Habitual coffee intake reduces all-cause mortality by decreasing heart rate

Development of algorithm for work intensity evaluation using excess overwork index of construction workers with real-time heart rate measurement device

Background

The construction workers are vulnerable to fatigue due to high physical workload. This study aimed to investigate the relationship between overwork and heart rate in construction workers and propose a scheme to prevent overwork in advance.

Methods

We measured the heart rates of construction workers at a construction site of a residential and commercial complex in Seoul from August to October 2021 and develop an index that monitors overwork in real-time. A total of 66 Korean workers participated in the study, wearing real-time heart rate monitoring equipment. The relative heart rate (RHR) was calculated using the minimum and maximum heart rates, and the maximum acceptable working time (MAWT) was estimated using RHR to calculate the workload. The overwork index (OI) was defined as the cumulative workload evaluated with the MAWT. An appropriate scenario line (PSL) was set as an index that can be compared to the OI to evaluate the degree of overwork in real-time. The excess overwork index (EOI) was evaluated in real-time during work performance using the difference between the OI and the PSL. The EOI value was used to perform receiver operating characteristic (ROC) curve analysis to find the optimal cut-off value for classification of overwork state.

Results

Of the 60 participants analyzed, 28 (46.7%) were classified as the overwork group based on their RHR. ROC curve analysis showed that the EOI was a good predictor of overwork, with an area under the curve of 0.824. The optimal cut-off values ranged from 21.8% to 24.0% depending on the method used to determine the cut-off point.

Conclusion

The EOI showed promising results as a predictive tool to assess overwork in real-time using heart rate monitoring and calculation through MAWT. Further research is needed to assess physical workload accurately and determine cut-off values across industries.

Association of heart rate and diabetes among 0.5 million adults in the China Kadoorie biobank: Results from observational and Mendelian randomization analyses

BACKGROUND AND AIMS

Observational studies have associated resting heart rate with incident diabetes. Whether the associations are causal remains unclear. We aimed to examine the shape and strength of the associations and assessed the causal relevance of such associations in Chinese adults.

METHODS AND RESULTS

The China Kadoorie Biobank enrolled 512,891 adults in China. Cox proportional hazard regression models was conducted to estimate hazard ratios (HRs) for the associations of resting heart rate with type 2 diabetes and total diabetes. Among 92,724 participants, 36 single-nucleotide polymorphisms (SNPs) related to resting heart rate were used to construct genetic risk score. We used Mendelian randomization analyses to make the causal inferences. During a median follow-up of 9 years, 7872 incident type 2 diabetes and 13,349 incident total diabetes were documented. After regression dilution bias adjustment, each 10 bpm higher heart rate was associated with about a 26% higher risk of type 2 diabetes (HR, 1.26 [95% CI, 1.23, 1.29]) and 23% higher risk of total diabetes (HR, 1.23 [95% CI, 1.20, 1.26]). Instrumental variable analyses showed participants at top quintile compared with those at bottom quintile had 30% higher risk for type 2 diabetes (HR, 1.30 [95% CI, 1.17, 1.43]), and 10% higher risk for total diabetes (HR, 1.10 [95% CI, 1.02, 1.20]).

CONCLUSIONS

This study provides evidence that resting heart rate is an important risk factor for diabetes risk. The results suggest that novel treatment approaches targeting reduction of high heart rate for incidence of diabetes may be worth further investigation.

Differential impacts of 24 hour urinary sodium excretion on cardiovascular diseases or cancer mortality in a general population

BACKGROUND

Elevated blood pressure is a major risk factor for cardiovascular (CV) disease. But the effects of sodium intake or excretion on CV mortality are uncertain. The present study aimed to investigate the association between 24 h urinary sodium excretion, as a marker of dietary salt intake, and CV or cancer mortality in a healthy Japanese population using 24 hurine collection.

METHODS

The baseline study was conducted in 1980. A total of 1291 participants aged 21 to 85 years, underwent health check-ups, which included blood chemistry measurements and the collection of 24 h urine samples. Enrolled 1291 participants were followed up for 27.5 years, in whom the final follow-up rate was 95.8%. Cox proportional hazards regression models were used to assess the association between 24 h urinary sodium excretion and CV or cancer mortality.

RESULTS

The mean 24 h urinary sodium excretion was 5.80 ± 2.28 g/day. There were 631 deaths: 153 (27%) from cancer, 142 (26%) from CV disease. In the Cox proportional hazard regression model after adjustment for confounding factors, systolic and diastolic blood pressures, and uric acid were positively associated with CV mortality, and the 24 h urinary sodium and potassium excretions were inversely associated with CV mortality (p < 0.05). On the other hand, there were no association between 24 h urinary sodium excretions and cancer mortality. We divided the urinary sodium excretions levels into quartiles. After adjustment for confounding factors, the hazard ratio of CV mortality in the highest quartile of 24 h urinary sodium excretion versus the lowest was 0.46 (p < 0.05). The cumulative survival rate for CV death was significantly decreased in the lowest quartile compared with the other higher groups.

CONCLUSIONS

We found that impacts of 24 h sodium excretion on CV and cancer mortalities were much different in the general population.

Dietary Research on Coffee: Improving Adjustment for Confounding

Meta-analyses have reported higher levels of coffee consumption to be associated with lower mortality. In contrast, some systematic reviews have linked coffee consumption to increased risks for lung cancer and hypertension. Given these inconsistencies, this narrative review critically evaluated the methods and analyses of cohort studies investigating coffee and mortality. A specific focus was adjustment for confounding related to smoking, healthy and unhealthy foods, and alcohol. Assessment of 36 cohort samples showed that many did not adequately adjust for smoking. Consuming 1-5 cups of coffee per day was related to lower mortality among never smokers, in studies that adjusted for pack-years of smoking, and in studies adjusting for healthy and unhealthy foods. Possible reduced health benefits for coffee with added sugar have not been adequately investigated. Research on coffee and health should report separate analyses for never smokers, adjust for consumption of healthy and unhealthy foods, and for sugar added to coffee.