Oral vitamin C and endothelial function in smokers: short-term improvement, but no sustained beneficial effect

AbstractOBJECTIVESTo test the hypothesis that antioxidant therapy would improve endothelial function in smokers.BACKGROUNDSeveral studies have documented a beneficial effect of short-term oral or parenteral vitamin C on endothelial physiology in subjects with early arterial dysfunction. Possible long-term effects of vitamin C on endothelial function, however, are not known.METHODSWe studied the effects of short- and long-term oral vitamin C therapy on endothelial function in 20 healthy young adult smokers (age 36 ± 6 years, 8 male subjects, 21 ± 10 pack-years). Each subject was studied at baseline, 2 h after a single dose of 2 g vitamin C and 8 weeks after taking 1 g vitamin C daily, and after placebo, in a randomized double-blind crossover study. Blood samples were analyzed for plasma ascorbate levels and endothelial function was measured as flow-mediated dilation of the brachial artery, using high resolution ultrasound. Nitroglycerin-mediated dilation (endothelium-independent) was also measured at each visit.RESULTSAt baseline, plasma ascorbate level was low in the smokers (42 ± 21 μmol/liter; normal range, 50 to 150 μmol/liter), increased with vitamin C therapy after 2 h to 120 ± 54 μmol/liter (p < 0.001) and remained elevated after eight weeks of supplementation at 92 ± 32 μmol/liter (p < 0.001, compared with placebo). Flow-mediated dilation, however, increased at 2 h (from 2.8 ± 2.0% to 6.3 ± 2.8%, p < 0.001), but there was no sustained beneficial effect after eight weeks (3.9 ± 3.2%, p = 0.26). Nitroglycerin-mediated dilation was unchanged throughout.CONCLUSIONOral vitamin C therapy improves endothelial dysfunction in the short term in healthy young smokers, but it has no beneficial long-term effect, despite sustained elevation of plasma ascorbate levels

Oestradiol improves arterial endothelial function in healthy men receiving testosterone

Summary OBJECTIVE To assess prospectively the effects of low dose oestradiol on arterial endothelial and smooth muscle function in healthy men. Oestrogen use is associated with reduced cardiovascular disease in oestrogen-deficient women, however, the vascular effects of low-dose oestradiol in healthy men have not been investigated previously. PATIENTS and DESIGN Twenty-three men (aged 32^8 years) were randomized to receive depot implants of testosteron