Influence of weight reduction on plasma high-density-lipoprotein cholesterol concentrations in severe obesity: interrelationships with plasma insulin levels.

The influence of caloric restriction and of weight loss during a weight-maintaining diet on lipid profile and in particular on high density lipoprotein (HDL) is controversial. In this study we analyzed the effect of a period of very low caloric diet (VLCD) and of a period of hypocaloric diet followed by 30 days of weight stabilization on lipoprotein levels, especially on HDL cholesterol and its subfractions (HDL2 and HDL3) and on the summated means of glucose (sigma glucose) and insulin levels (sigma IRI) after an oral tolerance test in a group of obese females. Body weight decreased significantly during the VLCD and hypocaloric diet. Total cholesterol decreased significantly after the VLCD and hypocaloric diet, but after the period of the weight-maintaining diet it was superimposable to the initial value. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol behaved like total cholesterol. HDL2, HDL3 and HDL cholesterol decreased significantly after the period of VLCD. Then, after the hypocaloric diet the values of HDL2, HDL3 and HDL cholesterol returned towards the initial values and only after the period of the weight-maintaining diet did their values increase significantly. sigma glucose did not vary significantly at any time of the study, while sigma IRI reduced significantly both after the hypocaloric diet and the weight-maintaining diet. HDL2 and HDL cholesterol changes were found to be positively correlated to the variations of sigma IRI both at day 45 and 75 of the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hydrophobic surfactant inhibits hypercholesterolemia in pair-fed rabbits on a cholesterol-free, low-fat diet

Poloxalene, a hydrophobic surfactant, is known to prevent hypercholesterolemia in animals fed a high-fat, high-cholesterol diet. It has not been demonstrated, however, whether this agent is of benefit when hypercholesterolemia is induced in animals by means other than the feeding of a high-fat diet. In this study, hypercholesterolemia was produced in rabbits by feeding a low-fat, cholesterol-free diet with dietary protein supplied by casein for a period of 8 weeks. Controls were given this diet without poloxalene and experimentals were given the diet with poloxalene. Total serum cholesterol levels increased in both groups, but the rise was greater for the control group. Lipoprotein analysis performed at the conclusion of the study showed significantly greater low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels in the control group as compared to the experimental group. Total protein and apolipoprotein B (apo B) were also greater in control LDL. It was concluded that poloxalene favorably affects this model of hypercholesterolemia as total serum cholesterol, LDL cholesterol, and LDL apo B were all less and the HDL cholesterol to LDL cholesterol ratio was higher in surfactant-treated rabbits.     

Effects of hypocaloric dietary treatment enriched in oleic acid on LDL and HDL subclass distribution in mildly obese women.

OBJECTIVE: To study the effects of a carbohydrate-enriched (HiCarbo) or olive-oil-enriched (HiMUFA) hypocaloric diet on plasma lipoprotein levels and physical properties. DESIGN: A six-month follow-up dietary intervention study with a HiCarbo diet providing 60% of total calories as complex carbohydrates, 15% as proteins and 25% as fats [10% saturated (SFA); 7% monounsaturated (MUFA); 8% polyunsaturated fatty acids (PUFA)]; or a HiMUFA diet with 40% complex carbohydrates, 15% proteins and 45% fats (10% SFA; 27% MUFA; 8% PUFA). SUBJECTS: Twenty consecutive, mildly obese, normolipidemic premenopausal women (11 on HiCarbo and nine on HiMUFA diets) and 14 age- and sex-matched, lean controls. MEASUREMENTS: Body mass index (BMI), waist/hip ratio, plasma lipoproteins, apolipoprotein (apo) AI and B, LDL and HDL density distribution, and phospholipid fatty acid composition at baseline, and after 3 and 6 months on dietary treatment. RESULTS: Body weight progressively decreased during the first 3 months and then it stabilized during the following 3 months (-11% vs. baseline in both groups; P < 0.01). LDL-Cholesterol decreased significantly in both groups. HDL-Cholesterol increased significantly in the HiMUFA group, whereas a decreased level was observed in the HiCarbo group. At baseline the obese women had higher very low density lipoprotein (VLDL) and dense LDL-Cholesterol, and lower HDL2 cholesterol levels than the controls; these abnormalities persisted in the HiCarbo diet, whilst a significant decrease in the dense LDL associated with an increase in the HDL2 cholesterol was seen in the HiMUFA diet. HDL3 was not affected by either diet. The LDL/HDL-Cholesterol ratio was not affected by the HiCarbo diet, whilst it was significantly reduced after 6 months of HiMUFA diet as compared with baseline. Apo AI increased in the HiMUFA group, and decreased in the HiCarbo group. CONCLUSIONS: Both diets were effective in decreasing body weight. At steady weight conditions, only the HiMUFA diet improved LDL and HDL subclass distribution abnormalities present in mildly obese normolipidemic women.     

