Steady-state turnover and body pool of ascorbic acid in man

Area of Science:

• Human physiology
• Pharmacokinetics
• Nutritional science

Background:

• Ascorbic acid (vitamin C) is an essential nutrient.
• Understanding ascorbic acid's metabolic fate is crucial for determining optimal intake levels.
• Previous research has explored vitamin C absorption and excretion, but detailed pharmacokinetic profiles require further investigation.

Purpose of the Study:

• To investigate the pharmacokinetic behavior of ascorbic acid following oral administration.
• To determine the relationship between ascorbic acid dosage and its half-life and body pool size.
• To estimate the daily intake required to achieve near-saturating body stores in the general population.

Main Methods:

• Healthy, non-smoking male volunteers received a single oral dose of (1-14C)ascorbic acid.
• Radioactivity levels in plasma and urine were monitored over time.
• Pharmacokinetic principles were applied to calculate turnover, pool size, metabolism, and excretion rates.

Main Results:

• The half-life of ascorbic acid was found to be inversely proportional to the administered dose.
• Increasing the dosage of ascorbic acid increased the body's total pool size, reaching up to 20 mg/kg bodyweight.
• Calculations suggest a daily intake of approximately 100 mg ascorbic acid is sufficient to saturate the body's vitamin C pool in about 95% of individuals.

Conclusions:

• Ascorbic acid pharmacokinetics are dose-dependent.
• Higher ascorbic acid intake leads to larger body stores and a longer retention time.
• A daily intake of 100 mg of ascorbic acid is recommended to maintain adequate body stores for the majority of the population.