3.28 Health 'benefits' of smoking?

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3.0 Background

3.1 Tobacco—a leading preventable cause of death and disease

3.2 Cardiovascular diseases

3.3 Lung cancer

3.4 Respiratory diseases

3.5 Other cancers caused by or associated with smoking

3.6 Reproductive health and smoking

3.7 Pregnancy and smoking

3.8 Infant health and smoking

3.9 Increased susceptibility to infection in smokers

3.10 Eye diseases

3.11 Dental diseases

3.12 Gastrointestinal diseases

3.13 Bone density and risk of fractures

3.14 Effects of smoking on the skin

3.15 Smoking and complications in medical treatment

3.16 Smoking and diabetes

3.17 Poorer levels of general health

3.18 Smoking, motor vehicle crashes and other injuries

3.19 Burns and fires caused by tobacco use

3.20 Tobacco poisoning

3.21 Health effects for younger smokers

3.22 Genetic influences on tobacco-caused disease

3.23 Smoking, dementia and cognitive decline

3.24 Lung disease, smoking and occupational exposures

3.25 Air pollution, cigarette smoking and ill health

3.26 Health effects of smoking brands that claim to deliver lower levels of tar, nicotine and carbon monoxide

3.27 Health effects of smoking tobacco in other forms

3.28 Health 'benefits' of smoking?

3.29 Morbidity (ill health) attributable to tobacco-caused disease

3.30 Deaths attributable to tobacco by disease category

3.31 Morbidity and mortality due to tobacco-caused disease and socioeconomic disadvantage

3.32 Health effects of smoking other substances

3.33 Health effects of chewing tobacco, and of other smokeless tobacco products

3.34 Public perceptions of tobacco as a drug, and knowledge and beliefs about the health consequences of smoking

3.35 Health benefits of cessation

3.36 The global tobacco pandemic

Acknowledgments

References

Important note: smoking may offer a limited degree of protection in some individuals against the development of a small number of diseases, outlined below. However, this information is of no relevance to public health, given that the amount of disease that tobacco may be said to prevent is insignificant in comparison to the far greater incidence of disease caused by smoking. Smoking kills one in two of its users.2

Tobacco use confers a small degree of protection against several diseases and conditions, described in the sections below. It is estimated that in 2004–05, tobacco use prevented about 148 deaths, a very low number compared to the 15,050 deaths, in Australia caused by smoking.[7]7 On the basis of these figures, tobacco can be said to save about one life for every 100 deaths it causes. Moreover, there is nothing to suggest that possible protection conferred against one disease will stop a given smoker from developing another tobacco-caused disease. So, for example, an individual who may have avoided Parkinson's disease due to his or her smoking still runs a significant risk of dying from heart disease, lung cancer, or any of the multiplicity of other tobacco-caused diseases. Equally, smoking does not prevent Parkinson's disease in all smokers.

While tobacco use cannot in any way be recommended as a prophylactic for these diseases and conditions, research on the mechanisms by which smoking appears to confer a protective effect against development of certain disease processes may lead to therapeutic benefits.166

3.28.1 Ulcerative colitis

Ulcerative colitis is a serious bowel disease in which the inner lining of the colon and rectum becomes inflamed and permanently damaged.

Current smokers have a lower risk of developing ulcerative colitis, compared to non-smokers and ex-smokers. Nicotine in tobacco smoke is thought to be the component that is most likely to affect the course of the disease.66

However, smokers have a greater risk of developing Crohn's Disease, another inflammatory disease of the bowel (see Section 3.12.2 above). Due to the devastating effects of tobacco use, smoking is not recommended as treatment for ulcerative colitis. Various forms of nicotine therapy are undergoing research to evaluate any possible benefits for individuals with this bowel disease.66

3.28.2 Parkinson's disease

An association between smoking and a lower incidence of Parkinson's disease has been observed in a number of studies.167 Nicotine is thought to be the chemical in tobacco smoke mostly likely to be implicated in this finding, but there may be other chemicals or compounds involved.168 Based on data from 2004–05 it is estimated that about 97 deaths from Parkinson's disease are prevented by smoking in Australia annually.20

