The Fats of Life: Essential Fatty Acids in Health and Disease

7. Risk Factors in Cardiovascular Disease

88 There has been much made of the association between dietary saturated fats and high serum cholesterol levels, particularly LDL-cholesterol. Although high serum cholesterol was identified as a major risk factor for heart disease in the Framingham Heart Study, several international studies have not found a good correlation between serum cholesterol and death from all causes. Generally, there is a correlation between serum cholesterol and coronary death rate. It is important to keep in mind that the prevalence of death from coronary heart disease rises rapidly with age, particularly above seventy years of age. Often there is some correlation between death from all causes and serum cholesterol in younger populations (less than seventy years), as in the American and Finnish cohorts of the Seven Countries Study (Keys 1980, 124), but that correlation disappears as the cohort ages (Menotti et al. 2001). The American and Finnish cohorts had the greatest incidence of coronary deaths in the Seven Countries Study, which influenced the correlation between serum cholesterol and the allcause death rate in those groups. This chapter will look at a variety of other risk factors for heart disease, many of which appear to be much better predictors of heart attack than serum cholesterol. In many cases, these additional risk factors, such as inflammation, interact with high levels of LDL or serum cholesterol to produce oxidized LDL, which is responsible for atherogenesis. Some of these risk factors may promote erosion of atherosclerotic plaque, which leads to myocardial infarction, as described in the previous chapter. Inflammation as a Predictor of Heart Attack During the 1990s researchers found that a substance known as C-reactive protein (CRP) in the blood was much better than serum cholesterol levels as a predictor of heart attacks. Mark Pepys and colleagues at the Royal Free and University 7 Risk Factors in Cardiovascular Disease 88 RISK FACTORS IN CARDIOVASCULAR DISEASE 89 College Medical School in London found that heart attack patients who had high levels of CRP in the blood were much more likely to have a bad outcome than those with lower levels of CRP (Koenig and Pepys 2002). The Pepys group also showed there was a linear relationship between levels of CRP in blood and risk of heart disease. Paul Ridker and colleagues at Harvard Medical School in Boston found that blood CRP level was a useful predictor for first heart attack or stroke in patients, especially postmenopausal women, and that CRP and cholesterol levels were not related to one another; one could have high cholesterol and low CRP levels or vice versa (Willerson and Ridker 2004). It was also found that one of the benefits of daily aspirin was directly related to CRP and that statin drugs may, but do not necessarily, lower CRP levels. CRP levels are also linked to obesity (as measured by body mass index). If a person loses weight, the levels of CRP go down. CRP is also higher in people with type 2 diabetes, and high CRP levels have been associated with syndrome X (or metabolic syndrome), which increases risk of diabetes, myocardial infarction, and stroke (Willerson and Ridker 2004). Metabolic syndrome is characterized by the presence of excess abdominal fat, insulin resistance, increased blood pressure, and increased levels of glucose and triglycerides in the blood, as well as lower levels of HDL—in other words, an unhealthy state. Moderate physical activity is generally considered to be beneficial in reducing one’s risk of heart disease. It was found that participants in the ATTICA study in Greece who engaged in physical activity had significantly improved levels of many inflammatory risk factors relative to their sedentary counterparts. Exercisers exhibited a 29 percent decrease in CRP and 20 percent decrease in tumor necrosis factor-alpha (TNF-ƴ), while white blood cell counts of exercisers were only about one-fifth (19 percent) those of the sedentary group (Panagiotakos et al. 2005). Levels of TNF-ƴ and CRP were also found to be elevated in prehypertensive patients relative to individuals with normal blood pressure. Hypertension is another important risk factor in heart disease. Depression was also associated with both inflammation and thrombosis factors in people without active cardiovascular symptoms. Elevated inflammation indicators may explain the increased frequency of cardiovascular events in depressed individuals (Panagiotakos et al. 2004). A report from the Augsburg, Germany, cohort of the World Health Organization (WHO) MONICA project showed that interaction of high CRP levels and depressed mood in individuals resulted in a...