HOW TO PREVENT CORONARY HEART DISEASE WITH DIETARY

Аннотация

Coronary heart disease (CHD) remains the leading cause of mortality in industrialized countries and is rapidly becoming a primary cause of death worldwide. Thus, identification of the dietary changes that most effectively prevent CHD is critical. Key words: unsaturated, saturated, trans-fats, lipoprotein, low-density lipoprotein, carbohydrates, fatty acids. КАК ПРЕДОТВРАТИТЬ ИШЕМИЧЕСКУЮ БОЛЕЗНЬ СЕРДЦА С ПОМОЩЬЮ ДИЕТЫ Аннотация. Ишемическая болезнь сердца (ИБС) остается основной причиной смертности в промышленно развитых странах и быстро становится основной причиной смерти во всем мире. Таким образом, определение изменений в питании, которые наиболее эффективно предотвращают ИБС, имеет решающее значение. Ключевые слова: ненасыщенные, насыщенные, трансжиры, липопротеины, липопротеины низкой плотности, углеводы, жирные кислоты. Compelling evidence from metabolic studies, prospective cohort studies, and clinical trials in the past several decades indicates that at least 3 dietary strategies are effective in preventing CHD: substitute non hydrogenated unsaturated fats for saturated and trans-fats; increase consumption of omega-3 fatty acids from fish, fish oil supplements, or plant sources; and consume a diet high in fruits, vegetables, nuts, and whole grains and low in refined grain products. However, simply lowering the percentage of energy from total fat in the diet is unlikely to improve lipid profile or reduce CHD incidence. Substantial evidence indicates that diets using non hydrogenated unsaturated fats as the predominant form of dietary fat, whole grains as the main form of carbohydrates, an abundance of fruits and vegetables, and adequate omega-3 fatty acids can offer significant protection against CHD. Such diets, together with regular physical activity, avoidance of smoking, and maintenance of a healthy body weight, may prevent the majority of cardiovascular disease in Western populations. Until recently, most epidemiologic and clinical investigations of diet and CHD have been dominated by the diet-heart hypothesis. 1172 ResearchBib IF - 11.01, ISSN: 3030-3753, Volume 2 Issue 2 However, the original hypothesis was overly simplistic because the effects of diet on CHD can be mediated through multiple biological pathways other than serum total cholesterol or low-density lipoprotein cholesterol. Numerous controlled feeding studies of the effects of different dietary fatty acids on serum cholesterol levels have been summarized in several meta-analyses from which predictive equations have been developed. All such analyses confirm early reports by Keys and Hegsted that saturated fatty acids increase and polyunsaturated fatty acids decrease total and LDL cholesterol. All 3 classes of fatty acids (saturated, monounsaturated, and polyunsaturated) elevate high-density lipoprotein cholesterol (HDL-C) when they replace carbohydrates in the diet, and this effect is slightly greater with saturated fatty acids. Also, triglyceride levels increase when dietary fatty acids are replaced by carbohydrates. Because replacement of saturated fat with carbohydrates proportionally reduces both LDL-C and HDL-C, and, thus, has little effect on the LDL-HDL ratio and increases triglycerides, this change in diet would be expected to have minimal benefit on CHD risk. However, when monounsaturated or polyunsaturated fats replace saturated fat, LDL-C decreases and HDL-C changes only slightly. Moreover, substituting polyunsaturated fat for saturated fat may have beneficial effects on insulin sensitivity and type 2 diabetes. In numerous controlled metabolic studies, trans-fatty acids (found in stick margarine, vegetable shortenings, and commercial bakery and deep-fried foods) have been shown to raise LDL-C levels and lower HDL-C relative to cis-unsaturated fatty acids, and the increase in the ratio of total to HDL cholesterol for trans-fat is approximately twice that for saturated fat . Trans-fat increases plasma levels of lipoprotein and triglycerides and may reduce endothelial function by impairing flow- mediated dilation. In addition, trans-fatty acids adversely affect essential fatty acid metabolism and prostaglandin balance by inhibiting the enzyme delta-6 desaturase. Finally, high intake of trans-fat may promote insulin resistance and increase risk of type 2 diabetes. Only a handful of dietary trials with CHD end points have been conducted and most were among patients with CHD. Two dietary approaches were tested in earlier trials; one replaced saturated fat with polyunsaturated fat, leaving total fat unchanged; the other lowered total fat. In all the high- polyunsaturated-fat trials, serum cholesterol was significantly reduced. In the Finnish Mental Hospital Study, soft margarine replaced stick margarine, so the reduction in CHD was probably in part due to reduction in trans-fat intake. In the Minnesota Coronary Survey, cardiovascular events were not significantly reduced by a high-polyunsaturated-fat diet despite a decrease in ser