Serum lipids, lipoprotein composition and liver cholesterol in genetically obese Zucker rats fed semipurified diets containing either casein or soy protein

The effect of semipurified diets containing either casein or soy protein on serum lipids, lipoprotein composition and liver cholesterol was studied in genetically obese Zucker rats. The ingestion of a cholesterol-enriched semipurified diet containing casein resulted in elevated levels of serum cholesterol and phospholipids compared to the feeding of a soy protein diet. No differences in serum triglycerides were observed. Differences in serum cholesterol and phospholipids were mainly reflected in the very low density lipoproteins and low density lipoproteins and to a minor extent in the high density lipoproteins. Liver cholesterol paralleled the levels of cholesterol in the serum, the rats fed casein exhibited markedly higher levels of liver cholesterol than those fed soy protein. Furthermore, the rats fed casein also had enlarged livers. Thus, this study clearly shows the differential cholesterolemic effect of dietary casein and soy protein in genetically obese Zucker rats.     

Intermediate density lipoprotein-apolipoprotein B turnover in rabbits fed semipurified diets containing casein or soy protein

The aim of this study was to investigate the underlying causes of elevated levels of intermediate density lipoprotein (IDL) in rabbits fed casein compared to soy protein in a cholesterol-free, semipurified diet. Kinetic studies were carried out in which homologous, radiolabelled IDL was injected into casein- and soy protein-fed animals after a period of 7 months on diet. Total plasma cholesterol and IDL cholesterol and protein were significantly higher in animals fed casein compared to those fed soy protein. The fractional catabolic rate of IDL-apolipoprotein B was significantly lower in casein-fed animals but the difference in mean values for the production rate did not reach statistical significance. The effect of feeding casein on IDL can be attributed to its reduced efficiency of removal from the plasma.     

Compositional changes in serum lipoproteins during developing hypercholesterolemia induced in rabbits by cholesterol-free, semipurified diets

Changes in the concentration and composition of serum very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) were studied in rabbits transferred from chow diet to cholesterol-free, semipurified diets containing casein or isolated soy protein. The fat and fibre content of these diets was similar to that of chow but a higher protein level was used to enhance the hypercholesterolemia. During the first week on the casein diet, there was a marked increased in LDL-cholesterol, protein and phospholipids, and these higher levels were maintained during the subsequent 3 weeks of the study. Similar but less marked changes were obtained with the soy protein diet. The components of VLDL showed relatively little change after introduction of the diets to the animals. In both VLDL and LDL, the proportion of cholesterol increased and that of triglycerides decreased after 1 week on the casein diet and a similar trend was seen in HDL. The concentration of HDL-cholesterol showed little change but triglycerides, protein and phospholipids all tended to decline on both casein and soy protein diets.     

