Vitamin C concentrations in plasma as a function of intake : a meta-analysis

• Published in: International journal for vitamin and nutrition research Vol. 70; no. 5; pp. 226 - 237
• Main Authors: BRUBACHER, Dorothee, MOSER, Ulrich, JORDAN, Paul
• Format: Journal Article
• Language: English
• Published: Bern Hogrefe & Huber 01-09-2000; Kirkland, WA; Toronto, ON
• Subjects: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Ascorbic Acid - administration & dosage; Ascorbic Acid - blood; Ascorbic Acid - physiology; Bayes Theorem; Biological and medical sciences; Diet; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Humans; MEDLINE; Middle Aged; Models, Biological; Models, Statistical; Nutritional Requirements; Nutritional Status; Smoking; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Human; Feeding behavior; Ascorbic acid; Food intake; Vitamin; Concentration; Bibliographic review; Feeding; Metaanalysis; Blood plasma
• ISSN: 0300-9831; 1664-2821
• DOI: 10.1024/0300-9831.70.5.226

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.