Dietary Iron Bioavailability: Agreement between Estimation Methods and Association with Serum Ferritin Concentrations in Women of Childbearing Age

Abstract

Predictive iron bioavailability (FeBio) methods aimed at evaluating the association between diet and body iron have been proposed, but few studies explored their validity and practical usefulness in epidemiological studies. In this cross-sectional study involving 127 women (18–42 years) with presumably steady-state body iron balance, correlations were checked among various FeBio estimates (probabilistic approach and meal-based and diet-based algorithms) and serum ferritin (SF) concentrations. Iron deficiency was defined as SF < 15 µg/L. Pearson correlation, Friedman test, and linear regression were employed. Iron intake and prevalence of iron deficiency were 10.9 mg/day and 12.6%. Algorithm estimates were strongly correlated (0.69≤ r ≥0.85; p < 0.001), although diet-based models (8.5–8.9%) diverged from meal-based models (11.6–12.8%; p < 0.001). Still, all algorithms underestimated the probabilistic approach (17.2%). No significant association was found between SF and FeBio from Monsen (1978), Reddy (2000), and Armah (2013) algorithms. Nevertheless, there was a 30–37% difference in SF concentrations between women stratified at extreme tertiles of FeBio from Hallberg and Hulthén (2000) and Collings’ (2013) models. The results demonstrate discordance of FeBio from probabilistic approach and algorithm methods while suggesting two models with best performances to rank individuals according to their bioavailable iron intakes.

Prevalence of iron deficiency anemia in Brazilian women of childbearing age: a systematic review with meta-analysis

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Dietary iron intake over two post-fortification periods in Brazil: data from the National Dietary Surveys 2008–2009 and 2017–2018

“…Although we could not guarantee the feasibility of assuming the recommended values, it is worth mentioning that, even in the USA, the IOM’s dietary bioavailability factor has been criticised (50) . However, a small study including Brazilian women with a similar Fe intake pattern from the general population suggested that assuming North American dietary reference values, based on the estimated bioavailability of a Western-style diet (18 %), might be acceptable in our setting (51) . Moreover, against a possible variation in dietary Fe bioavailability over the studied period, which could not be ignored, we observed that red meat, the major dietary source of haem Fe (4) , showed quite similar contributions to the total Fe intake of the population in 2008–2009 (about 13 %) and 2017–2018 (about 14 %).…”

Toddlers may be getting enough iron in long day‐care services after all

“…This algorithm was based on post‐prandial serum ferritin, not isotopic absorption, which has shown to alter the usual ratios of enhancers and inhibitors 41,59 . The second algorithm has shown the highest predictive value (98.7%) for iron status compared to other iron algorithms that have been developed 45 . In addition, it adjusts the bioavailability to iron status and is the only algorithm to our knowledge that considers the interaction between inhibitors and enhancers.…”