Estela Kristal-Boneh

Association of Calcitriol and Blood Pressure in Normotensive Men

The purpose of this study was to clarify the possible associations between the serum 1,25-dihydroxyvitamin D (calcitriol) level and blood pressure. Cross-sectional analysis of data was performed. Data collected included levels of serum calcitriol, parathyroid hormone, serum calcium, and blood lead; blood pressure; dietary history; and demographic and anthropometric variables. One hundred normotensive male industrial employees made up the study population. Systolic blood pressure and diastolic blood pressure were main outcome measures. After possible confounders were controlled for, multivariate analyses yielded an inverse, independent, and statistically significant association between calcitriol level and systolic blood pressure (standardized beta= -0.2704, P=.0051). A similar trend of borderline significance was found for the association between calcitriol and diastolic blood pressure (standardized beta= -0.1814, P=.0611). Parathyroid hormone, serum calcium, and blood lead levels were not associated with blood pressure. When subjects were divided into four groups by calcitriol level, those in the lowest quartile showed significantly higher systolic and diastolic blood pressures than those in the upper quartile (difference=11 mmHg, P=.007, and difference=4 mmHg, P=.071, respectively). There is an inverse association between serum calcitriol level and blood pressure. This suggests that in addition to its role in calcium homeostasis, the active metabolite of vitamin D may play a role in determining blood pressure. The differences in both systolic and diastolic blood pressures between the upper and lower quartiles of serum calcitriol were substantial and may be of clinical significance.

Changes in dietary intake account for seasonal changes in cardiovascular disease risk factors.

Objectives: (1) to compare dietary intake in summer and winter time; (2) to measure the change in body mass index (BMI), blood pressure and serum cholesterol between winter and summer; and (3) to determine the relationships between seasonal differences in dietary intake and BMI, blood pressure and serum cholesterol measurements.Subjects and methods: Ninety-four male industrial employees were screened twice in one year, in their work place, at winter and summer time. Workers were recruited from two factories and response rate was 95%. Health-related variables, including dietary intake, blood pressure and serum cholesterol were evaluated at each season and were compared. Correlation coefficients between seasonal differences in dietary intake and in BMI, blood pressure and serum cholesterol were calculated.Results: From summer to winter the mean values of BMI increase from 26.1 kg/cm2 to 26.6 (P=0.038), systolic blood pressure from 119.6 to 121.6 (P=0.025), diastolic blood pressure from 75.2 to 77.2 mmHg (P=0.001), total cholesterol from 200.8 to 208.6 mg/dL (P=0.001), LDL cholesterol from 125.2 to 134.9 (P=0.001) and HDL cholesterol from 42.7 to 44.3 (P=0.0084). Triglycerides levels decrease from 174 to 145 in the winter (P=0.03). Mean dietary intake of fat increases from 99.1 to 106.0 (P=0.0016), saturated fat from 43.6 to 46.3 (P=0.0137), polyunsaturated fat from 25.1 to 28.3 (P=0.0002), cholesterol from 462.0 to 497.9 (P=0.0313), sodium from 5778.5 to 8208.2 (P=0.0035), zinc from 11.6 to 12.3 (P=0.0001), vitamin B1 from 1.4 to 1.5 (P=0.002), vitamin D from 4.3 to 4.9 (P=0.0323) and vitamin E from 11.2 to 12.7 (P=0.0073). Significant correlation was shown between the seasonal increase in saturated fat and the increase in BMI (r=0.37), total cholesterol (r=0.21) and LDL cholesterol (r=0.29). Seasonal change in dietary cholesterol intake was significantly and positively correlated with serum total cholesterol (r=0.24) and LDL cholesterol (r=0.24). Blood pressure was not associated with nutritional intake variables.Conclusions: Dietary intake in summer and winter is different as well as blood pressure, BMI and serum cholesterol. The seasonal increase in fat and cholesterol intake at winter time is associated with changes in BMI and serum cholesterol.Sponsorship: The study was supported by the committee for preventive Action and Research in Occupational Health, the Ministry of Labor and Social Affairs, Jerusalem, Israel.Guarantor: Dr Estela Kristal-Boneh.

Association of physical activity at work with mortality in Israeli industrial employees: the CORDIS study.

The objective of this study was to evaluate the association of physical activity at work with the risk of all-cause cardiovascular disease and cancer mortality. The cohort consisted of 3488 male, Israeli, industrial employees who participated in an 8-year follow-up study. During this period 129 deaths were recorded: 54 from cardiovascular disease, 47 from cancer, and 28 from other causes. Physical activity at work was assessed at entry on a 4-point scale (none, light, medium, and high). Potential confounding demographic, anthropometric, and socioeconomic variables, and health habits including leisure time physical activity were accounted for. We found that the hazard ratio of all-cause mortality in workers with a high physical workload was 1.82 (95% confidence interval, 1.18 to 2.81) compared with workers having a low workload. A similar trend was noted for cardiovascular disease and cancer mortality. We concluded that a high physical workload is associated with increased mortality rates. Future studies should differentiate between leisure time and work time physical activity.

