Distribution of lipid-soluble antioxidants in lipoproteins from healthy subjects. II. Effects of in vivo supplementation with alpha-tocopherol.

The effects of orally supplemented dl -alpha-tocopherol on the plasma concentration of lipid-soluble antioxidants and their distribution in very-low-density, low-density and high-density lipoproteins (VLDL, LDL and HDL) was investigated in a cohort of control normocholesterolemic adult subjects receiving 600 mg alpha-tocopherol daily for 2 weeks. This regimen did not modify the plasma lipid profile (total, LDL and HDL cholesterol and triglycerides) and chemical composition of VLDL, LDL and HDL. Plasma concentration of alpha-tocopherol increased from 19.44+/-4.77 to 38. 03+/-9.06 microm and this was associated with slight decrease in the concentration of gamma-tocopherol from 1.27+/-0.97 to 0.99+/-1.17 microm, without any significant changes of either lycopene and beta-carotene. Qualitatively similar changes were found in VLDL, LDL and HDL but the net increase of alpha-tocopherol in plasma did not correlate with the increase in alpha-tocopherol content in any of the lipoprotein types. Following supplementation, the percentage of total plasma alpha-tocopherol pool carried by VLDL increased from 20. 97+/-6.07% to 33.57+/-6.97%, whereas it decreased from 41.85+/-7.02% to 36.36+/-5.69% in the case of LDL and from 37.17+/-6.04% to 30.05+/-4.88% in the case of HDL. The absolute and relative enrichment of alpha-tocopherol in either VLDL and LDL did not exhibit any statistically relevant correlation with the chemical composition of these lipoproteins in the different subjects investigated. On the other hand, the amount of alpha-tocopherol enriching the HDL particles was inversely related to the relative abundance of protein (r =0.449;P<0.05) and directly to the phospholipid/protein ratio (r =0.480, P<0.05).