Prevention of cardiovascular diseases: Role of exercise, dietary interventions, obesity and smoking cessation

Abstract

Hypertension, myocardial infarction, atherosclerosis, arrhythmias and valvular heart disease, coagulopathies and stroke, collectively known as cardiovascular diseases (CVDs), contribute greatly to the mortality, morbidity and economic burden of illness in Canada and in other countries. It has been estimated that over four million Canadians have high blood pressure, a comorbid condition that doubles or triples the risk of CVD. According to the Heart and Stroke Foundation of Canada, CVDs caused 36% of deaths in 2001 and were responsible for 18% of the total hospital costs in Canada. The majority of Canadians exhibit at least one CVD-related risk factor, such as tobacco smoking, physical inactivity, diabetes, obesity, hypertension, a lack of daily fruit and vegetable consumption, and psychosocial factors, making these people more prone to developing a serious CVD-related illness in the future. It is therefore important that CVD-related causes and concerns be addressed. Given the scope and prevalence of CVDs, it is obvious that a population health approach - 'prevention is better than cure' - would be the most appropriate model to adopt to deal with this ubiquitous health problem and to reduce the costs of hospitalization, long-term medication and rehabilitation. The focus of the present review is to evaluate and compare the results of epidemiological, experimental and clinical studies, reporting on the influence of physical activity, dietary intervention, obesity and cigarette smoking on cardiovascular health and the prevention of CVDs. The prophylactic measures must be dealt with collectively because there is overwhelming evidence that the occurrence of CVDs can be reduced by approximately 80% by making lifestyle modifications. The preventive strategies against CVDs must be targeted at a primary health promotion level before some of the important underlying causes of CVD seriously afflict a person or a population at large. Such preventive approaches would help in reducing not only employee absenteeism but also the hospital and drug costs burdening the health care systems of both developed and developing countries.

Keywords: Cardiovascular disease; Diabetes; Diet; Exercise; Obesity; Smoking cessation.

Figure 1)

Leading causes of death in Canada in 1999. Percentages represent data combined from males and females of all ages. CVD Cardiovascular disease; Dis Diseases; Infect Infectious. Data from reference

Figure 2)

Chemical structures of different fatty acids. Saturated fats contain no double bonds, monounsaturated fats contain one double bond and polyunsaturated fats contain two or more double bonds. Saturated fats tend to be solid at room temperature, whereas monounsaturated and polyunsaturated fats tend to be liquid at room temperature (128)

Figure 3)

Chemical structural differences between cis and trans fatty acids. Trans fatty acids rarely occur in nature, but are produced as a result of hydrogenation and fermentation, processes that saturate double bonds. The trans fats are hard for the body to metabolize and are responsible for causing atherosclerosis, heart disease, diabetes and obesity (36)

Figure 4)

Chemical structures of omega-3 and omega-6 polyunsatu-rated fatty acids

Figure 5)

Potential mechanisms by which dietary fibre may help in lowering plasma cholesterol. Fibre has a trapping and adsorbing action, which causes bile salts (taurocholic acid and glycocholic acid) to adhere to the rigid network. Bile acids are produced from cholesterol. When bile salts are trapped by dietary fibres and excreted into the feces, more cholesterol stores are mobilized to produce bile acids. To enable this process, the liver takes up more lipids from the blood to replenish cholesterol stores. The de novo synthesis of bile acids reduces serum lipid concentrations, causing an overall beneficial effect on cardiovascular health

Figure 6)

Resveratrol (RESV) has some chemical resemblance to the ovarian hormone 17-beta-estradiol (17β-E). The structural resemblance between 17β-E and RESV may explain the mild estrogenic activity of the latter. Such estrogenic activity may be responsible for the cardioprotective action of RESV (67)

Figure 7)

Diagram of the pathophysiological effects of cigarette smoking. The main biologically active ingredients in cigarette smoke are nicotine, carbon monoxide and various other oxidant gases. ↑ Increased; BP Blood pressure; CNS Central nervous system; HR Heart rate. Reproduced with permission from reference