Iron status, inflammation and anthropometric nutritional status of four–to–thirteen month old black infants from a rural South African population
Background - The first 1000 days of life (from conception to two years of age) is a critical period of nutritional vulnerability, affecting lifelong health. Iron deficiency (ID) and iron deficiency anaemia (IDA) are considered major public health problems that adversely affect development and growth, impair immunity, and increase morbidity and mortality in infants. ID and IDA in sub-Saharan Africa can be attributed to poor dietary, socioeconomic and disease conditions. One of the major obstacles in determining the prevalence of ID, using serum ferritin (SF) as marker of iron status, is that it not only reflects the amount of iron that is stored in the body, but also functions as an acute phase reactant that is raised in the presence of infection or inflammation. Aim - We conducted a re-analysis of the International Research on Infant Supplementation (IRIS) study’s baseline data to determine a more accurate estimation of the ID prevalence in apparently healthy four to thirteen-month-old infants from rural KwaZulu-Natal while accounting for the effect of chronic and acute inflammation on SF. Study design and methods - A cross-sectional analysis was performed on the baseline data (192 infants) of the IRIS study that was conducted in 2000. Infants’ haemoglobin (Hb), SF, C-reactive protein (CRP) and alpha-1 glycoprotein (AGP) concentrations were interpreted to determine the prevalence of ID. Literature of the past four years served as a guide to compare the ID prevalence obtained from four methods that account for the influence of inflammation on SF concentrations, to a reference method that does not take inflammation into consideration, and to what was reported in the original IRIS study. Weight and recumbent length measurements were converted to z-scores to interpret subjects’ anthropometric nutritional status. Results - A high prevalence of inflammation (52.6%) was present, with 11.5% of the subjects being in the incubation, 17.2% in the early convalescent, and 24% in the late convalescent phase of inflammation. SF was significantly associated with both CRP (ß = 0.200; P = 0.005) and AGP (ß = 0.223; P = 0.002) when adjusting for gender and age. The IRIS study reported an ID prevalence of 18.3%, whereas the results of this study ranged from 17.2 to 52.1%. We derived an IDA prevalence that ranged from 12 to 24.5% according to the different methods. The prevalence of stunting [length-for-age Z-score <-2SD] was 12.5%; while 25.1% of infants were overweight/obese [weight-for-length z-score >2SD]. Conclusion - A double burden of malnutrition was evident from the high prevalence of both overweight and ID, together with inflammation. The disconcertingly large variance in ID prevalence observed between the different methods that were employed highlights that iron supplementation interventions to treat anaemia must be based upon accurate estimates of IDA prevalence, otherwise they pose an increased risk of adverse effects to susceptible, iron-replete, but anaemic infants. Given the detrimental consequences of ID, it is imperative that governments, health care providers and parents must act to prevent or treat ID and IDA among vulnerable infants.
- Health Sciences