Vitamin C depletion is associated with alterations in blood histamine and plasma free carnitine in adults

Objective: The purpose of this study was to determine whether carnitine metabolism or histamine degradation would be useful parameters for investigating the optimal requirement for vitamin C. Methods: Twenty-two non-scorbutic subjects with subnormal vitamin C status (plasma vitamin C <28 mu mol/L) were placed on a metabolic diet low in vitamin C for 3 seeks and repleted with graded doses of vitamin C: 10, 30 and 60 mg vitamin C daily (group 1) or 10, 125 and 250 mg vitamin C daily (group 2) far weeks 1, 2 and 3, respectively. Fasting blood samples were collected weekly and analyzed for plasma vitamin C, plasma free carnitine and blood histamine. Results: Group 1 subjects remained in a subnormal vitamin C state throughout the 3-week study, and blood histamine and plasma free carnitine were not impacted by the experimental treatment. Plasma vitamin C in group 2 subjects rose significantly during the study, and these subjects finished the study with an ample Vitamin C status indicative of vitamin C intakes above the recommended dietary allowance. Bath blood histamine and plasma free carnitine were inversely related to vitamin C status in group 2 subjects. Conclusions: These data indicate that blood histamine and plasma free carnitine are altered in individuals with subnormal, non-scorbutic vitamin C status and provide evidence that metabolic changes independent of collagen metabolism occur prior to the manifestation of scurvy. Thus utilizing scurvy as an end-point to determine vitamin C requirements may not provide adequate vitamin C to promote optimal health and well-being.