Determinants of total and high density lipoprotein cholesterol in boys and men with special reference to diet

At present it is assumed that atherosclerosis begins in childhood and that this process may ultimately result in the manifestations of coronary heart disease later in life. For this reason it is relevant to study the distribution of risk indicators for coronary heart disease (CHD) in children from different countries and to seek possible determinants of these risk indicators.<p/>In Chapter 1 a general overview is given of coronary heart disease and its determinants. The reasons and objectives for research on CHD and the risk indicators for CHD are also discussed.<p/>In Chapter 2 the results are presented of a study on the distributions of mean total and HDL cholesterol concentrations in boys aged 7 and 8 years from urban and rural regions in 16 countries. A standardized protocol was used for the collection of samples with the analyses being carried out in one laboratory. The results of this study showed that the concentrations of total cholesterol in Dutch boys are similar to those of boys from Denmark, Austria, Ireland and Sweden but are lower than those of Finnish boys and higher than those of African and Asian boys. The mean concentrations of HDL cholesterol of the boys appeared to increase linearly with that of total cholesterol. This would indicate that both the concentrations of total and HDL cholesterol increase under the influence of a westernized diet. It would also indicate that the mean concentration of HDL cholesterol would be positively related to the incidence of coronary heart disease when different populations are compared, provided that the findings in boys could be extrapolated to adults.<p/>Chapter 3 deals with the concentrations of total and HDL cholesterol in two age-categories of adult men from thirteen countries. The concentrations of total and HDL cholesterol were on average higher in the groups of men from the European countries than in those from Asia and Africa. Although the tendency for a concomitant increase of mean HDL cholesterol and total cholesterol concentrations was less clear in the adult men than it was in the boys, there was no tendency for lower HDL cholesterol concentrations in men with higher total cholesterol concentrations. The body mass index appeared to be positively related with the concentrations of total cholesterol and negatively with that of HDL cholesterol.<p/>Chapter 4 deals with the concentrations <em>of</em> total and HDL cholesterol in macrobiotic, vegetarian and non-vegetarian men and boys. The concentrations of both total and HDL cholesterol were lower in the macrobiotic men and boys than in the other groups except for the concentration of HDL cholesterol in the non-vegetarian men. The variation between groups in the concentration of HDL cholesterol appeared to be largely due to variations in the concentration of cholesterol in the HDL <sub><font size="-1">2</font></sub> fraction (1.063 < ρ <sub><font size="-1">20</font></sub> < 1.125).<p/>In Chapter 5 the results are described of a more in depth study on the determinants of total and HDL cholesterol in boys from Finland, the Netherlands, Italy, the Philippines and Ghana. Positive correlations were found between the intake of fat, saturated fatty acids, monounsaturated fatty acids and dietary cholesterol and the concentrations of total and HDL cholesterol within several groups. Using the regression coefficients from a multiple regression analysis on the pooled data, it could be calculated that on average 24 percent of the inter-country differences in the levels of total cholesterol is explained by differences in the intakes of saturated fatty acids. Differences between the groups of the different countries 'in the intakesof carbohydrate explained on average 29 percent of the differences in the concentrations of HDL cholesterol. The results support the hypothesis that higher concentrations of total and HDL cholesterol are associated with western types of diets which are rich in saturated fatty acids and relatively poor in complex carbohydrates.<p/>Chapter 6 contains a general discussion of the various studies. The main conclusions were the following:<br/>- young boys from countries like Finland, the Netherlands, Denmark, Austria and Sweden are likely to be at a higher risk of developing coronary heart disease than boys from Greece or Portugal and boys from Asian and African countries;<br/>- the negative relationship between HDL cholesterol concentration and mortality or incidence from coronary heart disease as found within populations is not incompatible with the absence of a negative or even the presence of a positive relationship between HDL cholesterol and mortality from coronary heart disease when different countries are compared;<br/>- the changes induced by diet in the concentrations of total and HDL cholesterol tend to be parallel;<br/>- high concentrations of HDL cholesterol associated with a high intake of animal fat probably reflect a higher capacity to handle large amounts of dietary fat;<br/>- low concentrations of HDL cholesterol associated with a high intake of animal fat probably reflect a lower capacity to handle large amounts of dietary fat or when associated with a low intake of fat a normal capacity to handle dietary fat;<br/>- diets with relatively high proportions of food from vegetable origin, especially those relatively rich in complex carbohydrates and relatively poor in saturated fat, together with a considerable proportion of physical activity and an optimum level of body fatness might be beneficial for the prevention of the development of atherosclerosis in childhood.<p/>Thus it has been shown that epidemiological studies can play an important role in elucidating the relationship between diet and coronary heart disease. In particular, it has been possible to develop hypotheses on the significance of the concentration of HDL cholesterol as a risk factor for coronary heart disease