Oily fish increases iron bioavailability of a phytate rich meal in young iron deficient women.

BACKGROUND: Iron deficiency is a major health problem worldwide, and is associated with diets of low iron bioavailability. Non-heme iron absorption is modulated by dietary constituents, one of which is the so-called "meat factor", present in meat, fish (oily and lean) and poultry, which is an important enhancer of iron absorption in humans. Food processing also affects iron bioavailability. OBJECTIVE: To evaluate the effect of consuming sous vide cooked salmon fish on non-heme iron bioavailability from a bean meal, rich in phytate, in iron-deficient women. DESIGN: Randomized crossover trial in 21 young women with low iron stores (ferritin < 30 microg/L). Two test meals were extrinsically labelled with stable isotopes of iron (Fe-57 or Fe-58). Iron bioavailability was measured as the incorporation of stable isotopes into erythrocytes 14 d after meals consumption. RESULTS: The addition of fish to the bean meal significantly increased (p < 0.001) iron absorption. Serum ferritin concentration and iron absorption were inversely correlated for both the bean meal (R(2) = 0.294, p = 0.011) and the fish and bean meal (R(2) = 0.401, p = 0.002). CONCLUSION: Sous vide cooked salmon fish increases iron absorption from a high phytate bean meal in humans.

A lactic acid-fermented oat gruel increases non-haem iron absorption from a phytate-rich meal in healthy women of childbearing age.

Lactic acid-fermented foods have been shown to increase Fe absorption in human subjects, possibly by lowering pH, activation of phytases, and formation of soluble complexes of Fe and organic acids. We tested the effect of an oat gruel fermented with Lactobacillus plantarum 299v on non-haem Fe absorption from a low-Fe bioavailability meal compared with a pasteurised, fermented oat gruel and non-fermented oat gruels. In a cross-over trial twenty-four healthy women with a mean age of 25 (sd 4) years were served (A) fermented gruel, (B) pasteurised fermented gruel, (C) pH-adjusted non-fermented gruel, and (D) non-fermented gruel with added organic acids. The meals were extrinsically labelled with 55Fe or 59Fe and consumed on 4 consecutive days, for example, in the order ABBA or BAAB followed by CDDC or DCCD in a second period. Fe absorption was determined from isotope activities in blood samples. The fermented gruel with live L. plantarum 299v increased Fe absorption significantly (P < 0.0001) compared with the pasteurised and non-fermented gruels. The lactic acid concentration in the fermented gruel was 19 % higher than in the pasteurised gruel, but the Fe absorption was increased by 50 %. In the gruel with organic acids, the lactic acid concentration was 52 % lower than in the pasteurised gruel, with no difference in Fe absorption. The fermented gruel increased non-haem Fe absorption from a phytate-rich meal in young women, indicating a specific effect of live L. plantarum 299v and not only an effect of the organic acids.

Algorithms to assess non-heme iron bioavailability.

While sufficient information exists on the effect of individual factors on iron absorption, their net effect in a mixed meal is less well characterized, being dependent on the combination and quantity of the factors present in the meal. Over a period of more than 25 years, several models have been developed to estimate non-heme iron bioavailability, either to assess iron absorption from a meal or iron sufficiency in populations. Initially, a model was developed to calculate iron absorption in individuals with varying iron status that included only enhancers. This model was useful in classifying the diets but has limited value for accurale assessment. Later models were modified and improved by including inhibitors in the calculations. However, some included either phytate or tea but not in combination. The models that included all the factors in calculations assumed their effect was independent and additive rather than interactive, which is an important issue in addressing iron bioavailability. Although some of the models correlated estimated bioavailability with iron status of the population, the accuracy of the estimations is of concern due to lack of quantitative measurements of bioavailability modifiers, inability to consider interactive effects, and the use of non-iron status measurements. Recent research has led to the development of refined models to assess iron bioavailability of complex meals by comprehensively taking into consideration the interactive effect among enhancers and inhibitors. However, the models are based on single-meal studies and their application to whole diets at a population level is not clear. Accurate measurements of dietary factors and independent validation are needed before using these models. To date, no single model is applicable to all diets and additional studies are needed to develop new models to predict bioavailability of whole diets accurately, in addition to addressing dietary adequacy in all populations.

Absorption of non heme iron in typical and standard meals using extrinsically labeled iron 59Fe.

OBJECTIVE: To study the bioavailibility of nonheme iron from standard and test meals in Pakistani adults and to determine iron absorption using extrinsically tagged iron 59Fe. SUBJECTS AND METHODS: Nonheme iron absorption was measured from standard and test meals in ten healthy individuals. Total calories, carbohydrates, proteins, fats, ascorbic acid, total iron, phytate and ascorbic acid content were determined in both meals. Retention of iron was detected by whole body counting using gamma counter before and after administration of standard, test meals and reference dose. RESULTS: Iron absorption with test meal was 13% and after adjustment with serum ferritin and reference dose was 16.5 % and 14% respectively. The absorption of standard meal was 6.7% which after adjustment with serum ferritin and reference dose was 8.8% and 6.9% respectively. The iron and ascorbic acid content of test meal was 6.5 mg and 5.7 mg respectively while phytate phosphorus content was 114 mg. The iron and ascorbic acid content of standard meal was 1.3 mg and 2.4 mg respectively while phytate phosphorus content was 137 mg. CONCLUSION: This evaluated absorption from one of the typical Pakistani diet compared to the standard meal was better. This shows that there are some other physiological factors that lead to iron deficiency anemia in Pakistan.

Nonheme-iron absorption from a phytate-rich meal is increased by the addition of small amounts of pork meat.

BACKGROUND: Muscle tissue from various sources is known to promote nonheme-iron absorption. However, systematic studies of the dose dependency of this effect of meat on iron absorption from an inhibitory meal with low amounts of meat are lacking. OBJECTIVE: We investigated the dose-response effect of small amounts of meat on nonheme-iron absorption from a meal presumed to have low iron bioavailability. DESIGN: Forty-five healthy women with a mean (+/-SD) age of 24 +/- 3 y were randomly assigned to 1 of 3 groups, each of which was served (A) a basic meal (rice, tomato sauce, pea purée, and a wheat roll) and (B) the basic meal with either 25, 50, or 75 g pork (longissimus muscle). Meal A contained 2.3 mg nonheme iron, 7.4 mg vitamin C, and 220 mg (358 micro mol) phytate. Each meal was served twice, and the order of the meals was ABBA or BAAB. The meals were extrinsically labeled with (55)Fe or (59)Fe. Iron absorption was determined from measurements of (59)Fe whole-body retention and the activity of (55)Fe and (59)Fe in blood samples. RESULTS: Twenty-five grams meat did not increase nonheme-iron absorption significantly (P = 0.13), whereas absorption increased 44% (P < 0.001) and 57% (P < 0.001), respectively, when 50 and 75 g meat were added to the basic meal. In absolute values, this corresponds to an absorption that was 2.6% and 3.4% higher, respectively, than that with the basic meal after adjustment of the data to a level of 40% absorption from a reference dose. CONCLUSION: Small amounts of meat (>or=50 g) significantly increase nonheme-iron absorption from a phytate-rich meal low in vitamin C.