Effects of modified fat diets on LDL/HDL ratio

Nutrigenomics: exploiting systems biology in the nutrition and health arena

Nutritional sciences are discovering the application of the so-called "omics" sciences. Propelled by the recent unravelling of the human genome and the coinciding technological developments, genotyping, transcriptomics, proteomics and metabolomics are now available to nutritional research. In the future we are likely to see new screening tools for the selection of bioactive nutrients, new biomarkers for the in vivo efficacy of nutrients, and better insight into the influence of genetic polymorphisms on nutrient metabolism. However, are these promises just based on biotechnological hype or is a real fundamental change in human nutritional sciences at hand?

The effect of daily consumption of coconut fat and soya-bean fat on plasma lipids and lipoproteins of young normolipidaemic men

The present paper reports the influence on plasma lipids of isoenergetic diets containing 30% of energy as fat, with a polyunsaturated: saturated fat ratio of 4.00 or 0.25, consumed for 8 weeks by twenty-five young normolipidaemic males. Approximately 70% of the fat energy was provided by the test fats: soya-bean fat and coconut fat. During the soya-bean-fat-eating period the total plasma cholesterol level fell significantly compared with baseline values (P less than 0.001) and during the coconut-fat-eating phase total plasma cholesterol level increased significantly compared with the soya-bean-eating period (P less than 0.001). On the soya-bean-fat diet, high-density-lipoprotein (HDL)-cholesterol decreased by 15% (range 6-35%) and plasma triacylglycerols decreased by 25% (range 13-37%). Results of the present study show that even when the proportion of total fat in the diet is low, a high intake of linoleic acid lowers both total plasma cholesterol and HDL-cholesterol, while a high intake of saturated fat elevates both these lipid fractions. Application of regression formulas to the present findings indicates that short-chain saturated fatty acids have a neutral effect on serum cholesterol.

The ratio of plasma high-density lipoprotein cholesterol to total and low-density lipoprotein cholesterol: age-related changes and race and sex differences in selected North American populations. The Lipid Research Clinics Program Prevalence Study

The distribution of the ratios of plasma high-density lipoprotein cholesterol (HDL-C) to total cholesterol (TC) and of HDL-C to low-density lipoprotein cholesterol (LDL-C) are presented for 6900 white and 495 black examinees greater than 4 years old. Measurements were obtained during the visit 2 survey of the Lipid Research Clinics (LRC) Program Prevalence Study, and correspond to a 15% random sample of 60,502 participants screened during the LRC visit 1 survey. Age-specific means, medians, and selected percentiles are given by sex and by gonadal hormone use in white women. Apparent in these cross-sectional data was a consistent age-related decline in the ratio of HDL-C to TC for white male participants, from a mean of 0.360 in the age group 5 to 9 to a mean of 0.211 in the age group 50 to 54. Thereafter the mean ratio increased slightly. In white women not using gonadal hormones the age-related decline in the ratio was only evident starting at the age group 35 to 39, from which it declines from 0.329 to 0.258 in the age group 55 to 59. White women using gonadal hormones showed very minor age-related changes in the HDL-C/TC ratio, varying around a mean of 0.300. The number of blacks examined was low and thus the racial comparisons must be interpreted with caution. For each gender, age-related trends were similar in black and white study participants. Black men, however, had a higher percentage of TC carried as HDL-C than white men in all age groups examined. Black women had a higher percentage of TC in HDL-C than white women only below age 20; in the adult age range no appreciable differences were seen. Pearson correlation coefficients between the lipid, lipoprotein, and lipoprotein ratios are presented. The ratio HDL-C/TC correlated highly with the ratio HDL-C/LDL-C (greater than 0.92 for all groups) and the former may be a more conveniently determined surrogate for the latter. Although not exhaustive regarding the information it conveys about a lipid pattern, the ratio HDL-C/TC has the advantage of summarizing complex associations into a single numerical approximation.

High density lipoproteins unaffected by dietary fat modification

Since diets containing a high P/S ratio have been reported to have detrimental effects on HDL, the effect of a moderately modified fat diet (P/S ratio 1.0, cholesterol content 250 mg/day) was investigated in 30 healthy male volunteers, divided into 2 groups. They were either given a modified fat diet or an isocaloric control diet (P/S ratio 0.3, cholesterol content 370 mg/day) for 3 months each in a cross-over design. After 3 months of the polyunsaturated fat diet LDL cholesterol was significantly lowered by 19 and 13%, respectively, in both groups. This effect was already apparent after 4 weeks. Apo A-I and cholesterol in serum and the subfractions HDL2 and HDL3 remained unchanged. Consequently, the ratio LDL/HDL cholesterol was decreased by this diet. Dietary adherence was good according to the typical changes of the linoleic acid content in serum cholesteryl esters, to the dietary recalls and to the constant body weight. We conclude that a moderately modified fat diet supplied from mixed general food is acceptable for longer periods, effectively lowers LDL cholesterol, even in normolipoproteinemic subjects, and has no detrimental effects on HDL.