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Meta-analyses of studies conducted among Western populations suggest that coffee consumption does not affect osteoporotic fracture risk. However, experimental studies have shown that the effect of caffeine on bone health may depend on dosage. We examined the associations between consumption of coffee, tea and caffeine and risk of hip fracture in an Asian cohort. In a population-based prospective cohort of 63,257 Chinese men and women aged 45-74 years in Singapore, a validated semi-quantitative food frequency questionnaire was used to assess habitual consumption of coffee and tea at baseline. Cox proportional hazards regression models were used to estimate hazard ratio (HR) and 95% confidence interval (CI) for risk of hip fracture with adjustment for potential confounders. During a mean follow-up of 16.7 years, 2502 incident hip fracture cases were identified. Compared to coffee drinkers <1 cup/week, those who drank ≥4 cups/day had a statistically significant higher risk to develop hip fractures, the HR (95% CI) was 1.32 (1.07, 1.63) in the whole cohort analysis, 1.46 (1.01, 2.10) for men and 1.33 (1.02, 1.72) for women. Among postmenopausal women, compared to those who drank coffee <1 cup/week, drinking 2-3 cups/day was associated with the lowest risk [HR: 0.88 (0.76, 1.01)] and drinking ≥4 cups/day was associated with the highest risk [HR: 1.31 (1.00, 1.71)]. Similar associations with caffeine intake were found among postmenopausal women. Restricted spline analyses suggested a non-linear association between coffee/caffeine consumption and hip fracture risk in postmenopausal women (p for non-linearity ≤ 0.05). No association was found with tea consumption in either sex. These data suggest that drinking coffee ≥4 cups/day is associated with a higher hip fracture risk, while a moderate intake may alleviate risk in postmenopausal women. Future studies should corroborate these results to determine levels of optimal coffee consumption in relation to bone health.

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INTRODUCTION: Heavy alcohol consumption increases the risk of active tuberculosis (TB). However, the relation between lower levels of alcohol intake and TB risk remains unclear. We aimed to evaluate the association between alcohol intake and risk of active TB and assess whether the associations were modified by smoking status, which is another risk factor for active TB. METHODS: The Singapore Chinese Health Study is a prospective cohort of 63 257 adults aged 45-74 years recruited from 1993 to 1998. Information on alcohol intake and smoking history was collected at recruitment. Active TB cases were identified via linkage with National TB Notification Registry. RESULTS: During a mean follow-up of 16.8 years, 1249 incident cases of active TB were identified. Among non-smokers, compared with total abstinence, participants who had monthly to weekly intake of alcohol had reduced TB risk (HR 0.70, 95% CI 0.55 to 0.89), but this reduction in risk with low-dose drinking was not observed among current smokers (HR 0.96, 95% CI 0.77 to 1.18; p for interaction=0.02). Comparatively, drinking 2+ drinks daily was associated with increased TB risk among current smokers (HR 1.51, 95% CI 1.11 to 2.05). This increased risk was not observed among non-smokers (HR 0.93, 95% CI 0.49 to 1.77) and the interaction between alcohol intake and smoking status was of borderline significance (p for interaction=0.08). In joint effect, compared with those who neither smoked nor drank, the risk of active TB increased from 1.82 (95% CI 1.57 to 2.10) in current smokers who were non-drinkers to 3.16 (95% CI 2.35 to 4.24) in current smokers who also drank 2+ drinks daily. CONCLUSION: While low intake of alcohol may protect against active TB among non-smokers, drinking 2+ drinks daily could act synergistically with smoking to increase the risk of active TB in current smokers.

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Experimental studies showed that tea polyphenols may inhibit growth of Mycobacterium tuberculosis. However, no prospective epidemiologic study has investigated tea drinking and the risk of active tuberculosis. We investigated this association in the Singapore Chinese Health Study, a prospective population-based cohort of 63,257 Chinese aged 45-74 years recruited between 1993 and 1998 in Singapore. Information on habitual drinking of tea (including black and green tea) and coffee was collected via structured questionnaires. Incident cases of active tuberculosis were identified via linkage with the nationwide tuberculosis registry up to 31 December 2014. Cox proportional hazard models were used to estimate the relation of tea and coffee consumption with tuberculosis risk. Over a mean 16.8 years of follow-up, we identified 1249 incident cases of active tuberculosis. Drinking either black or green tea was associated with a dose-dependent reduction in tuberculosis risk. Compared to non-drinkers, the hazard ratio (HR) (95% confidence interval (CI)) was 1.01 (0.85-1.21) in monthly tea drinkers, 0.84 (0.73-0.98) in weekly drinkers, and 0.82 (0.71-0.96) in daily drinkers (p for trend = 0.003). Coffee or caffeine intake was not significantly associated with tuberculosis risk. In conclusion, regular tea drinking was associated with a reduced risk of active tuberculosis.

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