RESUMO
Nonheme-iron absorption from a typical Southeast Asian meal was studied to examine the effect of a common vegetable, Yod Kratin, which contains a considerable amount of iron-binding phenolic groups. Yod Kratin (leaves of the lead tree) is a very popular vegetable in Thailand. It is consumed at least once a week year round, sometimes every day, together with the main meal. With a common portion size of the vegetable (20 g), iron absorption was reduced by almost 90%. As little as 5 g inhibited iron absorption by 75%. Addition of ascorbic acid partly counteracted inhibition. Adding 100 mg ascorbic acid reduced inhibition of iron absorption from 5 g Yod Kratin by half and the inhibition from 10 g Yod Kratin by a quarter. The study illustrates the marked effect of iron-binding phenolic compounds on iron nutrition and, thus, the importance of acquiring knowledge of the content of such compounds in different foods.
Assuntos
Alimentos , Ferro/farmacocinética , Fenóis/farmacologia , Absorção , Adulto , Ácido Ascórbico/farmacologia , Relação Dose-Resposta a Droga , Humanos , Masculino , Taninos/farmacologia , Tailândia , VerdurasRESUMO
Several studies suggest that iron absorption is low from rice-based meals. Comparisons of the effect of rice starch and wheat starch on iron absorption showed that rice had no effect on absorption. Observed differences in effects on iron absorption between different batches of rice starch could be explained by differences in the phytate content. Phytate is always present in rice grains. The content varies markedly depending on the method of milling. In polished rice, the content of phytate-P varied between 11.5 and 66 mg/100 g rice (data from 45 rice mills in Thailand). The bioavailability of iron in a meal composed of meat, a vegetable and rice varied about threefold (22.1-7.5 per cent) depending on the different phytate content of the rice (4 levels between 30 and 175 mg phytate-P were studied). The inhibitory effect of the phytate in rice was overcome by adding different amounts of an ascorbic acid-rich vegetable (green collard) to the meals.
Assuntos
Absorção Intestinal , Ferro/farmacocinética , Oryza , Amido/farmacocinética , Disponibilidade Biológica , Humanos , Ácido FíticoAssuntos
Ácido Ascórbico/farmacologia , Ferro/urina , Talassemia/urina , Pré-Escolar , Ferritinas/sangue , Humanos , Masculino , Talassemia/sangueRESUMO
Iron absorption was measured from 12 Asian meals using the extrinsic tag method. Up to 50% of the nonheme iron in the meals did not exchange with the added inorganic radioiron tracer. The extent of isotopic exchange, the native iron and the "contamination" iron was measured using a recently developed in vitro method. The results imply that in measurements of iron absorption from meals, especially in developing countries, it is essential to consider the presence of contamination iron and its limited bioavailability.
Assuntos
Contaminação de Alimentos , Ferro/sangue , Absorção , Adulto , Ásia , Disponibilidade Biológica , Países em Desenvolvimento , Comportamento Alimentar , Feminino , Humanos , MasculinoRESUMO
Intestinal 59Fe absorption was measured in 16 patients with beta-thalassaemia/haemoglobin E disease and in 5 normal controls, using a total-body counting technique. The average iron absorption in the patients was 62% in contrast to 16.5% in the normal controls. 6 of the 9 splenectomized patients had absorption values above 65%, while only 2 of the 7 nonsplenectomized patients had comparably high values.