Effects of a low-energy diet associated with egg supplementation on plasma cholesterol and lipoprotein levels in normal subjects: results of a cross-over study

Lipoprotein metabolism in patients with anorexia nervosa: a case-control study investigating the mechanisms leading to hypercholesterolaemia

Hypercholesterolaemia is a common finding in patients with anorexia nervosa (AN). To investigate the type, frequency and pathophysiological mechanisms of changes in lipoprotein metabolism in AN we performed a cross-sectional study in fifty-eight female patients (mean age 24.2 years, BMI 15.3 (sd 1.5) kg/m(2)) and fifty-eight healthy age-matched controls (CO; BMI 22.2 (sd 1.7) kg/m(2)). Total cholesterol and LDL-cholesterol were higher in AN (5.5 (sd 1.3) v. 5.0 (sd 0.8) mmol/l, P=0.023; 3.6 (sd 1.1) v. 3.2 (sd 0.7) mmol/l, P=0.025 respectively). LDL particles were significantly more enriched in cholesterol and triacylglycerol in AN. In multiple regression analysis with LDL-cholesterol as the dependent and BMI, total body fat ( %), lathosterol:cholesterol ratio (endogenous cholesterol synthesis), 7alpha-hydroxy-4-cholesten-3-one (bile acid synthesis), non-esterified glycerol, free triiodothyronine and free thyroxine as independent variables, BMI was the only significant predictor in CO (R(2) 0.36, overall P=0.001). In AN the variability of LDL-cholesterol was significantly predicted by total body fat, free thyroxine, BMI, free triiodothyronine and non-esterified glycerol (R(2) 0.55, overall P<0.001). Subgroup analysis between restricting (AN-R) and binge-eating-purging patients (AN-B) indicated that in AN-R changes in lipoproteins, BMI and total body fat were more pronounced. AN-R patients had lower bile acid synthesis than AN-B (P=0.02). We conclude that elevated cholesterol concentrations in AN are generally due to an increase in LDL-cholesterol, which is mostly determined by the severe loss of body fat and the resulting changes in thyroid hormones, increased lipolysis and decreased endogenous cholesterol synthesis with resulting decrease in LDL removal. The clinical subtype of AN plays a major role in the mechanisms leading to hypercholesterolaemia.

[Atherosclerotic cardiovascular diseases, dyslipidemia, hypertension, obesity, and diabetes mellitus in a population of the metropolitan area of southeastern Brazil. I--Research methodology]

An epidemiological study was carried out into the risk factors for the following atherosclerotic cardiovascular diseases: lipemic disorders, obesity, hypertension, diabetes mellitus as related to some factors which characterize life-style (sedentary, drinking, smoking and eating habits). The population studied belongs to the metropolitan area of S. Paulo. The research project had the following objectives: a) the development of an epidemiological baseline for the study of the risk factors for the atherosclerotics cardiovascular diseases represented by the lipimic disorders, obesity, hypertension and diabetes mellitus and their relationship with personal, family and social characteristics; b) the for clinical-educative treatment of patients or people at risk. In view of the objectives above it was decided that the project should in an integrated way with the local health centers and community associations in the field work phase. For this purpose, the methodology adopted was that of establishing small geographical areas, denominated "study areas", in accordance with socioeconomic criterion. Clinico-biochemical and eating surveys were carried out and interviews held with a view to obtaining data on socioeconomic and demographic and life-style characteristics. The clinical survey collected data on anthropometric measurements, arterial pressure, electrocardiogram and symptoms of heart disease. The biochemical survey consisted of the measurement of the following constituents of the blood: total cholesterol, HDL cholesterol, triglyceride, magnesium, glucose, sodium, potassium and phosphorous. The eating survey covered data of historic food consumption. By means of indicators such as income, schooling, occupation, position held in the occupation, ownership of property and respective size of property and employment of labour, the social classes were established. The clinico-educative intervention was carried out in the following way: a) the team made contact with the community associations and the health centers, that begin to participate in the project, permitting the use of their physical space for the carrying out of surveys and clinical exams and taking part in the work of publishing and explaining the project; b) those individuals with positive diagnosis or who are found at risk were referred to the health centers which then include assistance for the diseases in question in their permanent activities. After the end the project the team gave to the community a report on the prevalence of the morbidities researched in their population.

Plasma lipoproteins in hyperlipidemic subjects eating iodine-enriched eggs

Iodine-enriched (IE) eggs are produced by chickens fed a diet containing kelp. These eggs have been reported to reduce plasma cholesterol in humans and experimental animals. The purpose of this study was to determine the effect of the ingestion of one IE egg/day on the plasma lipoprotein cholesterol in borderline and hyperlipidemic individuals ingesting a low-fat diet. One hundred three subjects with entry cholesterol levels greater than 5.17 mmol/L were placed on a low-fat, low-cholesterol diet for 12 weeks. Between weeks 4 and 12, approximately half of the subjects were randomly assigned to either a diet control group (n = 53), or a group who ingested one IE egg/day in addition to this diet (n = 50). Subjects in both the egg group and the diet control group had a significant reduction in total plasma cholesterol (TC) at the end of the study compared with study entry; addition of the egg in the diet did not abolish the TC reduction in the egg group. However, paired comparisons of total and lipoprotein cholesterol levels at the end of the egg intervention period with the end of the initial dietary period demonstrated that the egg group had a significantly greater increase than the diet control group in TC (egg group: 7.2 +/- 1.5% increase; diet controls: 1.5 +/- 0.9% increase; p less than 0.01) and low-density lipoprotein cholesterol (egg group: 9.2 +/- 1.7% increase; diet controls: 3.9 +/- 1.5% increase; p less than 0.01). This effect was most pronounced in subjects with higher initial cholesterol levels and subjects with mixed hyperlipidemia (elevated cholesterol and triglyceride). Results suggest that these particular groups of subjects are most susceptible to cholesterol changes associated with ingestion of IE eggs.

Dietary restriction amplifies the metabolic disturbances of very-low-density lipoproteins in cholesterol-fed rabbits

The effect of dietary restriction (half of the control ration) on VLDL turnover was investigated in cholesterol-fed rabbits. Rabbits on standard, cholesterol and restricted cholesterol diets were injected with homologous 125I-labelled VLDL. Accompanying the amplification of hypercholesterolemia, additional disturbances of VLDL turnover were observed when cholesterol feeding was associated with dietary restriction. Cholesterol-fed rabbits with normal caloric ration exhibited delayed clearance of 125I-labelled apolipoprotein B component of VLDL compared to control rabbits. This was markedly accentuated in underfed rabbits, indicating further down-regulation of apolipoprotein B,E receptors in these animals. Furthermore, a reduced proportion of radiolabelled apolipoprotein B was converted from VLDL to intermediate-density lipoprotein (IDL) and LDL in both groups receiving cholesterol-rich diets. Thus, the combination of further impairment in plasma clearance of VLDL and the poor conversion into IDL and LDL could account for the massive increase of beta-VLDL in underfed animals on cholesterol-rich diets.