Vitamin C intake and plasma ascorbic acid concentration in adolescents

Abstract

The relationship between vitamin C intake and status was investigated in a group of adolescents (13-14 years old). Dietary intakes were assessed using a 7 d weighed dietary record method, coupled with the collection of duplicate diets. Vitamin C intakes calculated using food composition tables were compared with values obtained by direct analysis of duplicate diets. Vitamin C status was judged via measurement of plasma ascorbic acid (AA) concentration in blood samples taken after a 12-15 h fast. The relationship between calculated and analysed vitamin C intake and plasma AA concentration was examined. Average daily calculated vitamin C intakes, for the group (n 54) as a whole over a 7 d period, gave a good estimate of intake, as judged by prompt analysis of duplicate diets. However, analysed u. calculated intakes were significantly different for approximately one-third of subjects when data were examined on an individual basis. Large discrepancies between analysed and calculated values could not be accounted for on a food group basis. In all but two individuals, calculated vitamin C intake was in excess of the new reference nutrient intake (RNI, part of the new daily reference values (Department of Health and Social Security, 1991)) of 40 mg and all plasma AA concentrations were well above those used to indicate even a moderate risk of deficiency. A relationship between vitamin C intake and plasma AA was observed for both males (n 19) and females (n 35). However, the relationship was much stronger for males who showed a wider range of both intake and plasma AA values.

Micronutrient intake and psychological performance of schoolchildren: consideration of the value of calculated nutrient intakes for the assessment of micronutrient status in children

“…However, when data were compared on an individual daily basis, calculated vitamin C intakes ranged between at https://www.cambridge.org/core/terms. https://doi.org/10.1079/PNS19920045 0.6 and 9-5 times the value obtained by direct analysis and there was a statistical difference (using a paired t test) between analysed and calculated intakes for approximately one-third of the subjects when they were examined individually over the 7 d of dietary assessment (Finglas et al 1992). This highlights the potential unreliability of calculated data used on an individual basis.…”

“…Full details of the subjects who took part in the study, methods of dietary assessment and blood sampling are presented elsewhere (Finglas et al 1992). The study was approved by the Institute's Ethics Committee.…”

“…In most individuals the concentration of serum ferritin parallels the total amount of storage Fe and serum fenitin values of <lo bg/l for children up to 14 years are almost always indicative of a depletion of Fe stores. (100) 58 (53) ETK-Ac, EGR-Ac, erythrocyte transketolase (EC 2.2.1.1) and glutathione reductase (EC 1.6.4.2) activity coefficients (Ac) respectively, where Ac = enzyme activity with added coenzyme enzyme activity without added coenzyme * For details, see Finglas et al (1992). t See Gibson (1990).…”

Micronutrient undernutrition in British schoolchildren

“…None of the adolescents in the Nonvich study could be classified as having a low vitamin C status, whilst 5-10% of the adults fell into the 'deficient' category. These higher PAA values in our 13-14-year-olds were associated with vitamin (2 intakes well in excess of the RNI; the major source being vitamin C-rich beverages (Finglas et al 1993). Where diets do not include high intakes of these relatively expensive beverages, and where there is a lower consumption of fruit and vegetables, vitamin C and folate status might be expected to be poorer.…”

“…Further details of this study are presented elsewhere (Finglas et al 1993;Southon et al 1992). In general, the parents of the children recruited to this study could be assigned to social classes 1-111 on the basis of occupation.…”