Non-tea Drinkers Research Articles

Protective effect of green tea against prostate cancer: a case-control study in southeast China.

To investigate whether green tea consumption has an etiological association with prostate cancer, a case-control study was conducted in Hangzhou, southeast China during 2001-2002. The cases were 130 incident patients with histologically confirmed adenocarcinoma of the prostate. The controls were 274 hospital inpatients without prostate cancer or any other malignant diseases, and matched to the age of cases. Information on duration, quantity and frequency of usual tea consumption, as well as the number of new batches brewed per day, were collected by face-to-face interview using a structured questionnaire. The risk of prostate cancer for tea consumption was assessed using multivariate logistic regression adjusting for age, locality, education, income, body mass index, physical activity, alcohol consumption, tobacco smoking, total fat intake, marital status, age at marriage, number of children, history of vasectomy and family history of prostate cancer. Among the cases, 55.4% were tea drinkers compared to 79.9% for the controls. Almost all the tea consumed was green tea. The prostate cancer risk declined with increasing frequency, duration and quantity of green tea consumption. The adjusted odds ratio (OR), relative to non-tea drinkers, were 0.28 (95% CI = 0.17-0.47) for tea drinking, 0.12 (95% CI = 0.06-0.26) for drinking tea over 40 years, 0.09 (95% CI = 0.04-0.21) for those consuming more than 1.5 kg of tea leaves yearly, and 0.27 (95% CI = 0.15-0.48) for those drinking more than 3 cups (1 litre) daily. The dose response relationships were also significant, suggesting that green tea is protective against prostate cancer.

Tea Consumption and the Prevalence of Coronary Heart Disease in Saudi Adults: Results from A Saudi National Study

Background. The aim of the study was to determine whether there was a relationship between tea consumption and the prevalence of coronary heart disease (CHD) in Saudi Arabia. Methods. The relationship between tea consumption and the prevalence of CHD was investigated using multiple logistic regression analysis in the Saudi Coronary Artery Disease Study. A total of 3,430 men and women aged 30–70 years was studied. Results. Of the 3,430 subjects who were assigned a category, 6.3% were classified as having indications of CHD. Those who did drink more than 6 cups of tea (>480 mL) per day had a significantly lower prevalence of CHD than the nontea drinkers ( P < 0.001). Adjustments for risk factors including age, gender, occupation, education, smoking, family history, blood lipids, diabetes, blood pressure, BMI, physical activity, and coffee and fat intake did not remove the significance (OR = 0.49; 95% CI = 0.24–0.96). There was a positive dose-response effect between tea consumption and CHD ( P < 0.001) that was persistent after adjustment for various risk factors ( P = 0.022). Conclusions. These findings support a potential protective effect of tea consumption in relation to CHD in this Saudi study in which all tea consumed was black tea.

Inverse association of tea and flavonoid intakes with incident myocardial infarction: the Rotterdam Study

Dietary flavonoids may protect against cardiovascular disease, but evidence is still conflicting. Tea is the major source of flavonoids in Western populations. The association of tea and flavonoid intake with incident myocardial infarction was examined in the general Dutch population. A longitudinal analysis was performed with the use of data from the Rotterdam Study-a population-based study of men and women aged >or=55 y. Diet was assessed at baseline (1990-1993) with a validated semiquantitative food-frequency questionnaire. The analysis included 4807 subjects with no history of myocardial infarction, who were followed until 31 December 1997. Data were analyzed in a Cox regression model, with adjustment for age, sex, body mass index, smoking status, pack-years of cigarette smoking, education level, and daily intakes of alcohol, coffee, polyunsaturated fat, saturated fat, fiber, vitamin E, and total energy. During 5.6 y of follow-up, a total of 146 first myocardial infarctions occurred, 30 of which were fatal. The relative risk (RR) of incident myocardial infarction was lower in tea drinkers with a daily intake >375 mL (RR: 0.57; 95% CI: 0.33, 0.98) than in nontea drinkers. The inverse association with tea drinking was stronger for fatal events (0.30; 0.09, 0.94) than for nonfatal events (0.68; 0.37, 1.26). The intake of dietary flavonoids (quercetin + kaempferol + myricetin) was significantly inversely associated only with fatal myocardial infarction (0.35; 0.13, 0.98) in upper compared with lower tertiles of intake. An increased intake of tea and flavonoids may contribute to the primary prevention of ischemic heart disease.