Influence of fish protein as compared to casein and soy protein on serum and liver lipids, and serum lipoprotein cholesterol levels in the rabbit

Serum and hepatic cholesterol and triglyceride levels, and serum lipoprotein cholesterol were investigated in rabbits fed fish protein as compared to casein and soy protein as part of a 20% protein, low fat, cholesterol-free, semi-purified diet. A nonpurified diet was used as a control. After a 28-day experimental period, rabbits fed casein developed hypercholesterolemia compared to those fed the soy protein diet. Serum cholesterol levels of rabbits fed fish protein was intermediate and not different from that of the casein or the soy protein group. However, serum triglycerides were higher in the fish group than in the casein group. Feeding of fish protein resulted in a reduction of hepatic cholesterol compared to casein, indicating no direct relationship between serum and hepatic cholesterol. In addition, fish protein induced a decrease of cholesterol in the low density lipoproteins (LDL) compared to casein and an increase of cholesterol in the high density lipoproteins (HDL) compared to casein and soy protein. Reduction in LDL-cholesterol (LDL-C) and elevation in HDL-cholesterol (HDL-C) caused a 10-fold decrease in the LDL-C/HDL-C ratio of fish protein fed rabbits compared to those fed casein. This ratio was similar to that observed with soy protein which was also lower than the ratio of the casein group. Thus, since the LDL-C/HDL-C ratio has been shown to be a good indicator of the atherosclerosis risk, these results suggest that fish protein, as well as soy protein, may reduce the risk of atherosclerosis in rabbits, compared to casein.     

Effects of cholesterol-free, semipurified diets containing different levels of casein or soy protein on distribution of cholesterol and protein among serum lipoproteins of rabbits

Rabbits fed cholesterol-free, low-fat, semipurified diets have more cholesterol and protein in serum low density lipoprotein (LDL) relative to high density lipoprotein (HDL) than rabbits fed Chow diet. This difference was accentuated by a casein semipurified diet but was also observed with a soy protein diet even though the latter did not produce an elevation of serum cholesterol. To investigate the reason for these differences, the formulation of the semipurified diets was altered by reducing the level of protein from 27 to 16%, increasing the fat from 1 to 4% and the fiber from 5 to 13%, to correspond more closely to the proportions in Chow. With this formulation, the soy protein diet gave a lipoprotein pattern similar to that of Chow, whereas the casein diet produced a moderately elevated serum cholesterol level with more cholesterol in LDL than in HDL. When the protein in the newly formulated diets was increased back to 27%, the lipoprotein patterns reverted to those obtained with the original formula. In this case, soy protein-fed rabbits had moderately elevated serum cholesterol whereas casein-fed animals showed hypercholesterolemia. These results indicate that the altered lipoprotein pattern observed previously in rabbits fed semipurified diets is related to the high level of protein in those diets.     

Serum leptin, oxidized low density lipoprotein and plasma asymmetric dimethylarginine levels and their relationship with dyslipidaemia in adolescent girls with polycystic ovary syndrome

OBJECTIVE: The aim of this study was to investigate serum leptin, oxidized low density lipoprotein (ox-LDL) and asymmetric dimethylarginine (ADMA) levels and their interaction with dyslipidaemia in adolescents with polycystic ovary syndrome (PCOS). PATIENTS AND DESIGN: The study group consisted of 23 obese (obPCOS) and 21 nonobese girls with PCOS (nPCOS), and 31 lean healthy controls. PCOS was defined by the National Institutes of Health (NIH) criteria as the presence of chronic oligoanovulation and hyperandrogenism. Fasting leptin, ox-LDL, ADMA and detailed lipid-lipoprotein profile were determined. Atherogenic index (AI) was calculated as [Total cholesterol - HDL cholesterol/HDL cholesterol]. Logarithmic transformations were made for ox-LDL. RESULTS: Total cholesterol, triglycerides, LDL cholesterol, very low density lipoprotein (VLDL) cholesterol, apolipoprotein B, lipoprotein A levels and AI were higher and apolipoprotein AI was lower in obPCOS compared to those in controls (P < 0.05). LDL cholesterol, apolipoprotein B and lipoprotein A levels were higher in nPCOS compared to controls (P < 0.05). ADMA and ox-LDL levels did not differ in the three groups. Leptin was significantly higher in obPCOS compared with that in the other two groups (P < 0.001) and it was correlated with triglycerides (r = 0.62), VLDL cholesterol (r = 0.45), lipoprotein A (r = 0.38) and AI (r = 0.43) in the PCOS group (P < 0.05). CONCLUSION: Our data demonstrate that ADMA and ox-LDL levels in adolescent PCOS subjects were not different than those in controls. Abnormal lipid profile was shown in obese and nonobese girls with PCOS and leptin was related with these lipid abnormalities in the PCOS subjects.     

