Humans serum lipid changes

The antiatherosclerotic effect of proanthocyanidin-rich grape seed extracts was examined in cholesterol-fed rabbits. The proanthocyanidin-rich extracts [0.1% and 1% in diets (w/w)] did not change the serum lipid profile, but reduced the level of the cholesteryl ester hydroperoxides (ChE-OOH) induced by 2,2/-azo-bis(2-amidinopropane-dihydrochloride (AAPH), the aortic malonaldehyde (MDA) content and severe atherosclerosis. The immuno-histochemical analysis revealed a decrease in the number of the oxidized LDL-positive macrophage-derived foam cells on the atherosclerotic lesions of the aorta in the rabbits fed the proanthocyanidin-rich extract. When the proanthocyanidin-rich extract was administered orally to the rats, proantho-cyanidin was detected in the plasma. In an in vitro experiment using human plasma, the addition of the proanthocyanidin-rich extract to the plasma inhibited the oxidation of cholesteryl linoleate in the LDL, but not in the LDL isolated after the plasma and the extract were incubated in advance. From these results, proanthocyanidins of the major polyphenols in red wine might trap ROSs in the plasma and interstitial fluid of the arterial wall, and consequently display antiatherosclerotic activity by inhibiting the oxidation of the LDL [92]. 

In conclusion, serum, liver and brain lipid concentrations, body weight change and fecal fat excretions were greater in rats fed a diet with 25% fat than in rats fed a lower fat diet. Within each level of fat, total liver lipids decreased and liver cholesterol concentration increased as level of dietary manganese increased. However, in 14 adult, human subjects fed two levels of dietary fat, dietary manganese had no effect on serum lipid parameters or fecal fat excretion. 

Serum Lipid Levels. Several reports described changes in the serum lipid profile of humans exposed to zinc suifate or gluconate for 3-12 months however, the results are mixed. Ingestion of 2.3-4.3 mg zinc/kg/day for 5-6 weeks (Chandra 1984 Hooper et al. 1980) or 0.71 mg zinc/kg/day for 12 weeks (Black et al. 1988) reduced levels of high-density lipoprotein (HDL) cholesterol. In the study by Chandra (1984), a slight increase in low-density lipoprotein (LDL) cholesterol was observed in... 

Serum lipid profiles have been measured in a number of human studies on CLA, but the results are inconsistent. This is partly due to the fact that most studies were designed to observe changes in body composition. Changes in lipid profile may be related to factors other than CLA intake, such as diet and exercise. Such factors are difficult to control in free-living subjects and are more easily studied in animal models. One study by Noone et al. (81) was designed specifically to address the effect ... 

The mechanism of thiazolidinediones (TZDs) drugs by which the change in serum lipid profile occurs is not clear, hut may involve increases in serum lipoprotein lipase and increased lipid uptake hy adipocytes and skeletal muscle (Burant and Park). It is also possible that it results from direct effects of the drug acting on PPARa (Smith, 2001). It is not clear, especially in humans, if PPARy promotes lipid clearance in the liver in a manner similar to PPARa. 

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