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The Effects of Black Tea Consumption on Intestinal Microflora-A Randomized Single-Blind Parallel-Group, Placebo-Controlled Study.
Tomioka, R, Tanaka, Y, Suzuki, M, Ebihara, S
Journal of nutritional science and vitaminology. 2023;69(5):326-339
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Tea from the leaves of the tea plant (Camelia sinensis) is consumed around the world. Tea has many health benefits, and in part, this is due to its rich content in compounds classed as polyphenols. Through the fermentation process, black tea is particularly high in polyphenols. Previous studies around respiratory infections indicated that regular consumption of black tea appeared to improve immune defence mechanisms that protect mucous membranes, called mucosal immunity. As this mucosal immunity is closely influenced by gut bacteria, the authors speculated whether the previously seen impact of improved mucosal immunity is related to the ability of black tea to also modulate bacteria in the gut. A previously run randomised single-blinded, placebo-controlled trial with 72 Japanese participants who consumed three cups of black tea (2g) or a placebo of barley tea for 12 weeks provided the data for this study. Data gathered included gut flora analysis, short-chain fatty acids (SCFAs) levels - fats that play a role in maintaining gut health, and saliva IgA (SIgA) concentrations - which are antibodies made in the lymph tissue of the gut. The results showed that black tea consumption led to a significant increase in the abundance of Prevotella bacteria, which mediate SCFA production and are involved in normalising immune function. Furthermore, tea increased butyrate-producing bacteria. Butyrate is associated with improved barrier function of the gut walls but also helps to manage pathogens and immune responses. Black tea consumption also increased salivary SIgA concentration - a type of antibody on the mucous membranes that prevents pathogens from entering the body -, and a decrease in stool acetic acid concentration, which may be due to the increase in butyrate-producing bacteria which use acetic acid to make butyrate. Notably, participants with low salivary SIgA levels at the start had a more pronounced positive change in total bacteria, after consuming black tea compared to the placebo group. The authors concluded that regular consumption of black tea may help to improve mucosal immunity by increasing the abundance of beneficial bacteria in the gut.
Abstract
We previously reported that black tea consumption for 12 wk reduced the risk of acute upper respiratory tract inflammation, and improved secretory capacity in individuals with low salivary SIgA levels (Tanaka Y et al. 2021. Jpn Pharmacol Ther 49: 273-288). These results suggested that habitual black tea consumption improves mucosal immunity. Therefore, in this study we evaluated the effect of black tea intake on gut microbiota, which is known to be involved in mucosal immunity, by analyzing the bacterial flora and the short-chain fatty acids (SCFAs) concentration of feces collected during the above clinical study. The clinical design was a randomized, single-blind, parallel-group, placebo-controlled study with 72 healthy Japanese adult males and females, who consumed three cups of black tea (Black Tea Polymerized Polyphenols 76.2 mg per day) or placebo per day for 12 wk. In all subjects intake of black tea significantly increased abundance of Prevotella and decreased fecal acetic acid concentration. Particularly in the subjects with low salivary SIgA levels, the change over time of total bacteria, Prevotella, and butyrate-producing bacteria, which are involved in normalizing immune function, were higher in the black tea group than in the placebo group. In subjects with low abundance of Flavonifractor plautii a butyrate-producing bacteria, black tea consumption significantly increased salivary SIgA concentration and the absolute number of Flavonifractor plautii. In conclusion, our results suggest that improvement of mucosal immunity via an increase in butyrate-producing bacteria in the gut may partly contribute to the suppressive effect of black tea consumption on acute upper respiratory tract inflammation observed in our previous report.
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Effects of fasting and preoperative feeding in children.
Yurtcu, M, Gunel, E, Sahin, TK, Sivrikaya, A
World journal of gastroenterology. 2009;15(39):4919-22
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Preoperative fasting is usually carried out to prevent the risk of vomiting during anaesthesia. The study investigated whether children should have a long period of fasting before surgery. Eight groups of 10 children (aged 1-10 years) with disorders of groin and scrotum were orally fed normal liquid food (NLF) or a high calorie diet (HCD) in 2 divided doses at 6 hour intervals, then fasted for 2, 3, 4 or 5 hours prior to surgery. Four groups had NLF and 4 groups had HCD. All children had their glucose, prealbumin and cortisol levels measured twice, just after the oral feeding and just before surgery. Once anaesthesia was sufficient and stable, gastric liquid was collected and measured. Patients with disease that could delay gastric emptying, had high acid production or were on medication were excluded from the trial. The researchers found that there was no significant difference in blood prealbumin levels in all groups. There was significant increase in blood cortisol in 4 groups when fasted (NLF-2h fasted, HCD-2h fasted, NLF-3h fasted and HCD-5h fasted). Stomach aid residue liquids were at tolerable levels of 1-2ml in all children. Anaesthesia was uneventful, with no coughing, laryngospasm or vomiting reported, and outcomes of surgery and wound healing were not affected. The authors noted that drinking clear liquids up to 2 hours before surgery was unlikely to substantially affect the volume of gastric fluids, and did not appear to increase the risk of vomiting in normal, healthy children. Glucose and insulin infusions appeared to minimise endocrine stress response and normalised post-op insulin sensitivity. Additionally, there may be a psychological benefit for children as irritability appeared to decrease prior to surgery. The study concluded that there was no need for fasting longer than 2 hours prior to inguinoscrotal region surgery.
Abstract
AIM: To investigate whether children should undergo surgery without a long period of fasting after feeding. METHODS Eighty children with inguinoscrotal disorders (aged 1-10 years) were studied prospectively. They were divided into eight groups that each contained 10 children who were fed normal liquid food (NLF) and a high-calorie diet (HCD) 2, 3, 4 and 5 h before surgery, in two doses at 6-h intervals. NLF was given to four groups and HCD to the other four. In all groups, glucose, prealbumin and cortisol levels in the blood were measured twice: just after oral feeding and just before the operation. After the establishment of adequate anesthesia, gastric residue liquid was measured with a syringe. RESULTS Blood glucose levels in all patients fed NLF and HCD were high, except in patients in the HCD-4 group. There was no significant difference in the blood prealbumin levels. There was a significant increase in the blood cortisol levels in the NLF-2 (14.4 +/- 5.7), HCD-2 (13.2 +/- 6.0), NLF-3 (10.9 +/- 6.4), and HCD-5 (6.8 +/- 5.7) groups (P < 0.05). CONCLUSION The stress of surgery may be tolerated by children when they are fed up to 2 h before elective surgery.