Plasma lipid and lipoprotein cholesterol levels in swine. Modification of protein-induced response by added cholesterol and soy fiber

Piglets, aged 8 weeks and weighing 12-18 kg, were fed semi-purified casein or soy protein diets, with or without cholesterol and soy hull fiber, for 2 months. In addition to observing the effects of the dietary treatments on growth, the modification of the primary hypocholesterolemic action of soy protein by cholesterol and soy fiber was studied. Pigs fed the soy protein or casein diets grew normally with no difference in weight gain. Plasma triglyceride and phospholipid levels, as well as several plasma metabolic indices examined, were not significantly affected by dietary treatment. However, plasma total cholesterol was higher (but not significantly) in pigs fed casein than in those fed soy protein alone. Cholesterol feeding induced markedly significant (P less than 0.05) hypercholesterolemia with either protein source, compared to feeding the proteins without added cholesterol. Dietary soy fiber fed simultaneously with cholesterol decreased the cholesterol-induced hypercholesterolemia, but the reduction was significantly greater (P less than 0.05) with soy protein than with casein in the diet. Analyses of the lipoprotein cholesterol indicated that LDL cholesterol was much more sensitive to the changes induced by feeding cholesterol and soy fiber than either HDL or VLDL cholesterol. These findings suggest a beneficial role of dietary soy fiber in hypercholesterolemia.     

The effect of dietary casein and soy protein on cholesterol and very low density lipoprotein metabolism in the rat

Rats fed a high-cholesterol semipurified diet containing casein developed higher levels of serum cholesterol than soy-fed animals. The hypercholesterolaemia of casein-fed rats was due to accumulation of very low density lipoproteins (VLDL), as measured by increased concentrations of serum VLDL cholesterol, protein and apoprotein B. High density lipoprotein (HDL) cholesterol was similar for the two dietary groups. Cholesterol absorption, as measured by the dual isotope ratio method and by direct measurement of cholesterol secretion into thoracic duct lymph, did not differ between the two groups. Cholesterol kinetics were derived from plasma cholesterol specific radioactivity curves and the casein-fed rats had a similar rate of plasma cholesterol production, but a significantly lower plasma cholesterol fractional catabolic rate (FCR) compared with the soy-fed rats. Kinetics of plasma VLDL apoprotein B, derived from analysis of reinjected 125I-labelled VLDL protein, also showed a lower fractional catabolic rate with casein feeding. This suggests that the accumulation of VLDL in the plasma of rats fed dietary casein is not due to excess VLDL production but to deficient VLDL removal. The hypercholesterolaemia appears to be a consequence of diminished VLDL catabolism.     

Long-term effects on lipid metabolism of weight reduction on lactovegetarian and mixed diet

