiments with primary human cells have shown that incubation with a white tea extract solution reduces the accumulation of triglycerides during the adipogenesis process without affecting cell viability.
Samples treated with white tea extract solution dose-dependently exhibited significantly decreased triglyceride levels by up to 70% compared to the control group (samples without the addition of white tea).
In addition, a viability assay was used to determine whether the white tea extract solution could have adverse effects on cell viability. The cell populations cultivated with the presence of white tea extract solution showed a comparable esterase activity compared to the control group, which demonstrates that cell viability is not affected by the addition of the white tea extract.
To characterize the question whether white tea extract stimulates lipolytic activity, cultured adipocytes incubated with 2% white tea extract solution showed a significant increase in the free glycerol content (32 µg / ml) as compared to the control lipocytes at 20 µg / ml. The possible explanation for the observed attenuation in triglyceride incorporation during adipogenesis is the ability of white tea to increase the conversion of triglyceride to fatty acids and glycerol.
All of the above results, however, were exclusively obtained from isolated cells from utilized primary cultured human cells. Many studies have been conducted on polyphenols and their lipolytic activity, although most report results in murine 3T3-L1 cells. Although this mouse cell line represents a good model system to study fat metabolism, human cells should better reflect all the metabolic processes and the in vivo situation.
However, in order to investigate in more detail the lipolytic activity of white tea, the gene expression of essential transcription factors related to adipogenesis was analyzed by qRT-PCR (Real Time - Polymerase Chain Reaction) and the transcription factor ADD1 / SREBP- 1c (Adipocyte Determination and Differentiation / Sterol Regulatory Binding Protein) at the protein level by immunofluorescence analysis.
Since the experiments in the study show a decrease in the formation and accumulation of triglycerides, further investigation at the molecular events shows in more detail the effects of the action of white tea on cellular differentiation (adipogenesis). The transcription factor ADD1 / SREBP-1c is highly expressed in adipose tissue and plays an important role in adipocyte differentiation. Interestingly, stimulation of the white tea extract in the samples decreased its gene expression. Interestingly, stimulation of the white tea extract in the samples decreased its gene expression. Compared to control cells, cells incubated with 0.5% white tea showed significantly reduced its protein expression of the ADD1 / SREBP-1c gene at 44%. The immunofluorescence analysis together with quantitative analysis clearly shows that white tea extract influences adipocyte differentiation.
The dominant regulator of adipogenesis PPARγ (peroxisome proliferator activated receptor), a hormone receptor whose site of action is referred to the cell nucleus and its expression has been shown to be sufficient to induce adipogenesis, was studied by quantitative RT-PCR and other transcription factors such as C / EBPα, C / EBPδ that activate PPARγ.
Cell lines were cultivated on the appropriate substrate with or without the presence of white tea extract solution (0.5%) showed significantly comparable results. Cells incubated with white tea extract solution display a decrease in mRNA levels of these transcription factors (PPARγ - 19%, ADD1 / SREBP-1c - 64%, C / EBPα - 5%, C / EBP / δ - 58%) compared to control cells (100%). Overall, the observed reduction of adipogenesis – related transcription factors led scientists to conclude that white tea extract solution acts in two ways, by increasing lipolysis and by inhibiting adipogenesis (formation of mature adipocytes).
The white tea extract solution incubated with the cell lines contain as a main component the epigallocatechin-3-gallate (EGCG), the most important catechin in tea. EGCG has been studied separately for its more precise biological activity. Cells cultured for seven days in appropriate differentiation medium with 50 µM EGCG showed reduced triglyceride levels at 33% compared to control group cells (100%).
Overall, the results of this study have shown that white tea extract solution significantly inhibits adipogenesis and stimulates lipolytic activity. That is why analysts concluded that the white tea extract is an ideal, natural source that shows blocking effects on obesity.