3.28.3 Endometrial cancer and uterine fibroids

Smoking offers a protective effect against developing cancer of the endometrium (the membrane lining of the uterus) in women who have reached menopause.15 Women who smoke may also have a decreased risk for uterine fibroids, and for endometriosis, but the evidence for this is not conclusive.15 Development of endometrial cancer is predominantly influenced by exposure to the hormone oestrogen, and the protection conferred by smoking is likely to be due to the 'anti-oestrogenic' effect of chemicals in tobacco smoke. This same interaction works to increase the risk among smokers of reaching menopause earlier than non-smokers and of developing osteoporosis (see Sections 3.6.1.3 and 3.13).15

It has been estimated that smoking prevented the loss of some 52 lives from endometrial cancer in Australia in 2004–05.20 However, the numbers of lives saved which can be statistically attributed to the prevention of endometrial cancer among smokers pales into insignificance compared with the numbers of deaths due to other diseases caused by tobacco use, particularly in the light of the recent confirmation that smoking causes cancer of the uterine cervix.5

3.28.4 Pre-eclampsia (hypertension in pregnancy)

Pre-eclampsia is a potentially serious condition in pregnancy in which the mother develops high blood pressure, fluid retention and abnormal kidney function. Smokers are less likely to develop pre-eclampsia than non-smokers, although the mechanism by which this occurs is not yet understood.5 The US Surgeon General has concluded that 'the decreased risk of pre-eclampsia among smokers compared with non-smokers does not outweigh the adverse outcomes that can result from prenatal smoking.'5 p 576

3.28.5 Reduced body weight

The relationship between smoking and reduced body weight is widely recognised by smokers, and generally overestimated. While it is true that smokers weigh, on average, less than people who have quit smoking and those who have never smoked, the effect is modest and accrues over decades of smoking. Starting smoking does not appear to be associated with weight loss.15

There is no doubt that a proportion of smokers perceive the possibility of reduced bodyweight as a benefit, and since being overweight is strongly associated with many disease entities, it has also given rise to the question of whether it is better to be a leaner smoker or a heavier non-smoker. A large international study has investigated the connection between smoking, body weight and mortality from CHD.169 The study concludes that although smokers have on average a lower body mass index (BMI) than non-smokers, it is of nowhere near sufficient magnitude to offset the risk of dying from cardiovascular disease as a result of smoking. The authors conclude that 'it is unquestionably better to quit smoking and gain weight than to continue to smoke.'169 p 834

Recent research has also found that while smokers tend to have a lower BMI than non-smokers, their fat distribution is more likely to be in the abdominal region (central adiposity or 'male pattern' fat distribution).15 Individuals with this pattern of fat distribution are at greater risk of developing a range of cardiovascular15 and metabolic problems related to obesity.170

The relationship between smoking and body weight is likely to be due to a range of effects of nicotine on the metabolism.171 Sustained cessation is associated with a mean weight gain of about 5–6 kilograms in the first year of abstinence,171, 172 an issue of concern to some smokers. For further discussion on implications for cessation, see Chapter 7, Section 7.7.7.4.

3.28.6 Mental illness

The prevalence of smoking is higher among people with psychiatric conditions.173–175 The reasons for this are complex and are discussed in greater detail elsewhere (Chapter 1, Section 1.10 and Chapter 9, Section 9.6), but one motivating factor for smoking is that tobacco may be regarded by some individuals as a way of relieving unpleasant symptoms of certain types of mental illness, and could therefore be seen as helpful.174

There is evidence that the action of nicotine in enhancing mood and concentration is more pronounced in some individuals with depression and cognitive problems (issues relating to mental awareness and judgement), and also that nicotine can help relieve unwelcome side effects from medication, particularly among patients being treated with antipsychotic drugs.174 These effects may occur because of different actions of nicotine on the brain chemistry reward system that have been observed in individuals with particular psychiatric conditions174 (see also Chapter 6, Section 6.3).

However, higher smoking rates among the mentally ill mean that they bear a disproportionate burden of morbidity and mortality from tobacco.176 Smokers with severe mental health illnesses have been identified in the Australian National Tobacco Strategy177 as requiring specialised strategies to assist in cessation. See also Chapter 7, Section 7.19.4.

3.28.7 Mouth ulcers

There is evidence that smokers178 and users of smokeless tobacco179 are less likely to develop aphthous stomatitis (common mouth ulcers). Transient increased incidence of mouth ulcers is commonly reported by individuals on quitting smoking.180

3.28.8 Thyroid cancer

Some studies have suggested that smoking may be associated with a reduced risk of developing thyroid cancer, particularly for women, but further research is required.15