The effects of two dietary weight reduction programmes (1200 kcal/day) on lipid metabolism were followed for one year in moderately obese subjects. The groups consisted of lactovegetarian (n = 31), mixed diet (n = 37) and control (n = 42) groups. Serum triglyceride levels decreased rapidly during the first two weeks (46 per cent on average) especially in the mixed diet group, and this change was still statistically significant at 6 and 12 months after the beginning of the study. Serum total cholesterol levels also decreased rapidly in the beginning, but at 6 and 12 months the change was no longer statistically significant. After a small initial decrease HDL cholesterol levels appeared to increase towards the end of the study year. This increase was more marked in men (18.6 per cent at 6 months) than in women, and in the mixed diet group than in the lactovegetarian group (P less than 0.05 between the groups). The HDL/total cholesterol ratio increased rapidly in the beginning of the weight reduction and practically remained at the elevated (12-16 per cent) level during the whole follow-up. This increase was also more apparent in men than in women, and in the mixed diet group than in the lactovegetarian group. The changes in HDL subfractions, HDL2 and HDL3, paralleled those seen in the HDL cholesterol levels. Similarly the alterations in apolipoproteins A-I and B resembled those of the HDL and total cholesterol levels. The activity of adipose tissue lipoprotein lipase decreased drastically (about 50 per cent) at the beginning of the weight reduction, while at 6 and 12 months the mean activities were higher than the initial levels. This was also seen in the LPL activity when measured in post-heparin plasma. The activity of post-heparin plasma hepatic lipase decreased clearly at both 6 (P less than 0.001) and 12 months (P less than 0.01) in the mixed diet group, whereas no change was found in the lactovegetarian group. The ratio of subscapular to triceps skinfold reduced significantly (P less than 0.01) in women but not in men during the intervention period. Our study shows that in moderately overweight subjects weight reduction with the aid of a low-calorie dietary programme results in favourable responses in lipid metabolism many months after the cessation of the weight reduction programme. These responses appear to be stronger in subjects following mixed diet than in those attempting to follow a lactovegetarian diet.     

Influence of 4 weeks' intervention by exercise and diet on low-density lipoprotein subfractions in obese men with type 2 diabetes.

Insulin resistance is associated with dyslipoproteinemia characterized by increased serum triglycerides, reduced high-density lipoprotein 2 (HDL2) cholesterol, and increased small, dense low-density lipoprotein (LDL) subfraction particles. Physical activity and weight reduction are known to improve insulin resistance and dyslipoproteinemia, but their influence on LDL subfractions in diabetic patients is unknown. Therefore, we investigated the effect of a 4-week intervention program of exercise (2,200 kcal/wk) and diet (1,000 kcal/d: 50% carbohydrate, 25% protein, and 25% fat; polyunsaturated/saturated fat ratio, 1.0) on glycemic control and HDL and LDL subfractions in 34 obese patients with non-insulin-dependent diabetes (age, 49 +/- 9 years; body mass index [BMI], 33.1 +/- 5.1 kg/m2). Reductions in body weight (P < .001) and improvements in fasting blood glucose, insulin, fructosamine (P < .001), and free fatty acids (P < .01) by intervention were associated with reductions in serum cholesterol and apolipoprotein B (apo B) concentrations in very-low-density lipoprotein (VLDL) (P < .01), intermediate-density lipoprotein (IDL), and small, dense (>1.040 g/mL) LDL particles (P < .001). These data underlie the positive influence of weight reduction induced by exercise and diet on insulin resistance and lipoprotein metabolism in obese diabetic patients, particularly showing improvements of the LDL subfraction profile with a decrease of small, dense LDL particles. This is of particular importance, as these particles have been shown to be associated with coronary artery disease.     

Cholesterol-lowering and HDL-raising properties of lecithinated soy proteins in type II hyperlipidemic patients

Plasma lipoprotein changes were evaluated in 65 type II patients undergoing sequential 4-week dietary treatments with: (I) standard low-lipid diet; (II) low-lipid diet with total replacement of animal proteins with textured soy proteins containing 6% of lecithin (L-TVP); (III) standard low-lipid diet; (IV) low-lipid diet with a 50% substitution of animal proteins with L-TVP. Total cholesterolemia was significantly reduced in both periods of L-TVP administration: -18.6% during phase II (total replacement) and -13.2% during phase IV (partial replacement). High-density lipoprotein (HDL) cholesterol levels tended to increase during L-TVP administration. However, only patients in the mid- and low tertiles for HDL cholesterolemia showed a significant increase of HDL levels during L-TVP. This 'normalizing' activity of L-TVP on plasma lipoproteins, even when administered as a partial dietary substituent, may be of clinical interest for subgroups of patients at high vascular risk.     

