Vitamins B-12 and C Supplementation Improves Arterial Reactivity and Structure in Passive Smokers: Implication in Prevention of Smoking-Related Atherosclerosis.

BACKGROUND: Atherosclerosis is an important medical problem of modern society. High environmental tobacco smoke in casino is associated with an accelerated atherogenic process. We have previously shown vitamin B12 and C supplementation improves vascular reactivity and may be beneficial in vascular protection. OBJECTIVE: To evaluate the impact of vitamin supplementation on atherosclerosis (brachial artery reactivity FMD and carotid intima-media thickness IMT) in subjects exposed to high environmental tobacco smoke. DESIGN: Double-blind 2x2 factorial design fashion. SETTING: Computer randomization in 4 treatment groups: placebo (n=24), vitamin B12 (n=21), vitamin C (n=23) and vitamin B12+C (n=23) groups. PARTICIPANTS: 91 passive-smoking casino employees (19.2% male, mean age 45.0±8.2 years). INTERVENTION: Subjects were randomized to receive vitamin B12 (500µg daily), vitamin C (200mg daily), vitamin B12+C or image-matched placebo capsules for 1 year. MEASUREMENT: Brachial FMD and carotid IMT (surrogate atherosclerotic markers) were measured by ultrasound at baseline and on completion at 12 months. METHODS: 91 passive smoking casino employees (19.2% male, mean age 45.0±8.2 years) were randomized to receive vitamin B12 (500µg daily), vitamin C (200mg daily), vitamin B12+C or image-matched placebo capsules in double-blind 2 x 2 factorial design fashion for 1 year. Brachial FMD and carotid IMT (surrogate atherosclerotic markers) were measured by ultrasound at baseline and 12 months. RESULTS: Of the 78 (85.7%) passive-smoking employees completed the study, 11.5% had hypertension, 5.1% diabetes mellitus and 15.4% hypercholesterolemia. There were no significant changes in their blood pressures, lipid profiles, glucose and body mass index after supplementation for 1 year, but mild decrease in DBP (p<0.001) and blood creatinine (p<0.01) after combined vitamin B12 and C, and significant increase in blood B12 after vitamin B12 (p<0.01) and vitamin B12+C supplementations (p<0.001). Brachial FMD and cartotid IMT improved after the 3 vitamin supplementations (p<0.001), but not after placebo, being more significant after combined vitamin supplementations (p<0.0001). No adverse effects were reported. CONCLUSION: Vitamin B12 or C supplementation in passive smokers improved vascular reactivity and structures at 1 year, with implication in long term atherosclerosis prevention.

The impact of heavy passive smoking on arterial endothelial function in modernized Chinese.

OBJECTIVES: The study evaluated whether heavy exposure to environmental tobacco smoke (passive smoking) might damage arterial function in modernized Chinese. BACKGROUND: Heavy passive smoking is associated with arterial endothelial dysfunction in Caucasian, but not rural Chinese, subjects. METHODS: We studied 20 young (mean age 36.6 +/- 7.0 years) nonsmoking asymptomatic casino workers (9 men) in Macau who were exposed to environmental tobacco smoke for over 8 h/day for at least two years and 20 normal subjects (control subjects). These two groups were carefully matched for age, gender, body mass index (BMI), blood pressure, vessel diameter, cholesterol and glucose levels. Brachial artery diameter was measured by high-resolution B-mode ultrasound at rest, after flow increase (causing flow-mediated endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator). RESULTS: Flow-mediated dilation (mean +/- SD% of diameter changes) was significantly lower in passive smokers (6.6 +/- 3.4%) compared with the controls (10.6 +/- 2.3%) (p < 0.0001). Nitroglycerin-induced dilation of the two groups were similar. Upon multivariate analysis, passive smoking exposure was the strongest independent predictor (beta = -0.59; p = 0.0001) for impaired flow-mediated endothelium-dependent dilation (model R2 = 0.75, F value = 6.1, p = 0.0001). CONCLUSIONS: In modernized Chinese, as in Caucasians, exposure to heavy environmental tobacco smoke causes arterial endothelial dysfunction, a key early event in atherosclerosis. This may have serious implications for cardiovascular health in China, currently in a process of rapid modernization.

[A survey on prevalence of hypertension in Macao area].

OBJECTIVE: To study the prevalence of hypertension and population blood pressure levels in Macao area. METHODS: According to requirements set in "Manual for National Sampling Survey on Hypertension in 1991", 5,171 permanent residents aged more than 15 years in Macao area were investigated and their blood pressure measured with standardized methods and under strict quality control. RESULTS: The survey showed that crude prevalence rate of hypertension was 29.46 percent in Macao, 20.45 percent after standardization, and it should be categorized into a hypertension prevalent area based on the domestic criteria for hypertension categorization. Systolic and diastolic blood pressure averaged 17.18 kPa (128.82 mmHg) and 10.86 kPa (81.47 mmHg), respectively, for males and 16.32 kPa (122.38 mmHg) and 10.15 kPa (76.15 mmHg), respectively, for females, higher than those in Guangdong Province and Beijing. Prevalence in males was higher than that in females and it increased more quickly in those more than 35 years old, similar to that in the other areas at home. Prevalence in new immigrants was lower than that in the original residents. CONCLUSION: Hypertension was severely prevalent in Macao area and an important issue in public health not to be ignorant. Health education and health promotion should be strengthened to reach the primary and secondary prevention for it.