DO DIETARY PHYTOCHEMICALS WITH CYTOCHROME-P-450 ENZYME-INDUCING ACTIVITY INCREASE HIGH-DENSITY-LIPOPROTEIN CONCENTRATIONS IN HUMANS

Low plasma concentrations of high-density lipoprotein (HDL) are associ ated with increased risk of coronary heart disease. Several drugs that induce the microsomal cytochrome P-450-dependent enzyme system in liv er and intestine, the sites of HDL apolipoprotein (apo) A-I and A-II s ynthesis, raise plasma HDL concentrations in humans. To test the hypot hesis that phytochemicals with cytochrome P-450-inducing activity may also increase plasma HDL concentrations, two controlled dietary trials were undertaken in healthy nonsmoking males aged 20-28 y. One study e xamined the effect of replacing 300 g glucosinolate-free vegetables wi th 300 g Brussels sprouts/d for 3 wk. The other study examined the eff ects of 150 mg eugenol/d in capsule form, using a double-blind, placeb o-controlled crossover design. There were no significant increases in plasma apo A-I, apo A-II, HDL cholesterol, or HDL phospholipids. There results suggest that dietary phytochemicals that induce members of th e cytochrome P-450 system do not necessarily raise plasma HDL concentr ations in humans, but do not exclude the possibility that some phytoch emicals may have such an effect.