Seasonal variations in dietary intake affect the consistency of dietary assessment

Background: Nutritional epidemiology studies are usually based on one dietary assessment without taking into account the season in which the interview is taken or adjusting for the difference in reporting dietary intake in different seasons. The semiquantitative food frequency questionnaire has become the primary questionnaire method for measuring dietary intake in epidemiological studies. The aims of this report were (a) to evaluate the effect of season on dietary intake as measured by a semiquantitative food frequency questionnaire (FFQ) conducted twice: once in summer and a second time in winter; and (b) to assess the effect of the differences in dietary intake on biochemical and anthropometric seasonal related changes, such as serum cholesterol and body mass index (BMI). Population and methods: The study population consisted of 94 male industrial employees who participated in clinical biochemical and physical examinations as well as evaluation of their dietary intake twice a year. Dietary intake was assessed using the semiquantitative FFQ that included 96 items and was conducted by a personal interview. Results: We found a significant increase in the intake of selected nutrients in winter as compared to summer as well as an increased intake of animal fat-containing foods such as meat and dairy products. Significant correlation coefficients were shown between the increase in dietary intake of saturated fat and the increase in BMI, serum total and LDL cholesterol. The increase in dietary cholesterol was significantly and positively correlated with the increase in serum total and LDL cholesterol. Conclusion: Although FFQ are designed to assess average yearly food intake, we identified significant seasonal changes in dietary intake as measured by FFQ. These changes have a health impact on our population.

Seasonal change in 24-hour blood pressure and heart rate is greater among smokers than nonsmokers

In general, blood pressure is higher in winter than in summer, and this factor may be partly responsible for the higher mortality from cardiovascular disease in winter. Cigarette smoking causes an acute pressor response that may interact with this cardiovascular response to cold exposure. We sought to determine whether the seasonal variation in blood pressure and heart rate differs between cigarette smokers and nonsmokers. We evaluated 24-hour ambulatory systolic blood pressure (SBP), ambulatory diastolic blood pressure (DBP), and ambulatory heart rate of 97 healthy men (73 nonsmokers and 24 smokers), 28 to 63 years of age, during the summer and winter, taking indoor temperatures into consideration. Smokers and nonsmokers both had higher daytime ambulatory SBPs and DBPs in winter than in summer (after adjustment for potential confounders). However, the winter increase seen in the smokers was significantly higher for mean daytime SBP (7.3 versus 2.7 mm Hg, P<.01), for mean daytime DBP (4.4 versus 3.1 mm Hg, P=.051), and for ambulatory heart rate (3.9 versus -1.7 beats/min, P<.001). The double product increased from summer to winter (daytime) by 10.53 for smokers and by only 0.11 for nonsmokers (P<.01). There was an independent interaction between season and smoking status that affected SBP (standardized beta=0.66, P<.0001) and DBP (standardized beta=0.32, P<.0001). Smokers have a greater seasonal variation in blood pressure and heart rate than nonsmokers and show a larger increase in the cardiovascular load in winter. Smoking apparently potentiates the cardiovascular response to various climatic conditions. Season should be taken into account in studies of blood pressure and in the diagnosis and treatment of hypertension, particularly among cigarette smokers.

Industrial accidents are related to relative body weight : the Israeli CORDIS study

OBJECTIVES: The accident rate might be influenced by intrinsic characteristics of the workers, by risks inherent in the work environment, or a combination of these factors. As increased weight may be associated with sleep disturbances and fatigue, a high body mass index (BMI) might be an independent risk factor for accidents in industrial workers. METHODS: 3801 men were examined and followed up for two years for the occurrence of accidents. The objective environmental conditions were recorded and translated into a single score of ergonomic stress levels. Height and weight were recorded, as were possible confounding factors including measures of fatigue, type A personality, total night time sleep, job satisfaction, somatic complaints, smoking, and education levels. RESULTS: Both BMI and ergonomic stress levels independently predicted involvement in accidents (two or more) with those in the highest BMI quartile who worked in an environment with high ergonomic stress levels having a 4-6 times increased risk of accidents compared with those in the lowest BMI quartile who worked in an environment with low ergonomic stress levels (95% confidence interval (95% CI) 2.4-9.0, P < 0.001). Although increasing somatic complaints and a low educational level also were predictors of accidents, they did not mediate the effect of the BMI on the accident rate. Increasing age, less smoking, and decreased sleep hours were significantly associated with an increased BMI, but the association of BMI and involvement in accidents also could not be explained by those factors or the other confounders. CONCLUSIONS: BMI independently influences the accident rate. Further studies warranted to confirm these findings and to explore mechanisms supporting biological plausibility.

