Current concepts in iron deficiency anemia

Dietary Heme-Containing Proteins: Structures, Applications, and Challenges

Heme-containing proteins, commonly abundant in red meat and blood, are considered promising dietary sources for iron supplementation and fortification with higher bioavailability and less side effects. As the precise structures and accurate bioactivity mechanism of various heme-containing proteins (hemoglobin, myoglobin, cytochrome, etc.) are determined, many methods have been explored for iron fortification. Based on their physicochemical and biological functions, heme-containing proteins and the hydrolyzed peptides have been also widely utilized as food ingredients and antibacterial agents in recent years. In this review, we summarized the structural characterization of hemoglobin, myoglobin, and other heme proteins in detail, and highlighted recent advances in applications of naturally occurring heme-containing proteins as dietary iron sources in the field of food science and nutrition. The regulation of absorption rate, auto-oxidation process, and dietary consumption of heme-containing proteins are then discussed. Future outlooks are also highlighted with the aim to suggest a research line to follow for further studies.

Iron status of premenopausal women in two regions of Bangladesh: prevalence of deficiency in high and low socio-economic groups

OBJECTIVE

The objective of the study was to assess iron status in women of different physiological status of two socio-economic groups in Bangladesh.

DESIGN

Cross sectional study, using 3-day food record and blood haemoglobin, serum iron, serum ferritin concentrations.

SETTING

Two regions of Bangladesh. The Dhaka city area and west region of Nandail, Mymensingh.

SUBJECTS

Women aged 16-40 y. The low socio-economic group (group L, n=101) consisted of rural women with precarious income levels. The high socio-economic group (group H, n=90) consisted of women with high income and educational levels. The groups were composed of three sub-groups (non-pregnant non-lactating=1, pregnant = 2 and lactating = 3).

RESULTS

There was no significant difference between the corresponding sub-groups of the two socio-economic groups in dietary intake of iron. In all sub-groups, the intake of iron was much higher than the RDA level and mainly based on non-haem iron. Blood haemoglobin (B-Hb) concentration (P=0.000), serum iron concentration (P=0.005) and serum ferritin (SF) concentration (P=0.000) were affected by socio-economic status. Physiological status (PS) influenced the B-Hb concentration (P=0.000). Prevalence of anaemia ranged from 63 to 70% in group L and 27 to 66% in group H, respectively. The prevalence of empty iron store (SF concentration<12 microg/l) ranged from 35 to 59% in group L and 15 to 32% in group H, respectively. The prevalence of anaemia and iron deficiency (70 and 35% for sub-group L2; 66 and 32% for sub-group H2, respectively) were similar in the pregnant subjects of the two groups.

CONCLUSIONS

Subclinical iron deficiency was common in women of low socio-economic status. The pregnant subjects in the two groups was similar as regards iron status.

SPONSORSHIP

The study was supported by the Academy of Finland, University of Helsinki and NorFa, Norway.

Iron status and iron supplementation in children with classical phenylketonuria

Iron (Fe) status and Fe supplementation were assessed in 20 children with phenylketonuria (PKU) through dietary intake and through measurements of ferritin, hematocrit, hemoglobin, mean cellular hemoglobin, mean cellular volume, serum Fe, total iron binding capacity, unbounded iron binding capacity, transferrin saturation and transferrin. Findings were compared to reference values and to data from age-matched controls. The prescribed phenylalanine-restricted diet supplied all the recommended nutrients. Dietary Fe was present in the diets, but its bioavailability is questionable as several laboratory results were not within accepted reference values. A ferrous sulphate supplement (5 mg elemental Fe/kg daily) was given for 120 days to a group of PKU children with lower Fe parameters, thus changing some of the parameters studied. Serum ferritin (p < 0.1), transferrin saturation and serum Fe (p < 0.05) increased after the treatment. The need for improved diagnosis of Fe status and determination of whether PKU children can benefit from therapeutic Fe is discussed.

Iron deficiency and immune responses

Iron deficiency is often associated with the impairment of the immune system, particularly the functioning of T-cell lymphocytes. Studies were therefore carried out in mice to investigate the involvement of iron in T-cell functions. Iron deficiency in mice was induced nutritionally by feeding diets differing in iron content for 4 weeks to produce normal, moderately low and severely low haematological indices. The proliferation of lymphocytes stimulated by Con A from these groups of mice was significantly affected by the degree of iron deficiency. Iron depletion also resulted in decreased production of interleukin 2 (IL-2) in the proliferating cells. The implications of these findings in the manifestation of iron deficiency anaemia are discussed.

Controle da anemia ferropriva em pré-escolares por meio da fortificação de alimento com concentrado de Hemoglobina Bovina (estudo preliminar)

O efeito da introdução de biscoitos fortificados com ferro hemínico no estado de nutrição de ferro de pré-escolares foi avaliado em um estudo piloto que inclui 16 crianças, com idade entre 2 e 4 anos, de uma creche pública do estado do Piauí. A fonte de ferro utilizada foi o sangue bovino seco pelo processo de leito de jorro, uma alternativa para a secagem em spray, adaptada para a secagem de sangue. À primeira tomada de amostra, detectou-se anemia (Hb < 11 g/dL) em 12 crianças (75%). O valor médio de Hb foi de 9,4 2,6 g/dL. Os biscoitos fortificados com 3% de concentrado de hemoglobina bovina foram introduzidos na dieta oferecida (5 biscoitos (4mg Fe)/d) durante 3 meses. Após esse período, houve aumento da concentração de hemoglobina em todas as crianças e ausência de anemia (Hb = 13,2 0,2 g/dL). Os resultados obtidos apontam para a utilização do sangue total seco como uma fonte de ferro hemínico possível de ser utilizada na fortificação de alimentos, principalmente dirigidos a grupos de risco de anemia por deficiência de ferro, como é o caso dos pré-escolares.

Contributions of heme and nonheme iron to human nutrition

Dietary iron is present in food both in inorganic forms as ferrous and ferric compounds, and in organic forms, the most important of these being heme iron. The purpose of this review is to evaluate the contributions of both heme and nonheme iron in establishing and maintaining a healthful iron status. The human requirement for iron, bioavailability of heme and nonheme iron, and amounts of heme and nonheme iron in the diet are individually estimated after reviewing the relevant literature in Sections II, III, and IV, respectively. In Section V, the contribution of heme and nonheme iron to human nutrition, as compared to the human requirement for iron (Section II), is estimated after attenuating the amounts of heme and nonheme iron found in the diet (Section IV) by their bioavailabilities (Section III).