Micronutrients in childhood and the influence of subclinical inflammation

Abstract

In the present paper biomarkers of micronutrient status in childhood and some of the factors influencing them, mainly dietary intake, requirements and inflammation will be examined. On a body-weight basis the micronutrient requirements of children are mostly higher than those of an adult, but most biomarkers of status are not age-related. A major factor that is often overlooked in assessing status is the influence of subclinical inflammation on micronutrient biomarkers. In younger children particularly the immune system is still developing and there is a higher frequency of sickness than in adults. The inflammatory response rapidly influences the concentration in the blood of several important micronutrients such as vitamin A, Fe and Zn, even in the first 24 h, whereas dietary deficiencies can be envisaged as having a more gradual effect on biomarkers of nutritional status. The rapid response to infection may be for protective reasons, i.e. conservation of reserves, or by placing demands on those reserves to mount an effective immune response. However, because there is a high prevalence of disease in many developing countries, an apparently-healthy child may well be at the incubation stage or convalescing when blood is taken for nutritional assessment and the concentration of certain micronutrient biomarkers will not give a true indication of status. Most biomarkers influenced by inflammation are known, but often they are used because they are convenient or cheap and the influence of subclinical inflammation is either ignored or overlooked. The objective of the present paper is to discuss: (1) some of the important micronutrient deficiencies in childhood influenced by inflammation; (2) ways of correcting the interference from inflammation.

Deficiencia de vitamina A e fatores associados em criancas de areas urbanas

“…This means it is necessary to verify whether the vitamin A defi ciency is due to insuffi cient intake Continue or whether it is a secondary response to an infection. 20 Food intake was not assessed in this study, which can be considered a limitation.…”

“…2,c Infections can result in reduced serum retinol concentrations in the fi rst 24 hours after onset. The presence of sub-clinical infection may lead to VAD due to reductions in the retinol binding protein, 20 regardless of insuffi cient intake of food sources and the hepatic reserves of the vitamin. However, episodes of serious or prolonged infection may affect hepatic reserves, due to reduced food intake, lower absorption, increased biological use and abnormal urinary excretion of retinol serum.…”

Bioequivalence of β‐carotene and retinol

“…In vitro studies in which carotenoids are exposed to stimulated neutrophils certainly indicate that plasma carotenoids are at increased risk of destruction in such circumstances. 25,26 Furthermore, the work of Cser et al 19 and our own 20 suggests that in humans α-and β-carotene concentrations in plasma are more sensitive to oxidation than lutein concentrations and this has also been observed in in vitro studies. 27 In field studies done in free-living communities in developing countries, the volunteers recruited may be apparently healthy, but in such situations disease exposure is high and infestation by intestinal parasites is also common; thus the presence of subclinical inflammation is highly likely.…”

“…Both anaemia and low retinol concentrations are characteristic of subjects with subclinical inflammation. 4,20 A large confidence interval in the increase in serum β-carotene concentrations in the enriched-wafer group was also reported, which the authors suggested was due to a large between-individual variation in bioavailability of β-carotene. The same observation was made by Bulux et al 46 (Fig.…”

“…Likewise, in apparently healthy, HIV-1 positive patients, we also found evidence of inverse associations of all the plasma carotenoid concentrations with acute-phase protein concentrations but especially the indicator of chronic infection, α 1 -acid glycoprotein. 20 The work by Cser et al 19 is particularly interesting as they reported that the carotenoid concentration of children with infection was only 20% of that in a comparable group of healthy controls. They also suggest that the fall in carotenoid concentrations was rapid since their blood samples were taken within 24-72 h of the children falling sick.…”