[Determination of the blood ascorbic acid level after administration of slow-release vitamin C]

The aim of the present study was to test the effects of a slow releasing form of vitamin C in smokers, because the single high dose previously proposed for smokers gave a transient increase of plasma ascorbate, being rapidly absorbed in the gastrointestinal tract and is rapidly excreted with urine.

In a double-blind placebo-controlled study 18 subjects received both Vitamin C (C-test) and placebo (P-test) in two different periods. During the test-day the subject followed a controlled diet and food Intake was assessed by semiquantitative questionnaire. Peripheral blood sample were collected in fasting conditions, in the morning, before and after 4, 8, 12 and 24 hours from the treatment. Blood sample was collected into EDTA-containing tubes, immediately centrifuged and treated for ascorbate determination, and stored at -70 degrees C until chromatographic analysis.

Smokers and nonsmokers were similar for age, height, weight, BMI and for vegetable and fruit consumption. Ascorbic acid level was significantly (p < 0.05) lower than the references level in all subjects, however there were no differences between smokers and non smokers plasma ascorbate concentration increased significantly at T1, T2 and T3 respect to T0 during C test (p < 0.005), whenever remaining higher than T0 was not still significant in T4.

Our results demonstrate that a slow releasing form of Vitamin C could be useful in clinical pharmacology to increase and to maintain to a constant rate ascorbate level, both in smokers and non smokers with a single daily administration.