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Nutrients. 2020 Feb 6;12(2). pii: E418. doi: 10.3390/nu12020418.

Erythrocyte Ascorbate Is a Potential Indicator of Steady-State Plasma Ascorbate Concentrations in Healthy Non-Fasting Individuals.

Author information

1
Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago, Christchurch, PO Box 4345, 8140 Christchurch, New Zealand.
2
Mackenzie Cancer Research Group, Department of Pathology and Biomedical Science, University of Otago, Christchurch, PO Box 4345, 8140 Christchurch, New Zealand.
3
Nutrition in Medicine Research Group, Department of Pathology and Biomedical Science, University of Otago, Christchurch, PO Box 4345, 8140 Christchurch, New Zealand.

Abstract

Plasma vitamin C concentrations fluctuate in response to recent dietary intake; therefore levels are typically determined in the fasting state. Erythrocyte ascorbate concentrations have been shown to be similar to plasma levels, but little is known about the kinetics of ascorbate accumulation in these cells. In this study, we investigated ascorbate uptake into erythrocytes after dietary supplementation with vitamin C and compared it to changes in plasma ascorbate concentrations. Seven individuals with baseline fasting plasma vitamin C concentrations ≥ 50 µmol/L were depleted of vitamin C-containing foods and drinks for one week, and then supplemented with 250 mg vitamin C/day in addition to resuming their normal diet. Fasting or steady-state plasma ascorbate concentrations declined to almost half of their baseline concentration over the week of vitamin C depletion, and then returned to saturation within two days of beginning supplementation. Erythrocyte ascorbate concentrations exhibited a very similar profile to plasma levels, with values ~76% of plasma, and a strong linear correlation (r = 0.89, p < 0.0001). Using a pharmacokinetic study design in six individuals with baseline fasting plasma vitamin C concentrations ≥50 µmol/L, we also showed that, unlike plasma, which peaked between 2 and 4 h following ingestion of 200 mg of vitamin C, erythrocyte ascorbate concentrations did not change in the six hours after supplementation. The data from these two intervention studies indicate that erythrocyte ascorbate concentration provides a stable measure of steady-state plasma ascorbate status and could be used to monitor ascorbate status in healthy non-fasting individuals.

KEYWORDS:

ascorbate; dehydroascorbic acid; erythrocyte; pharmacokinetic; plasma; steady-state; vitamin C

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