Dose-response impact of various tocotrienols on serum lipid parameters in 5-week-old female chickens

The cholesterol-suppressive action of the tocotrienol-rich-fraction (TRF) of palm oil may be due to the effect of its constituent tocotrienols on β-hydroxy-β-methylglutaryl coenzyme A (HMG-CoA) reductase activity. The tocotrienols modulate HMG-CoA reductase activity via a post-transcriptional mechanism. As a consequence small doses (5-200 ppm) of TRF-supplemented diets fed to experimental animals lower serum cholesterol levels. These findings led us to evaluate the safety and efficacy of large supplements of TRF and its constituents. Diets supplemented with 50, 100, 250, 500, 1,000, or 2,000 ppm of TRF, α-tocopherol, α-tocotrienol, γ-tocotrienol, or δ-tocotrienol were fed to chickens for 4 wk. There were no differences between groups or within groups in weight gain, or in feed consumption at the termination of the feeding period. Supplemental TRF produced a dose-response (50-2,000 ppm) lowering of serum total and LDL cholesterol levels of 22% and 52% (P