Summer-Winter Differences in 24 h Variability of Heart Rate:

Objective To examine possible seasonal changes in heart rate variability (HRV). Background Greater than normal mortality from cardiovascular disease (CVD) in the winter has been reported for many countries and might be partly explained by considering seasonal changes in CVD risk factors. Depression of HRV is an independent predictor of arrhythmic complications and of cardiac death, and it is also among the variables that may be affected by the season of the year. Methods We compared pairs of 24 h HRV data of 120 healthy men who were examined once in the summer and once in the winter. Multivariate analyses were performed for each dependent variable (HRV indexes) in separate statistical models with age, resting heart rate, serum level of cholesterol, cigarette smoking, body mass index, sports habits, alcohol consumption, systolic blood pressure, physical activity at work, years of education, consumption of energy, and season as the independent variables. Results Although there were no seasonal differences in mean R–R interval, all indexes of HRV were found to be lower in the summer than they were during winter. Differences and 95% confidence intervals were standard deviation (SD) of coupling intervals between normal beats 12 ms, 6–17 ms; SD of 5 min mean R–R intervals 14 ms, 8–20 ms; mean of all 5 min SD of R-R intervals 2.0 ms, 0.6–2.5 ms; proportion of adjacent R-R intervals differing by > 50 ms 1.5%, 0.6–2.5% and root mean square of the difference between successive normal intervals 3.1 ms, 1.5–4 ms. Multivariate analyses showed that HRV in the winter was less than that in the summer even after adjustment for age, serum level of cholesterol, systolic blood pressure, and body mass index. Conclusions HRV indexes of healthy men vary physiologically by season, with lowest values obtained in the winter. Since low HRV is linked to pathologic conditions, the significance of seasonal changes for those suffering from CVD and their possible contribution to the greater mortality rates in winter have to be considered.

Acute and Chronic Effects of Noise Exposure on Blood Pressure and Heart Rate among Industrial Employees: The Cordis Study

The effects of industrial noise on resting heart rate and blood pressure were studied in 3,105 blue-collar workers. Heart rate and blood pressure were measured in different workers at various times during the workday. After controlling for several possible confounders, we found that resting heart rate in females was associated positively with noise intensity (p = .036) and with time of day (p = .054). In males, resting heart rate was associated with noise intensity; however, such association was related to time of day (p = .046). No such associations were found for blood pressure in either sex. We plotted the mean resting heart rate by time of day for workers exposed to high [ > or = 80 db(A)] and low noise, and no difference was evident with respect to morning heart rate in either sex. After 4 h of noise exposure for males (and less time for females), individuals who were exposed to high noise had higher heart rates; however, in females this was not observed at the end of the workday. Thus, recurrent daily exposure to high noise at work has an acute, though not residual, effect on resting heart rate.

Body Mass Index is Associated with Differential Seasonal Change in Ambulatory Blood Pressure Levels

Seasonal changes in blood pressure may be partially explained in thermoregulatory terms. We hypothesized that the seasonal variation in blood pressure is related to body mass index, due to the increased thermoregulatory requirements of leaner individuals. Ambulatory systolic and diastolic blood pressure were monitored once each in summer and winter in 101 healthy normotensive men aged 28 to 63 years. Environmental conditions and body mass index were measured. The population was divided according to quartiles of body mass index. The percentage of subjects with systolic blood pressure increases of more than 10 mm Hg from summer to winter was highest among subjects in the lowest body mass index category, and lowest among those in the highest body mass index category (35% and 8%, respectively, P < .0001). After adjusting for possible confounders, the change in mean systolic blood pressure from summer to winter was inversely associated with body mass index (beta = -0.26, P = .0149). There was no association between diastolic blood pressure change and body mass index. The increase in systolic blood pressure from summer to winter is inversely and independently associated with body mass index. Hypertension research and epidemiological blood pressure studies should take into account the interaction between season, body mass index, and blood pressure. It may also be important to assess hypertension and response to antihypertensive treatment in relation to season, particularly in lean hypertensives.

Industrial Noise Exposure, Noise Annoyance, and Serum Lipid Levels in Blue-Collar Workers–The CORDIS Study

Chronic noise exposure may constitute a risk factor for cardiovascular disease, but the exact mechanism is unclear. The authors studied the association between industrial noise exposure, noise annoyance, and serum lipid/lipoprotein levels in male (n = 1,455) and female (n = 624) blue-collar workers. The authors found that young men (i.e., < or = 44 y of age) exposed to high noise levels (> or = 80 dB[A]) had higher total levels of cholesterol (p = .023) and triglycerides (p = .001), as well as a higher cholesterol ratio (p = .038), than men exposed to low noise levels, even after controlling for confounding variables. In women or in older (> 45 y) men, noise did not affect serum lipid/lipoprotein levels. The authors found no interaction between noise exposure level and noise annoyance (except for high-density lipoprotein in women). However, noise annoyance covaried independently with total cholesterol (p = .022) and high-density lipoprotein (p = .0039) levels in young men and with total cholesterol (p = .035), triglyceride (p = .035), and high-density lipoprotein levels in women (under high noise exposure conditions)(p = .048) levels in women. Noise annoyance and noise exposure levels had an additive effect on cholesterol levels. Young men who scored high on both variables had a 15-mg/dl higher mean cholesterol level (95 % confidence interval [CI] = 7.2, 22.8; p = .0003) than those who scored low on both variables; in women, the corresponding difference was 23 mg/dl (95% CI = 1.5, 42.9; p = .019). The authors concluded that the examination of serum lipid/lipoprotein levels may be useful in studies of the health effects of noise, and particular attention should be paid to noise-annoyed individuals.