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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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The Effect of a Multivitamin and Mineral Supplement on Immune Function in Healthy Older Adults: A Double-Blind, Randomized, Controlled Trial.
Fantacone, ML, Lowry, MB, Uesugi, SL, Michels, AJ, Choi, J, Leonard, SW, Gombart, SK, Gombart, JS, Bobe, G, Gombart, AF
Nutrients. 2020;12(8)
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Vitamins and minerals are essential for a healthy immune system. The prevalence of vitamin and mineral deficiencies increases with age, and this may contribute to age-related decline of the immune system. The aim of this study was to investigate whether a daily multivitamin and mineral (MVM) supplement could improve the immune function of older people. 42 healthy adults aged between 55 and 75 took part in this single-centre, two-armed, parallel, randomised, double-blinded study. Half of the group was given a MVM supplement called Redoxon Vita Immune (VI) containing the vitamins A, D, E, C, B6, B12 and folate plus iron, copper, zinc and selenium daily for 12 weeks, whilst the other half was given placebo tablets for 12 weeks. Participants were instructed to avoid certain foods high in vitamins and minerals such as oily fish, red meat, liver, and citrus fruits during the study period. Blood and saliva samples were taken from all participants at the beginning and end of the study period, to measure vitamin and mineral status and markers of immune function. Participants also kept a diary to record any illnesses or symptoms. At the end of the study, participants given the MVM supplement had increased their blood levels of vitamin C by 126% and zinc by 43%. There was no significant change in blood levels of vitamin D. There was no significant difference in the potential of blood to kill the introduced bacteria Staphylococcus aureus, or in neutrophil activity, nor were there any significant changes in blood levels of cytokines and chemokines. Participants taking the supplement did however report a shorter length, and lower severity of illnesses compared to those taking the placebo. The authors concluded that their findings support further research to test whether MVM supplementation can improve immune outcomes in older adults.
Abstract
Older adults are at increased risk for vitamin and mineral deficiencies that contribute to age-related immune system decline. Several lines of evidence suggest that taking a multi-vitamin and mineral supplement (MVM) could improve immune function in individuals 55 and older. To test this hypothesis, we provided healthy older adults with either an MVM supplement formulated to improve immune function (Redoxon® VI, Singapore) or an identical, inactive placebo control to take daily for 12 weeks. Prior to and after treatment, we measured (1) their blood mineral and vitamin status (i.e., vitamin C, zinc and vitamin D); (2) immune function (i.e., whole blood bacterial killing activity, neutrophil phagocytic activity, and reactive oxygen species production); (3) immune status (salivary IgA and plasma cytokine/chemokine levels); and (4) self-reported health status. MVM supplementation improved vitamin C and zinc status in blood and self-reported health-status without altering measures of immune function or status or vitamin D levels, suggesting that healthy older adults may benefit from MVM supplementation. Further development of functional assays and larger study populations should improve detection of specific changes in immune function after supplementation in healthy older adults. Clinical Trials Registration: ClinicalTrials.gov #NCT02876315.
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Influence of a montmorency cherry juice blend on indices of exercise-induced stress and upper respiratory tract symptoms following marathon running--a pilot investigation.
Dimitriou, L, Hill, JA, Jehnali, A, Dunbar, J, Brouner, J, McHugh, MP, Howatson, G
Journal of the International Society of Sports Nutrition. 2015;12:22
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Prolonged exercise, such as marathon running, is associated with upper respiratory tract (URT) symptoms and airway inflammation. Tart Montmorency cherry juice, high in phytochemicals such as anthocyanins and quercetin, has been shown to have anti-inflammatory and anti-oxidative properties and therefore may help reduce inflammation and oxidative stress triggered by exercise. In this pilot study, twenty marathon runners were randomly assigned to receive two servings a day of either a placebo drink or cherry juice for eight days ─ prior, during and after a marathon run. Any URT symptoms were reported, and inflammatory markers were measured pre- and post-race and 24 and 48 hrs after the race, from saliva (immunoglobulins and cortisol) and serum (C-reactive protein, CRP). No differences in the effect on immunoglobulins and cortisol were found between the two groups. The increase in CRP was significantly lower in the cherry juice group compared to the placebo group. 50% of the runners in the placebo group developed URT symptoms, while none were reported in the cherry juice group. The authors conclude that Montmorency cherry juice may protect the URT from inflammatory symptoms triggered by exercise. They propose further studies with larger sample size of participants, suffering from various inflammatory respiratory conditions.
Abstract
BACKGROUND Prolonged exercise, such as marathon running, has been associated with an increase in respiratory mucosal inflammation. The aim of this pilot study was to examine the effects of Montmorency cherry juice on markers of stress, immunity and inflammation following a Marathon. METHODS Twenty recreational Marathon runners consumed either cherry juice (CJ) or placebo (PL) before and after a Marathon race. Markers of mucosal immunity secretory immunoglobulin A (sIgA), immunoglobulin G (IgG), salivary cortisol, inflammation (CRP) and self-reported incidence and severity of upper respiratory tract symptoms (URTS) were measured before and following the race. RESULTS All variables except secretory IgA and IgG concentrations in saliva showed a significant time effect (P <0.01). Serum CRP showed a significant interaction and treatment effect (P < 0.01). The CRP increase at 24 and 48 h post-Marathon was lower (P < 0.01) in the CJ group compared to PL group. Mucosal immunity and salivary cortisol showed no interaction effect or treatment effect. The incidence and severity of URTS was significantly greater than baseline at 24 h and 48 h following the race in the PL group and was also greater than the CJ group (P < 0.05). No URTS were reported in the CJ group whereas 50 % of runners in the PL group reported URTS at 24 h and 48 h post-Marathon. CONCLUSIONS This is the first study that provides encouraging evidence of the potential role of Montmorency cherries in reducing the development of URTS post-Marathon possibly caused by exercise-induced hyperventilation trauma, and/or other infectious and non-infectious factors.