title: Vitamin C concentrations in plasma as a function of intake: a meta-analysis.
abstract: The purpose of this study was to estimate the intake-plasma relationship for vitamin C by means of a meta-analysis. A MEDLINE search revealed 30 publications matching our inclusion criteria. We completed the set with 5 older papers and with one monograph. The proposed statistical model corrects for inconsistencies with regard to methodological differences between the various studies. Therefore, the contribution of a particular study to the estimation is independent of the number of data points. The estimations were performed for the complete data set as well as for different subgroups: "adult" aged 15-65 years, "elderly" aged 60-96 years, "nonsmokers" and "smokers". The 50th percentile of the plasma concentration for a daily vitamin C intake of 60 mg was 42.4 mumol/L. The corresponding values for the different subgroups were: "adult" 44.1 mumol/L, "elderly" 31.0 mumol/L, "nonsmokers" 42.4 mumol/L, and "smokers" 33.6 mumol/L. Thus, this meta-analysis confirms earlier results that the requirements of vitamin C is higher in "elderly" and "smokers" compared to "adult" and "nonsmokers" and it can be used for the estimation of the vitamin C intake in order to achieve a desired plasma level within a target population. In the general population the assumed optimal plasma concentration of 50 mumol/L, as proposed by a consensus conference, can be achieved by the intake of 100 mg per day, which is the new recommendation of the Austrian, German, and Swiss Nutrition Societies.
authors.affiliation: Institute of Experimental Gerontology, Basel, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Brubacher
authors.forename: U
authors.initials: U
authors.lastname: Moser
authors.forename: P
authors.initials: P
authors.lastname: Jordan
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000097:blood* / Q000502:physiology; D001499:Bayes Theorem; D004032:Diet; D006801:Humans; D016239:MEDLINE; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D009751:Nutritional Requirements; D009752:Nutritional Status; D012907:Smoking
chemical_list: D001205:Ascorbic Acid