Tea drinking and bone mineral density in older women

High caffeine intake is reportedly a risk factor for reduced bone mineral density (BMD) in women. Most studies, however, are from populations in which coffee drinking predominates and is the major caffeine source. Tea contains caffeine but also has other nutrients, such as flavonoids, that may influence bone mass in different ways. We examined the relation between tea drinking and BMD in older women in Britain, where tea drinking is common. We measured BMD at the lumbar spine, femoral neck, greater trochanter, and Ward's triangle in 1256 free-living women aged 65-76 y in Cambridge, United Kingdom. Tea drinking was assessed by self-completed questionnaire and women were categorized as tea drinkers or non-tea drinkers. There were 1134 tea drinkers (90.3%) and 122 non-tea drinkers (9.7%). Compared with non-tea drinkers, tea drinkers had significantly greater ( approximately 5%) mean BMD measurements, adjusted for age and body mass index, at the lumbar spine (0.033 g/cm(2); P = 0.03), greater trochanter (0.028 g/cm(2); P = 0.004), and Ward's triangle (0.025 g/cm(2); P = 0.02). Differences at the femoral neck (0.013 g/cm(2)) were not significant. These findings were independent of smoking status, use of hormone replacement therapy, coffee drinking, and whether milk was added to tea. Older women who drank tea had higher BMD measurements than did those who did not drink tea. Nutrients found in tea, such as flavonoids, may influence BMD. Tea drinking may protect against osteoporosis in older women.

Tea consumption: fluid intake and bladder cancer risk in southern Taiwan

Objectives. To determine whether tea consumption and intake of other beverages increases bladder cancer risk. Methods. A case-control study was conducted in Kaohsiung, Taiwan between August 1996 and June 1997. Index patients studied were consecutive patients with histologically confirmed, newly diagnosed bladder cancer in two major hospitals. For each patient, 4 controls were selected from patients with non-neoplastic and nonurologic diseases undergoing surgical operations in the same hospital and individually matched by sex, age, and date of admission. Using a structured questionnaire, a trained interviewer interviewed 40 patients and 160 controls. Conditional logistic regression analysis adjusting for ethnicity, family history, and smoking status and matching variables were used to estimate the odds ratio (OR) and 95% confidence interval (CI). Results. Tea consumption overall was associated with increased bladder cancer risk (OR 3.29, 95% CI 1.34 to 8.05). Compared with non-tea drinkers, the odds ratios of bladder cancer for oolong tea drinkers was 3.00 (95% CI 1.20 to 7.47); for non-oolong tea drinkers (black and/or other green tea), it was 14.86 (95% CI 2.13 to 103.83). The risk was greater among those who began to drink tea before age 40 (OR 9.50, 95% CI 2.39 to 37.75) and those who had been drinking tea for more than 30 years (OR 17.75, 95% CI 3.00 to 105.17). Coffee, tap water, and alcohol consumption were associated with a slightly increased risk, and both soy juice and rice juice consumption were associated with reduced risk; none of these odds ratio estimates were statistically significant, however. Conclusions. Our results suggest that tea consumption is associated with an increased risk of bladder cancer.

Tea drinking and microcytic anemia in infants

To evaluate the effect of tea drinking on the occurrence of microcytic anemia in infants, we studied 122 healthy infants who underwent routine blood counts at the age of 6-12 months. An overall high frequency of anemia (Hb less than 11 gm/dl-48.4%), microcytosis (MCV less than 70 Mm3-21.3%) and microcytic anemia (19%) was found in the whole group. The percentage of tea drinking infants with microcytic anemia (32.6%) was significantly higher than that of the non-tea drinkers (3.5%). The daily amount of tea drinking was 50-750 ml (median 250 ml). The tea drinkers had significantly lower mean levels of hemoglobin than that of the non-tea drinkers (10.5 +/- 1.2 gm/dl vs 11.2 +/- 0.8 gm/dl, respectively) and significantly lower mean levels of mean corpuscular volume than that of the non-tea drinkers (71.5 +/- 7.1 micron 3 vs 76.1 +/- 4.6 micron 3). There were no significant differences between the two groups in their sex distribution and in the duration of breast feeding. The two groups differed with regard to their ages and social class but a multivariate analysis had excluded the possible confounding effect of these differences on the hematological results. Based on our finding we do not recommend giving tea to infants whose main source of iron is from milk, grains, vegetables or medicinal sources.