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 concen tration of lipid-soluble antioxidants and their distribution in very-low-de nsity, low-density and high-density lipoproteins (VLDL, LDL and HDL) was in vestigated in a cohort of control normocholesterolemic adult subjects recei ving 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 al pha-tocopherol increased from 19.44 +/- 4.77 to 38.03 +/- 9.06 mu M and thi s was associated with slight decrease in the concentration of gamma-tocophe rol from 1.27 +/- 0.97 to 0.99 +/- 1.17 mu M, without any significant chang es of either lycopene and beta-carotene. Qualitatively similar changes were found in VLDL, LDL and HDL but the net increase of alpha-tocopherol in pla sma did not correlate with the increase in alpha-tocopherol content in any of the lipoprotein types. Following supplementation, the percentage of tota l plasma alpha-tocopherol pool carried by VLDL increased from 20.97 +/- 6.0 7% 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 i n either VLDL and LDL did not exhibit any statistically relevant correlatio n with the chemical composition of these lipoproteins in the different subj ects investigated. On the other hand, the amount of alpha-tocopherol enrich ing the HDL particles was inversely related to the relative abundance of pr otein (r = 0.449; P < 0.05) and directly to the phospholipid/protein ratio (r = 0.480, P < 0.05). (C) 2000 Academic Press.