Heart disease, coronary risk factors

Micha R, Mozaffarian D. Saturated fat and cardiometabolic risk factors, coronary heart disease, stroke, and diabetes afresh look at the evidence. Lipids. 2010, 45 893-905. 

Observational studies have suggested possible favourable effects of estrogen replacement therapy (ERT) on the risk of coronary heart disease in postmenopausal women. Since elevated plasma cholesterol has been identified as the primary risk factor for cardiovascular disease, investigations have focused on the inverse association between plasma cholesterol concentration and soy protein consumption. The cholesterol-lowering properties of soy have been demonstrated, and a good correlation has been found in... 

The effect of continuously administered low-dose 17-beta-estradiol (E2) + norethisterone acetate (NETA) on coagulation and fibrinolytic factors has been studied in 120 menopausal women, using two dosage variations (1 mg of E2 with 0.25 mg or 0.5 mg of NETA) compared with placebo over a year (53). In either dose, the combination significantly lowered plasma concentrations of factor VII, fibrinogen, antithrombin, and plasminogen activator inhibitor-1 (PAI-1) compared with placebo. These changes appear favorable, since they may lead to increased fibrinolytic activity and could reduce the risk of coronary heart disease. However, antithrombin activity was also reduced, which may increase the risk of venous thromboembolism. 

Many studies published during the last few decades have suggested that hyperhomocysteinemia is a risk factor for coronary artery disease (CAD), stroke, and thromboembolic disease. The Homocysteine Studies Collaboration metaanalysis of 30 studies concluded that elevated tHcy is a moderate risk factor for ischemic heart disease a level 3 xmol/L lower reduces the risk with an odds ratio of 0.89 (95% Cl = 0.83-0.96). The same was true for homocysteine as a risk factor for stroke (odds ratio = 0.81 95%5CI = 0.69-0.95) (6). A meta-analysis of 40 studies of the MTHFR 677 C > T polymorphism demonstrated a mildly increased risk of coronary heart disease with an odds ratio of 1. 16 (95% Cl = 1.05-1.28) (25). 

Body iron level and iron depletion play an important role in the gender differences seen in death from cardiac disease. There is a better correlation with heart disease mortality in iron levels compared with levels of cholesterol (5). It was found that risk of coronary heart disease (6) and carotid atherosclerosis (7) is associated with increased iron stores. However, impaired endothelium-derived nitric oxide activity may be without overt atherosclerosis in patients with risk factors and may be associated with the presence of atherosclerosis (4). Thus, endothelial dysfunction related to iron activity not only may be an early marker for cardiovascular risk but also may contribute to the pathogenesis of atherosclerosis (2) by the stimulation of low-density lipoproteins (LDL) and membrane lipid peroxidation (I) and may be a key to the understanding of early mechanism in the development of atheroma (7,8). Nakayama et al. (9) showed the role of heme oxygenase induction in the modulation of macrophage activation in atherosclerosis. However, Howes et al. (10) concludes that at the moment, the available evidence on iron hypothesis remains circumstantial. Moreover, Kiechl et al. (7) showed that the adverse effect of iron is hypercholesterolemia, In patients... 

Although most epidemiological studies on the relationships between plasma lipids and coronary heart disease have examined total plasma cholesterol (most of which is apoB-associated cholesterol) as a major risk factor, some case-control studies have shown that apoB-100 (i.e., apoB in LDL and VLDL) is higher in subjects with coronary heart disease than controls (A31, A32, F2, M34, 06, RIO, S43, V6, W14). It may be that apoB is itself a risk factor, and that a raised apoB concentration but normal LDL cholesterol will be a marker for a previously unsuspected group of people at risk from coronary heart disease (S43). An increasing body of evidence suggests that hyper-B-apoproteinemia may be an important risk factor for coronary heart disease. This evidence, and the possibility that apolipoprotein assays (in particular apoB and apoA-I assays) may serve as a better marker of risk for atherosclerosis than the standard lipid measurements, have been discussed by Brunzell et al. (B59). 

Rimm, E. B. (2000). Moderate alcohol intake and lower risk of coronary heart disease Meta-analysis of effects on lipids and homeostatic factors. Journal of the American Medical Association, 319, 152.3-1528. 

This British trial (Thrombosis Prevention Trial - TPT) [11] allocated 5,499 men with increased risk of coronary heart disease to either aspirin 75 mg daily or placebo, observing a 20% reduction of all coronary heart disease events (p = 0.04), almost entirely due to a 32% reduction in non-fatal events (p = 0.004). Diabetes was not one of the factors upon which baseline risk was calculated, and this probably explains why subsequent subgroup analyses of the trial results did not report separate data on diabetics... 

There is strong evidence that the risk of coronary heart disease is directly related to the plasma concentration of LDL-cholesterol and inversely related to that of HDL-cholesterol, and that the risk is reduced significantly by lowering elevated serum cholesterol levels. It has been known for many years that one of the most important dietary factors regulating serum cholesterol levels is the ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (SFA). The SFA increase and the PUFA decrease cholesterol levels, except for the trans PUFA, which have a similar effect to the SFA. A ratio of 0.5. 9 SFA PUFA is considered to be satisfactory. It is... 

Low levels of vitamin Bg may cause hyperhomocysteinaemia since vitamin Bg acts as a cofactor for tra .s-sulfation of cysteine (Siri et al. 1998). There is evidence that an elevated homocysteine level is a risk factor for heart disease and stroke. Endo et al. (2006) reported that vitamin Bg deficiency induced the oxidant stress which accelerates atherosclerosis. They also highlighted that the antioxidant activity of vitamin Bg may suppress the homo-cysteine-induced atherosclerosis. Vitamin Bg levels may be important in the prevention of coronary heart disease intake of vitamin Bg above the current recommended dietary allowance has been shown to be instrumental in the primary prevention of coronary heart disease among women (Rimm et al. 1998). 

It is a fallacy to believe that individuals with risk factors for cardiovascular events like smoking, hypertension, or hyperlipidemia can neutralize or minimize their adverse effects by exercise. In the Seven Countries Study (23,24), Finland had the highest overall prevalence of coronary heart disease. The Finnish population consumes large amounts of animal fat. Fiimish lumberjacks are an example of physically active people in whom the risk for coronary heart disease remains high (25). The approach to prevent coronary heart disease should be multifaceted... 

Fact Three major factors are associated with the risk of coronary heart disease namely, elevated blood pressure, cigarette smoking, and elevated serum cholesterol. A serum cholesterol level in excess of 280 mg/dl is considered a major risk for heart disease. The concentration of cholesterol in the blood is strongly affected by the degree of saturation of the dietary fat. 

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