Effects of soy protein and casein in low cholesterol diets on plasma lipoproteins in normolipidemic subjects

Dietary plant proteins may lower plasma cholesterol and LDL concentrations in hypercholesterolemic patients when substituted for animal proteins, particularly in diets with low cholesterol and saturated fat content. Plant protein diets appear, however, to be without effect on plasma lipoprotein levels in normal subjects. In the present study, we have examined whether the origin of the dietary protein, i.e. plant (soy) or animal (casein), affects the plasma lipoproteins in normolipidemic subjects when these proteins are presented as components of diets low in cholesterol and saturated fat. The study followed a crossover design. Five men and 5 women consumed liquid formula diets containing 20% of calories as casein or soy protein, 28% as fat (mainly monounsaturated), and 52% as carbohydrate; the intake of cholesterol was less than 100 mg per day. The two dietary periods, each of 1 month duration, were separated by an interim period of 1 month on self-chosen food. Following an initial 30% reduction of cholesterol and LDL plasma levels on both diets, the concentrations of each of the major lipoprotein classes (VLDL, IDL, LDL, HDL2 and HDL3) were similar during the two experimental dietary periods. Body weights were essentially constant. Dietary soy protein and casein could not be distinguished in their effects on the plasma concentrations and chemical composition of the major lipoprotein classes in normolipidemic subjects.     

Effects of an aerobic exercise program and diet on body composition and cardiovascular function in obese persons

The purpose of this study was to determine the effect of a combination of aerobic exercise and hypocaloric diet on body composition, cardiovascular function and some cardiovascular risk factors in obese patients. Ten subjects, (8 women 2 men X age 30 years and 138% of ideal body weight) volunteered as participants. The program lasted 12 weeks and consisted of a hypocaloric diet (1257 kcal/day) and 3-5 days/week supervised sessions of aerobic exercise (65-90% maximal heart rate and/or 50-80% of maximal oxygen uptake). The program resulted in a significant mean decrease in body weight of 7.7 kg. for the group (P less than or equal to 0.05). Mean (+/- EE) relative body fat significantly decreased from 35.9 +/- 2 to 31.6 +/- 2%. Interestingly, the decrease in relative body fat was solely accounted for by a significant decrease in fat weight, as body free of fat remained constant. Cardiovascular function as evidenced by oxygen uptake, increased 11.3%. Resting systolic and diastolic blood pressure fell significantly from 131/90 +/- 8/9 to 115/76 +/- 2/1 mmHg. Total cholesterol significantly dropped from a mean value of 247 +/- 24 to 183 +/- 20 mg/100 ml (P less than 0.05). Triglycerides significantly decreased from 212 +/- 32 to 45 +/- 10 mg/100 ml (P less than 0.05). It was concluded that a combination of aerobic exercise and hypocaloric diet can favorably improve body composition, cardiovascular function and cardiovascular risk factors.     

Plasma lipoproteins and lipase and lecithin:cholesterol acyltransferase activities in obese subjects before and after weight reduction

Plasma lipoprotein concentrations and post-heparin lipoprotein lipase, hepatic triglyceride lipase (HTGL), and lecithin:cholesterol acyltransferase (LCAT) activities were determined in 10 obese women before and after weight loss. In period I, a diet was given to maintain constant weight for 3 weeks. In period II, total calories were restricted to 600 kilocalories/day for 3 weeks. In period III, caloric intake was adjusted to maintain weight at the lower level for 6 weeks. The lower calorie diet decreased plasma very low density, low density, and high density lipoprotein (HDL), cholesterol, and apolipoprotein B and A-I concentrations and molar enzyme activities, while the percent conversion of free to esterified cholesterol by the LCAT enzyme was unchanged. During weight stabilization at a lower state (period III), the mean plasma HDL cholesterol level increased, and lipoprotein lipase and LCAT activities increased to values higher than those in period I. The mean HTGL activity remained reduced. I conclude that successful weight loss improves the possibly atherogenic plasma lipoprotein profile of obese subjects. The increase in HDL cholesterol and cholesterol esterification, possibly explained by lowered HTGL enzyme activity, may increase the capacity of HDL to transport cholesterol from peripheral cells to the liver.     

