Cardiovascular disease
Summary
The relationship between the use of Swedish snus and cardiovascular disease has been examined in several studies. Due to the presence of nicotine, which is known to cause acute increase in heart rate and blood pressure, some scientists have assumed that the use of snus can affect the cardiovascular system.
The body of published literature examining the relationship between the use of Swedish snus and various measures of cardiovascular disease includes several descriptive studies, two case-control studies, a prospective cohort study and an experimental study. The outcomes studied include general health status, clinical risk factors for cardiovascular disease, development of atherosclerosis, hypertension, the risk of myocardial infarction and mortality from cardiovascular disease.
Important research results on Swedish snus:
- There exists a relationship between the use of snus and the acute effects on the cardiovascular system such as acute increase in blood pressure and heart rate.
- There exists a relationship between the use of snus and impaired flow-mediated dilation of the brachial artery.
- It remains unclear whether the use of snus is a risk factor for hypertension.
- There is no association between the use of snus and atherosclerosis or risk factors for atherosclerosis.
- There is no evidence of an increased risk of myocardial infarction in snus users.
- There are conflicting results whether the use of snus causes an increased mortality from cardiovascular disease.
- Smokeless tobacco (mainly snus) is associated with significantly lower risk of cardiovascular outcomes than smoking, illustrated in the figure below (Asplund, 2003).
Advanced
Acute cardiovascular effects
Bolinder and de Faire (1998) studied acute effects of tobacco use on the cardiovascular system in a group of middle aged firefighters. They found that during daytime both snus users and smokers, who were 45 years of age or older, had increased heart rate and increased diastolic blood pressure. During night, when tobacco was not used, heart rate and blood pressure was not elevated.
In another study also comprising the same group of firefighters, Bolinder et al. (1997a) found that the heart rate tended to be 6 beats per minute faster, the systolic blood pressure 10-15 mmHg higher and the diastolic blood pressure 6 mmHg higher in snus users who had recently (<2 hours previously) used snus than in those who had refrained from snus for more than 2 hours before measurement. These temporal relationships between use of snus and effects on blood pressure and heart rate support the view that snus use causes acute cardiovascular effects. Rohani et al. (2004) found an acute impaired ability of the vascular system to dilate in response to increased blood flow in a group of middle-aged snus users.
Hypertension
Although snus use can be linked to acute changes in blood pressure, considerable uncertainty exists as to whether snus use can cause hypertension. In a cross sectional study of a large population of Swedish construction workers, Bolinder et al. (1992) showed that middle aged snus users had a significantly higher risk of mild hypertension (diastolic blood pressure >90 mmHg or systolic blood pressure >160 mmHg) than middle aged non-tobacco users.
Two other studies by Eliasson et al. (1991) and Bolinder et al. (1997a) comprising a group of young men and a group of middle aged firefighters, respectively, failed to note differences between snus users and non-tobacco users with respect to blood pressure.
Atherosclerosis and risk factors for atherosclerosis
The available studies of Swedish snus do not indicate an association between snus use and either atherosclerosis or risk factors for this disease. Bolinder et al. (1997b) estimated the degree of atherosclerosis in a group of firefighters by measurement of the carotid artery wall thickness. They found no significant difference between snus users and non-tobacco users in this respect. In other studies of Bolinder et al. (1997b,c) and Eliasson et al. (1991, 1995) no association was found between snus use and risk factors for atherosclerosis (blood lipid levels, fibrinogen levels, fibrinolytic activity, insulin resistance).
Myocardial infarction
The influence of snus use on the incidence of myocardial infarction was examined in three population based case control studies. Two of these comprised middle aged men in two Northern counties of Sweden (Huhtasaari et al. 1992, 1999). Neither of these two studies found an increased risk of myocardial infarction associated with snus use. The results did not, however, exclude a small or modest detrimental effect of snus use on the risk for sudden death.
In a recently published case-control study conducted in two Swedish counties comprising 1760 men, age 45-70 years, the relationship between the long–term use of Swedish snus and the increased risk of acute myocardial infarction was assessed. The relative risk of a first acute myocardial infarction was 1.1 for former snus users and 1.0 for current snus users. Accordingly, this study showed that snus use is not associated with an increased risk for myocardial infarction (Hergens et al., 2005).
Mortality from cardiovascular disease
In a prospective cohort study comprising a large number of construction workers Bolinder et al. (1994) found an association between snus use and increased risk of death from all cardiovascular diseases for the age group 35-45 years but not for the age group 55-65 years.
REFERENCES
Asplund, K. 2003. Smokeless tobacco and cardiovascular disease. Progress in Cardiovascular Disease 45: 383-394. Bolinder, G.M., Ahlborg, B.O., and Lindell, J.H. 1992. Use of smokeless tobacco: Blood pressure elevation and other health hazards found in a large-scale population survey. J. Int. Med. 232:327-334. Bolinder, G., Alfredsson, L., Englund, A., and de Faire, U. 1994. Smokeless tobacco use and increased cardiovascular mortality among Swedish construction workers. Am. J. Public Health 84:399-404. Bolinder, G., Norén, A., Wahren, J., and de Faire, U. 1997a. Long-term use of smokeless tobacco and physical performance in middle-aged men. Eur. J. Clin. Invest. 27:427-433. Bolinder, G., Norén, A., de Faire, U., and Wahren, J. 1997b. Smokeless tobacco use and atherosclerosis: An ultrasonic investigation of carotid intima media thickness in healthy middle-aged men. Atherosclerosis 132:95-103. Bolinder, G., Norén, A., Wahren, J. and de Faire, U. 1997c. Long-term use of smokeless tobacco: Cardiovascular mortality and risk factors. PhD thesis, University of Stockholm, Stockholm. Bolinder, G. and de Faire, U. 1998. Ambulatory 24-h blood pressure monitoring in healthy, middle-aged smokeless tobacco users, smokers, and nontobacco users. Am. J. Hypertens. 11:1153-1163. Eliasson, M., Lundblad, D., and Hägg, E. 1991. Cardiovascular risk factors in young snuff-users and cigarette smokers. J. Int. Med. 230:17-22. Eliasson, M., Asplund, K., Evrin, P.E., and Lundblad, D. 1995. Relationship of cigarette smoking and snuff dipping to plasma fibrinogen, fibrinolytic variables and serum-insulin: The northern Sweden MONICA study. Atherosclerosis 113:41-53. Hergens, M.-P., Ahlbom, A., Andersson, T., and Pershagen, G. 2005. Swedish moist snuff and myocardial infarction among men. Epidemiology 16: 12-16. Huhtasaari, F., Asplund, K., Lundberg, V., Stegmayr, B., and Wester, P.O. 1992. Tobacco and myocardial-infarction: Is snuff less dangerous than cigarettes?. Br. Med. J. 305:1252-1256. Huhtasaari, F., Lundberg, V., Eliasson, M., Janlert, U., and Asplund, K. 1999. Smokeless tobacco as a possible risk factor for myocardial infarction: A population-based study in middle-aged men. J. Am. Coll. Cardiol. 34:1784-1790. Rohani, M., Agewall, S. 2004. Oral snuff impairs endothelial function in healthy snuff users. J. Int. Med. 255: 379-383.
