Original ResearchEffects of smoking and alcohol consumption on lipid profile in male adults in northwest rural China
Introduction
Dyslipidaemia is defined as an abnormal level of lipid in the blood and is characterised by increased levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) and a decreased level of high-density lipoprotein cholesterol (HDL-C). Dyslipidaemia is prevalent among adults worldwide; for example, 53% (105.3 million) of adults in the United States have lipid abnormalities.1 In China, it has been reported that the prevalence of dyslipidaemia is 34.0% in the total population and 26.3% in rural areas.2 In addition, in China, the prevalence of dyslipidaemia is significantly higher in males (41.9%) than females (32.5%).2 Dyslipidaemia is an important risk factor for cardiovascular disease.3, 4 A study reported that the hazard ratio for coronary heart disease was 2.52 (95% confidence interval [CI]: 1.15–5.07) in males with high TC compared with males with low TC.5 A cohort study comprised of 15,335 patients showed that high TG is independently associated with increased all-cause mortality in patients with coronary heart disease.6 LDL-C is a strong independent predictor of coronary heart disease in individuals with diabetes.7 An inverse relationship has been reported between HDL-C and coronary heart disease, and an isolated low HDL-C was more prevalent among Asian populations.8 The body of research suggesting that the TG/HDL-C ratio is a powerful independent predictor of all-cause mortality and cardiovascular events is growing.9 In addition to a malfunction of lipid metabolism, many epidemiological studies have found that a small number of modifiable behavioural risk factors (e.g. smoking and alcohol consumption) are major contributors to the development of cardiovascular disease.
Research has shown that smoking and alcohol consumption are strong risk factors for dyslipidaemia. Smoking decreases HDL-C and increases TG, whereas alcohol consumption increases both HDL-C and TG.10 Smoking cessation improves lipid metabolism.11 A study among Chinese nonagenarians/centenarians found that smoking habits were not associated with increased risk of dyslipidaemia, which differed from the results found in the general population.12 It has been reported that alcohol consumption increases TC and HDL-C but has no significant effect on TG, except at high levels of consumption.13 Some animal experiments and epidemiological studies found that chronic alcohol intake increased serum HDL-C significantly.14
Smoking and drinking behaviours often coincide, which has a reciprocal influence on potentiating tendency.15 Most previous studies have focused on evaluating the influences of smoking and alcohol consumption on dyslipidaemia. However, their combined influence remains unclear. Therefore, the present study was undertaken to explore the influences of smoking and alcohol consumption, individually and in combination, on lipid profile and dyslipidaemia among the rural Chinese population, among whom the prevalence rates of overweight and obesity are substantially lower than in Western populations, largely due to differences in dietary and lifestyle factors.
Section snippets
Study design and participants
A cross-sectional survey was carried out from 2008 to 2012 in Yuanzhou District, Qingtongxia City and Pingluo County in Ningxia Hui Autonomous Region, China. This cross-sectional survey has been described previously.16 In brief, the survey enrolled 4614 subjects who were rural residents in northwest China, aged 18–75 years. During the study period, 4614 subjects (3591 females and 1023 males) provided general demographic and lifestyle data via interview and underwent a physical examination.
Results
Of the 707 subjects, 330 were classified as smokers and 377 were classified as non-smokers; mean ages were 46.2 (SD: 11.6) years and 49.0 (SD: 12.6) years, respectively. As shown in Table 1, HDL-C was significantly lower in smokers than in non-smokers. Also, smokers had significantly higher TC/HDL-C, TG/HDL-C and LDL-C/HDL-C ratios and VAI than non-smokers (all P < 0.05).
Table 2 shows that the TG/HDL-C and LDL-C/HDL-C ratios and TG, LAP and VAI were significantly higher in drinkers than in
Discussion
This study explored the individual and combined effects of smoking and alcohol consumption on lipid profile. TC/HDL-C, TG/HDL-C and LDL-C/HDL-C ratios and VAI were higher in smokers compared with non-smokers, whereas HDL-C was lower in smokers. TG/HDL-C and LDL-C/HDL-C ratios, TG, LAP and VAI were higher in drinkers than in non-drinkers. The OR for any dyslipidaemia was 1.94 (95% CI: 1.09–3.48) for comparing the co-smoking and drinking subjects with subjects who did not smoke or drink alcohol.
Acknowledgements
The authors would like to thank the village doctors of all participating villages for their support with subject recruitment, and the study participants for their willingness to be interviewed and donate blood samples. Finally, the authors wish to thank all investigators for their contributions to the research.
Ethical approval
This study was approved by the Medical Ethics Review Committee of Ningxia Medical University.
Funding
This work was supported by Natural Science Foundation of China (No. 81160358).
Competing interests
None declared.
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