title: Use of a new vitamin C-deficient diet in a depletion/repletion clinical trial.
abstract: 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.
authors.affiliation: Department of Nutrition, National Institutes of Health, Bethesda, MD 20892-1372, USA.
authors.forename: J
authors.initials: J
authors.lastname: King
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: R W
authors.initials: RW
authors.lastname: Welch
authors.forename: K R
authors.initials: KR
authors.lastname: Dhariwal
authors.forename: C
authors.initials: C
authors.lastname: Conry-Cantilena
authors.forename: M
authors.initials: M
authors.lastname: Levine
mesh_terms: D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D001206:Ascorbic Acid Deficiency; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D006801:Humans; D007501:Iron / Q000008:administration & dosage; D008055:Lipids / Q000097:blood; D008297:Male; D008903:Minerals / Q000008:administration & dosage; D018673:Nutrition Policy; D009747:Nutritional Physiological Phenomena; D014815:Vitamins / Q000008:administration & dosage
chemical_list: D004041:Dietary Fats; D004044:Dietary Proteins; D008055:Lipids; D008903:Minerals; D014815:Vitamins; D007501:Iron; D001205:Ascorbic Acid