Use of a new vitamin C-deficient diet in a depletion/repletion clinical trial

• Published in: The American journal of clinical nutrition Vol. 65; no. 5; pp. 1434 - 1440
• Main Authors: King, J, Wang, Y, Welch, RW, Dhariwal, KR, Conry-Cantilena, C, Levine, M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.05.1997; American Society for Clinical Nutrition; American Society for Clinical Nutrition, Inc
• Subjects: Ascorbic Acid - administration & dosage; Ascorbic Acid - blood; Ascorbic Acid - pharmacokinetics; Ascorbic Acid Deficiency; Biological and medical sciences; Diet; Dietary Fats - administration & dosage; Dietary Proteins - administration & dosage; Energy Intake; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Humans; Iron - administration & dosage; Lipids - blood; Male; Minerals - administration & dosage; Nutrition Policy; Nutritional Physiological Phenomena; Studies; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitamin C; Vitamins - administration & dosage; Human; Ascorbic acid; Deficient diet; Vitamin; Oral administration; Bioavailability; Feeding; Increasing dose; Dietary allowance; Computer program; Food intake; Database; Clinical trial; Pharmacokinetics
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/65.5.1434

To conduct an inpatient study on the recommended dietary allowance (RDA) for vitamin C, we developed a unique vitamin C-deficient diet using a nutrient database and selective menus. Fourteen different menus were developed offering > 300 items with 0-2.4 mg vitamin C per serving. During the 4-6 mo volunteers were hospitalized, daily dietary vitamin C was restricted to < or = 5.0 mg. The mean daily dietary vitamin C intake was < 3.9 mg for the seven study subjects. With concurrent supplementation, the diet provided > or = 85% of the RDA for 17 essential nutrients. Within 3 wk of admission the diet induced vitamin C deficiency as indicated by plasma concentrations, which decreased from 23 +/- 6.9 to 6.9 +/- 2.0 mumol/L. Daily intake of vitamin C and five other nutrients was determined by nutrient database analyses. Mean energy, protein, the iron were 105-185% of the RDA and total and saturated fat were 32% and 10% of energy, respectively. Weight and nutritionally relevant indexes remained normal. Dietary adherence, calculated by the number of days with < or = 5.0 mg vitamin C per total study days, was 88-98% per repletion dose. Computer analyses of menu selections permitted individual preferences to be met while restricting vitamin C intake to < or = 5.0 mg/d. There were no complications from the diet during the depletion and repletion phase. With this diet, ascorbic acid pharmacokinetics for escalating doses could be determined in healthy volunteers.