Antioxidants of the Beverage Tea in Promotion of Human Health

Siddiqui, Imtiaz A.; Afaq, Farrukh; Adhami, Vaqar M.; Ahmad, Nihal; Mukhtar, Hasan

doi:10.1089/152308604773934323

Cited by 113 publications

(89 citation statements)

References 84 publications

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“…Among them, oolong tea has been studied for its antihypertensive effect (Yang and Koo, 2000), antioxidant properties (Kuroda and Hara, 1999;Siddiqui et al, 2004), effect on reduction of cardiovascular disease risk (Yang and Koo, 1997) and antiobesitic properties (Han et al, 1999;Rumpler et al, 2001;Komatsu et al, 2003). We have previously shown that oolong tea has antihyperglycemic effect .…”

Section: Introductionmentioning

confidence: 99%

Polyphenol-enriched oolong tea increases fecal lipid excretion

Kusumoto

Abe

et al. 2006

Eur J Clin Nutr

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Objective: To assess possibility of polyphenol-enriched oolong tea to reduce dietary lipid absorption in humans. Design: Twelve healthy adult subjects, three males and nine females, aged (mean7s.d.) 22.071.8 years, respectively, were randomly divided into two groups. The participants were followed a double-blind placebo-controlled crossover design, including 7-day washout periods and 10-day treatment periods. During the treatment periods, subjects were given about 38 g of lipids from potato chips (19 g each within 30 min after lunch and dinner) and total 750 ml beverages (placebo-or polyphenolenriched oolong tea) at three meals. Blood samples were collected for biochemical examination at days 8, 18, 25 and 35 of the study period. On the last 3 days of each treatment period, feces were collected to measure the excretion of lipids. Results: Lipid excretion into feces was significantly higher in the polyphenol-enriched oolong tea period (19.3712.9 g/3day) than in the placebo period (9.477.3 g/3day) (Po0.01). Cholesterol excretion tended to increase in polyphenol-enriched oolong tea period (1.871.2 g/3day) compared with that of placebo (1.270.6 g/3day) (P ¼ 0.056). Conclusions:The results of this study indicated that polyphenol-enriched oolong tea could increase lipid excretion into feces when subjects took high-lipid diet.

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Section: Introductionmentioning

confidence: 99%

Polyphenol-enriched oolong tea increases fecal lipid excretion

Kusumoto

Abe

et al. 2006

Eur J Clin Nutr

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“…It has been postulated that tea polyphenols act in the gastrointestinal tract by modulating the composition of the gut microflora (Weisburger and Chung, 2002). A high content of clostridia and a low percentage of bifidobacteria have been observed in the intestinal microflora of patients with colon cancer (Siddiqui et al, 2004). Animal studies on green tea show that polyphenols selectively inhibit the growth of clostridia and promote bifidobacteria colonisation, leading to a drop in faecal pH (Yamamoto et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

Black tea – helpful or harmful? A review of the evidence

Ruxton²,

2006

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Objective: To consider whether consumption of black tea has a positive or negative impact on health. Design: Databases were searched for relevant epidemiological and clinical studies published between 1990 and 2004. Results: Clear evidence was found for coronary heart disease (CHD), where an intake of X3 cups per day related to risk reduction. The mechanism could involve the antioxidant action of tea polyphenols. While experimental models have suggested that flavonoids attenuated cancer risk, epidemiological studies failed to demonstrate a clear effect for tea, although there is moderate evidence for a slightly positive or no effect of black tea consumption on colorectal cancer. Studies on cancer were limited by sample sizes and insufficient control of confounders. There is moderate evidence suggestive of a positive effect of black tea consumption on bone mineral density although studies were few. There is little evidence to support the effect of tea on dental plaque inhibition but evidence to support the contribution of tea to fluoride intakes and thus theoretical protection against caries. There was no credible evidence that black tea (in amounts typically consumed) was harmful. Normal hydration was consistent with tea consumption when the caffeine content was o250 mg per cup. A moderate caffeine intake from tea appeared to improve mental performance, although sample sizes were small. There was no evidence that iron status could be harmed by tea drinking unless populations were already at risk from anaemia. Conclusions: There was sufficient evidence to show risk reduction for CHD at intakes of X3 cups per day and for improved antioxidant status at intakes of one to six cups per day. A maximum intake of eight cups per day would minimise any risk relating to excess caffeine consumption. Black tea generally had a positive effect on health. Sponsorship: The Tea Council. The authors confirm that the sponsors played no role in the writing of this review.

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“…Evidences collected from geographic, epidemiologic, and migration studies suggest that frequent consumption of green tea is associated with lower frequencies of prostate cancer in Asian populations in general compared with those in western societies [73][74][75][76][77]. Laboratory and preclinical animal studies also indicate a protective role of green tea against prostate cancer [78][79][80][81][82].…”

Section: Cancermentioning

confidence: 99%