Sensitivity and specificity of a new, rapid and simple microprocedure for detection of serum chylomicrons

Effects of monounsaturated fatty acids v complex carbohydrates on serum lipoproteins and apoproteins in healthy men and women

The effects of a high-carbohydrate, high-fiber diet and an olive-oil-rich diet on the distribution of cholesterol over the various lipoproteins, on serum apolipoproteins, and on the composition of HDL2 and HDL3 were studied under strict dietary control. Forty-eight healthy subjects first consumed a high-saturated-fat diet [proportion of energy, en%] (saturated fat 20 en%, total fat 38 en%) for 17 days. For the next 36 days, 24 subjects consumed a diet high in complex carbohydrates (monounsaturated fat 9 en%, total fat 22 en%) and the other 24 consumed a high-fat, olive-oil-rich diet (monounsaturated fat 24 en%, total fat 41 en%). The amounts of protein (12% to 14 en%), polyunsaturated fat (4 to 5 en%), and cholesterol (31 to 35 mg/MJ) were similar in all three diets. Serum cholesterol levels fell by 0.44 mmol/L in subjects consuming the carbohydrate diet and by 0.52 mmol/L for those receiving the olive-oil-rich diet. VLDL-cholesterol levels rose by 0.08 mmol/L in the carbohydrate group and fell by 0.08 mmol/L in the olive oil group (P less than .05 for difference between test diets). HDL2 and LDL cholesterol levels fell to the same extent on both diets. HDL3 cholesterol fell by 0.09 mmol/L on the high-carbohydrate diet and increased by 0.01 mmol/L on the olive oil diet (P less than .05). There was no change in the composition of HDL3, suggesting that the fall was due to a decrease in the total number of circulating particles.(ABSTRACT TRUNCATED AT 250 WORDS)

Measures of fat distribution as determinants of serum lipids in healthy volunteers consuming a uniform standardized diet

The relation was investigated between body fat topology and serum lipoproteins in healthy, nonobese men and women. Twenty-four men and 24 women consumed a standardized affluent diet for 17 days. Serum was obtained after 14 and 17 days. Regression coefficients of lipids and lipoproteins with age, body mass index, measures of fat distribution, and estimates of fat areas at a cross-section of the body at the level of the umbilicus, were calculated. Waist-to-thigh circumference ratio proved to be the strongest correlate of serum lipids compared with other measures of fat distribution. Upon multiple regression analysis, the waist-to-thigh ratio proved to be a stronger predictor of total cholesterol, LDL-cholesterol and triglyceride levels in men than either age or body mass index. In women this was only true for HDL3-cholesterol. In addition, no significant relations were observed any more of age and body mass index with these serum lipids, with the exception of age for IDL-cholesterol in men. Estimates of intra-abdominal fat area showed in general a stronger correlation with serum lipids than estimates of subcutaneous fat area. It is concluded that, in non-obese subjects, fat distribution is a stronger determinant of serum lipids than either body mass index or age.

Serum lipids, apoproteins and nutrient intake in rural Cretan boys consuming high-olive-oil diets

A high intake of olive oil has produced high levels of high-density and low levels of low-density lipoprotein cholesterol in short-term dietary trials. To investigate long-term effects of olive oil we have studied the diet and serum lipids of boys in Crete, where a high olive oil consumption is the norm. Seventy-six healthy rural Cretan boys aged 7-9 years were studied. The diet was assessed by a 2-day dietary recall. Blood was collected according to a standardized protocol and sera were analyzed in a rigidly standardized laboratory. The mean daily intake of energy was 11.0 MJ (2629 kcal). The intake of fat (45.0% of energy) and oleic acid (27.2% of energy) was high, and that of saturated fat low (10.0% of energy), reflecting a high consumption of olive oil. The high consumption of olive oil was confirmed by a high proportion of oleic-acid (27.1%) in serum cholesteryl fatty acids. Mean concentration of serum total cholesterol was 4.42 mmol l-1 (171 mg dl-1), of HDL-cholesterol 1.40 mmol l-1 (54 mg dl-1), of serum triglycerides 0.59 mmol l-1 (52 mg dl-1), of apo-AI 1210 mg l-1 and of LDL apo-B 798 mg l-1. The body mass index of the Cretan boys (18.2 kg m-2) was on average 2 kg m-2 higher than that of boys from other countries. Contrary to our expectation, the Cretan boys did not show a more favourable serum lipoprotein pattern than boys from more westernized countries studied previously using the same protocol. Our hypothesis that a typical, olive-oil-rich Cretan diet causes a relatively high HDL- to total cholesterol ratio is not supported by the present findings.

Effect of monounsaturated fatty acids versus complex carbohydrates on high-density lipoproteins in healthy men and women

The effects of two strictly controlled diets, one rich in complex carbohydrates, the other rich in olive oil, on serum lipids were studied in healthy men and women. Serum cholesterol levels fell on average by 0.44 mmol/l in the carbohydrate group and 0.46 mmol/l in the olive oil group. HDL cholesterol levels fell by 0.19 mmol/l in the carbohydrate group and rose by 0.03 mmol/l in the olive oil group. Serum triglycerides rose by 0.19 mmol/l in the carbohydrate group and fell by 0.06 mmol/l in the olive oil group. The changes in both HDL and triglycerides were larger in men than in women. These results clearly show that the olive-oil-rich diet, unlike the complex-carbohydrate-rich diet, caused a specific fall in non-HDL cholesterol while leaving serum triglyceride levels virtually unchanged.

A new chemical procedure for selective sequential separation of serum lipoproteins

A new chemical procedure for selective sequential separation of serum lipoproteins is described. Low density lipoproteins (LDL) were precipitated by polyvinylsulfate and the precipitates were redissolved in NaCl 0.45 mol/l. Very low density lipoproteins (VLDL) were precipitated from LDL-free supernatants by PEG-6000 at 100 g/l final concentration, pH 10, and the precipitates were redissolved in NaCl 0.15 mol/l. For the precipitation of high density lipoproteins (HDL), apolipoprotein B-free supernatants were treated by PEG-6000 at 266 g/l final concentration and the precipitates were redissolved in NaCl 0.15 mol/l. The procedure was effective up to a serum triglyceride concentration of 4.0 mmol/l as well as in serum samples without chylomicrons or remnants. The determination of cholesterol and triglyceride contents in separated lipoproteins allows the study of their chemical composition in normo- and moderately hypertriglyceridemic serum samples.