Gelatin intake increases the atheroma formation in apoE knock out mice

The effect of gelatin ingestion on cholesterol metabolism and on atheroma formation was evaluated in both wild type (n=14) and apoprotein E (apoE) knock out (apoE(-/-)) (n=20) C57BL/6 7-week-old mice. Animals were fed a cholesterol-free isoproteic semi-purified diet containing 20% of casein (control diet) or 10% of casein plus 10% of gelatin (gel diet) for 8 weeks. In wild type mice, dietary gelatin caused a reduction in the serum triacylglycerols levels associated with an increase in the fecal excretion. No difference in blood cholesterol was seen at the sixth week of experiment. At the eighth week of experiment, there was a modest but significant reduction of serum total and high density lipoprotein (HDL) cholesterol in apoE(-/-) mice fed on gel diet compared to the control. Total cholesterol/HDL cholesterol ratio was 2-fold higher in the gel group than that seen in the control group (14.39 and 7.84, respectively). Histological analyzes showed a 2.2-fold increase in the dimension of the atherosclerotic plaques in the proximal aorta in apoE(-/-) mice fed on a gel diet compared to those fed on a control diet. The gel diet also promoted a reduction in the fecal excretion of bile acids. Hepatic cholesterol was similar in both groups. In conclusion, although gelatin reduced total serum cholesterol, this reduction was associated to a decrease of HDL cholesterol and consequent increase of total cholesterol/HDL cholesterol ratio, resulting in an acceleration of atherogenesis.     

Changes in plasma lipids and uric acid with sodium loading and sodium depletion in patients with essential hypertension

The short-term effects of manipulating dietary salt intake on plasma levels of cholesterol, lipoproteins and uric acid were studied in two groups of patient with essential hypertension. With dietary salt restriction in 8 patients (10 g to 2 g salt/day for five days), plasma total cholesterol, esterified cholesterol, beta-lipoprotein, low density lipoprotein and uric acid rose significantly. With salt repletion (2 g salt/day to 20 g/day for five days) in 17 patients, plasma total cholesterol, esterified cholesterol, beta-lipoprotein, low density lipoprotein and uric acid fell significantly. Total/HDL cholesterol ratio increased significantly with salt restriction and decreased significantly with repletion. However, very low density lipoprotein, HDL-cholesterol, triglyceride, phospholipid, chylomicron and non-esterified fatty acid were not influenced by the changes in salt intake. These results indicate that the severe restriction of dietary salt raises plasma cholesterol and uric acid levels in patients with essential hypertension in the short term.     

The short- and long-term effects of a low-fat, cholesterol-free, hypocaloric diet on serum triglyceride and cholesterol distribution in severely obese humans

The effect of weight loss on serum triglycerides (TG), and total, HDL, and LDL cholesterol was measured retrospectively over a 9-month period in 14 obese patients who lost at least 90 lbs on a very-low-calorie, nearly fat-free, formula diet of 300-450 cal/day. These measurements were repeated in seven of these patients during the first 3 months of stable weight maintenance. Changes in total, LDL and HDL cholesterol were biphasic during the hypocaloric diet, showing a decrease during the first 3 months, and subsequently approaching or reaching baseline values. No further change occurred in total cholesterol, LDL cholesterol, or HDL cholesterol during the subsequent weight maintenance phase. Triglycerides decreased by the first month of this diet and remained low throughout the entire 9-month period of caloric restriction and during a 3-month period of weight maintenance. Percentage changes in TG and HDL-C during the first 3 months of hypocaloric diet were inversely correlated with their baseline values, those with the highest initial values showing the greatest decrease, and those with the lowest values showing an increase. These results demonstrate the importance of obtaining multiple specimens over time in interpreting the effect of hypocaloric diets on serum lipids.