Avaliação da capacidade de absorção de ferro em adultos com anemia falciforme e de bases para recomendações dietéticas a pessoas com sobrecarga deste micronutriente

Abstract

Iron overload diseases do not have yet a clear dietary approach or nutritional guidelines. Sickle cell anemia (SCA) is a hemoglobinopathy that can lead to secondary iron overload due to blood transfusions and is very common in Brazil, especially in regions with higher concentration of African descent. Recently, studies have observed that hepcidin – hormone responsible for iron homeostasis and the reduction of intestinal iron absorption – levels were higher in participants with iron overload compared to those without iron overload and control group. Those data suggested that individuals exposed to iron overload may not need to reduce the intake of iron-rich foods – a common recommendation prescribed by health professionals. However, these results are not sufficient to establish a nutritional recommendation, since aspects such as the iron absorption need to be further investigated. The aim of this study was to understand the basis for dietary recommendations for people with iron overload and to evaluate the iron absorption in adults with SCA. First, a scope review was carried out according to the methods proposed by the Joanna Briggs Institute and by the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) protocol in order to systematize the studies that support dietary prescriptions for patients with iron overload. An experimental and comparative study was also carried out with 25 adults, divided into groups with SCA and iron overload (n = 03), SCA without iron overload (n = 10) and individuals without the disease (n = 12). Iron absorption was measured using a labelled orange juice (100 mL) with 57Fe stable isotope. Blood samples were collected at baseline and 14 days after isotope administration and the determination of the 57Fe/56Fe isotopic ratio was determined by inductively coupled plasma mass spectrometry (ICP-MS). In the scope review, 6409 studies were recovered from databases and eight met the inclusion criteria. Although the need to restrict iron in the diet of people with hemochromatosis is quite clear, there is a consensus that IOL diminishes its absorption. The consumption of polyphenols and 6-shogaol seems to reduce iron absorption or serum ferritin concentration, while procyanidins do not cause any changes. Although vitamin C appeared to be beneficial with concomitant iron chelation therapy, the ascorbic acid supplementation should be avoided – such as excessive alcohol consumption – not only because they increase iron absorption but because they provoke toxic oxidative reactions when iron is excessive. In the second manuscript, hepcidin levels and iron absorption did not differ between all groups studied. Unlike hepcidin, serum ferritin and hepatic iron concentration were strongly and negative correlated with the percentage of iron absorbed and seems to have a greater influence in the decrease of iron absorption. Analyzing the comparison among these groups and the correlation of iron absorption capacity and these parameters, we believe that individuals with SCA (with or without iron overload) may not need to reduce their intake of iron-rich food, maintaining their absorption similar to the individuals without the disease. Further studies evaluating the intestinal iron absorption using larger sample sizes of SCAio patients should be conducted to assist in the establishment of a safe nutrition approach to be adopted.