S C Larsson et al, 2015. Coffee consumption is not associated with increased risk of atrial fibrilation: results from two prospective cohorts and a meta-analysis, BMC Medicine, published online ahead of print.

Abstract

Background: Whether coffee consumption affects the risk of developing atrial fibrillation (AF) remains unclear. We sought to investigate the association between coffee consumption and incidence of AF in two prospective cohorts, and to summarize available evidence using a meta-analysis.

Methods: Our study population comprised 41,881 men in the Cohort of Swedish Men and 34,594 women in the Swedish Mammography Cohort who had provided information on coffee consumption in 1997 and were followed up for 12 years. Incident cases of AF were ascertained by linkage with the Swedish Hospital Discharge Register. For the meta-analysis, prospective studies were identified by searching PubMed and Embase through 22 July 2015, and by reviewing the reference lists of retrieved articles. Study-specific relative risks were combined using a random effects model.

Results: We ascertained 4,311 and 2,730 incident AF cases in men and women, respectively, in the two cohorts. Coffee consumption was not associated with AF incidence in these cohort studies. The lack of association was confirmed in a meta-analysis, including six cohort studies with a total of 10,406 cases of AF diagnosed among 248,910 individuals. The overall relative risk (95 % confidence interval) of AF was 0.96 (0.84 – 1.08) for the highest versus lowest category of coffee consumption, and 0.99 (0.94 – 1.03) per 2 cups/day increment of coffee consumption.

Conclusions: We found no evidence that coffee consumption is associated with increased risk of AF.

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L Wang et al, 2015, Coffee and caffeine consumption and depression: a meta-analysis of observational studies, Australian and New Zealand Journal of Psychiatry, published online ahead of print.

ABSTRACT:

Objective: The results from observation studies on relationship between coffee intakes and risk of depression and relationship between caffeine consumption and depression remains controversial. We conducted a meta-analysis with a dose–response analysis to quantitatively summarize the evidence about the association between coffee and caffeine intakes and risk of depression.

Method: Relevant articles were identified by researching PubMed, Web of Science, China National Knowledge Infrastructure and WANFANG DATA in English or Chinese from 1 January 1980 to 1 May 2015. Case-control, cohort or cross-sectional studies evaluating coffee or caffeine consumption and depression were included. A random-effects model was used to combine study-specific relative risk and 95% confidence interval. Dose–response relationship was assessed by restricted cubic spline functions.

Results: Data were obtained from 11 observation articles; 330,677 participants from seven studies in seven articles were included in the coffee-depression analysis, while 38,223 participants from eight studies in seven articles were involved in the caffeine-depression analysis. Compared with the lowest level consumption, the pooled relative risk (95% confidence interval) for coffee-depression and caffeine-depression was 0.757 [0.624, 0.917] and 0.721 [0.522, 0.997], respectively. For dose–response analysis, evidence of a linear association was found between coffee consumption and depression, and the risk of depression decreased by 8% (relative risk=0.92, 95% confidence interval=[0.87, 0.97], p=0.002) for each cup/day increment in coffee intake; a nonlinear association was found between caffeine consumption and depression, the risk of depression decreased faster and the association became significant when the caffeine consumption was above 68mg/day and below 509mg/day.

Conclusions: Coffee and caffeine consumption were significantly associated with decreased risk of depression.

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J Molnar and J C Somberg, 2015, Evaluation of the effects of different energy drinks and coffee on endothelial function. American Journal of Cardiology, published online ahead of print.

ABSTRACT

Endothelial function plays an important role in circulatory physiology. There has been differing reports on the effect of energy drink on endothelial function. We set out to evaluate the effect of 3 energy drinks and coffee on endothelial function. Endothelial function was evaluated in healthy volunteers using a device that uses digital peripheral arterial tonometry measuring endothelial function as the reactive hyperemia index (RHI). Six volunteers (25 – 7 years) received energy drink in a random order at least 2 days apart. Drinks studied were 250 ml “Red Bull” containing 80 mg caffeine, 57 ml “5-hour Energy” containing 230 mg caffeine, and a can of 355 ml “NOS” energy drink containing 120 mg caffeine. Sixteen volunteers (25 – 5 years) received a cup of 473 ml coffee containing 240 mg caffeine. Studies were performed before drink (baseline) at 1.5 and 4 hours after drink. Two of the energy drinks (Red Bull and 5-hour Energy) significantly improved endothelial function at 4 hours after drink, whereas 1 energy drink (NOS) and coffee did not change endothelial function significantly. RHI increased by 82 – 129% (p [ 0.028) and 63 – 37% (p[0.027) after 5-hour Energy and Red Bull, respectively. The RHI changed after NOS by 2 – 30% (p [ 1.000) and by 7 – 30% (p [ 1.000) after coffee. In conclusion, some energy drinks appear to significantly improve endothelial function. Caffeine does not appear to be the component responsible for these differences.

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L W Chen et al, 2015. Maternal caffeine intake during pregnancy and risk of pregnancy loss: a categorical and dose-response meta-analysis of prospective studies. Public Health Nutrition, published online ahead of print.

ABSTRACT:

OBJECTIVE: To assess the association between maternal caffeine intake and risk of pregnancy loss using a systematic review and meta-analysis.

DESIGN: Categorical and dose-response meta-analysis of prospective studies.

SETTING: Relevant articles were identified by searching MEDLINE and SCOPUS databases through 30 January 2015. Two authors independently extracted information from eligible studies. Random-effects models were used to derive the summary relative risks (RR) and corresponding 95 % CI for specific categories of caffeine consumption and for a continuous association using generalized least-squares trend estimation.

SUBJECTS: A total of 130 456 participants and 3429 cases in fourteen included studies.

RESULTS: Compared with the reference category with no or very low caffeine intake, the RR (95 % CI) of pregnancy loss was 1·02 (0·85, 1·24; I 2=28·3 %) for low intake (50-149 mg/d), 1·16 (0·94, 1·41; I 2=49·6 %) for moderate intake (150-349 mg/d), 1·40 (1·16, 1·68; I 2=18·6 %) for high intake (350-699 mg/d) and 1·72 (1·40, 2·13; I 2=0·0 %) for very high intake (≥700 mg/d). In the dose-response analysis, each 100 mg/d increment in maternal caffeine intake (~1 cup of coffee) was associated with 7 % (95 % CI 3 %, 12 %) higher risk of pregnancy loss. Our results may have been affected by publication bias, but the association remained significant for the subset of larger studies. Furthermore, adjustment for smoking and pregnancy symptoms may have been incomplete, potentially resulting in residual confounding.

CONCLUSIONS: Albeit inconclusive, higher maternal caffeine intake was associated with a higher risk of pregnancy loss and adherence to guidelines to avoid high caffeine intake during pregnancy appears prudent.

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