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Biomedical subjects

E Björn-Rasmussen

Publications and source records attributed to E Björn-Rasmussen.

At least 37 records · Page 2Linked to original sources
PubMed1979

The measurement of food iron absorption in man. A methodological study on the measurement of dietary non-haem-Fe absorption when the subjects have a free choice of food items.

1. The present study was considered as a first step to develop a method to measure food iron absorption from realistic common meals prepared and consumed by the subjects themselves in their own homes. The absorption of Fe from the meals was measured by means of the extrinsic-tag method modified to allow for a free choice of food items. 2. The mean Fe intake was 2.79 mg and the mean Fe absorption approximately 0.30 mg. The Fe status of the subjects corresponded to 31.5% absorption from a reference dose solution containing 3 mg elemental Fe as ferrous ascorbate. The variation in food Fe absorption obtained in this field study was found to be of the same magnitude as that obtained in studies performed under more controlled conditions as in the laboratory. 3. The conclusion was drawn that the proposed method could be used in realistic field studies aimed at, for example, explaining or preventing a high prevalence of deficiency. A suffciently long run-in period and a careful instruction of the subjects was considered essential for the design of future field studies.

Adult↗
PubMed1979

Absorption of iron from breakfast meals.

The absorption of nonheme iron from nine common Western type breakfasts was studied in 129 subjects using extrinsic labeling with radioiron. In one group the iron absorption from a continental type of breakfast served with coffee was standardized against the absorption from a reference dose of derrous ascorbate (3 mg Fe). In all subsequent experiments the absorption from this breakfast was compared with one of the other breakfast meals served on alternate days and each labeled with a different radioiron isotope. The bioavailability of iron in the different breakfast meals varied markedly. There was almost a 6-fold idfference in absorption (0.07 to 0.40 mg) despite of the fact that the iron content only varied from 2.8 to 4.2 mg. The most marked effect was seen with tea which reduced the absorption to less than half and with orange juice which increased the absorption two and a half times. The present findings must be considered when giving dietary advice to groups of subjects who are known to have a critical iron balance. The present results also imply that an evaluation of the iron nutrition in a population cannot only be based on the daily dietary intake of iron but must also include the bioavailability of iron in frequently consumed meals.

Adolescent↗
PubMed1979

Effect of animal proteins on the absorption of food iron in man.

The way in which meat and fish act to promote the absorption of nonheme iron in food is not known. The present paper is a report of the results of a series of studies aimed at obtaining some insight into the mechanism of action of meat and other animal proteins on the absorption of food iron. Beef, fish, chicken and calf thymus all increased the iron absorption to about the same extent. Neither egg albumin, cysteine or a water extract of beef did, however, affect the absorption of food iron. Beef increased the absorption of a solution of inorganic iron given without food only when the iron salt was trivalent or when sodium phytate was added to the solution. It was concluded that meat acts by counteracting luminal factors that inhibit iron absorption. The most probable mechanism for this action is formation of a luminal carrier which transports the iron to the mucosal cell membrane.

Achlorhydria↗
PubMed1978

Iron absorption from South-East Asian diets and the effect of iron fortification.

The increase in iron absorption was measured when different amounts of ferrous sulphate were added to rice-based South-East Asian meals. The study comprised 158 subjects--118 women and 40 men. Iron fortification of simple meals composed of rice, boiled vegetables, and a curry to a level of 5 mg of iron per meal increased the absorption by about 0.2 to 0.3 mg of iron per meal. The additionof fish to such a meal doubled the absorption increase at a fortification level of 5 mg per meal. This absorption increase was about the same as obtained with composite western-type meals containing fish or meat. The results indicate that iron fortification programs may be effective in countries with rice-based diets provided that there is a suitable vehicle available for fortification.

Absorption↗
PubMed1978

Absorption from iron tablets given with different types of meals.

The absorption of iron from tablets given with 5 types of meals was studied in 153 subjects. The meals were: a hamburger meal with beans and potatoes, a simple breakfast meal, a Latin American meal composed of black beans, rice and maize and two Southeast Asian meals composed of rice, vegetables and spices served with and without fish. The groups were directly compared by relating the absorption from the iron tablets to the absorption from a standardized reference dose of iron given on an empty stomach. The composition of meals with respect to content of meat or fish or the presence of large amounts of phytates seemed to have no influence on the absorption of iron from tablets. The absorption from iron tablets was about 40% higher when they were given with rice meals than when they were given with the other meals studied. The average decrease in absorption by meals was about 50-60% based on a comparison when tablets were given on an empty stomach. When tablets from which the iron was released more slowly were used, the absorption increased by about 30% except when they were given with rice meals, where the absorption was unchanged. The differences among the meals in their effect on the absorption of iron from tablets thus disappeared when the slow-release tablets were given.

Administration, Oral↗
PubMed1977

Iron absorption from Southeast Asian diets. II. Role of various factors that might explain low absorption.

Previously reported levels of iron absorption from common Southeast Asian meals composed of rice, vegetables, and spices were too low to be consistent with the known prevalence of iron deficiency. In the present paper the cause of the low absorption was systematically sought. Variables investigated comprised methodological errors, factors in the diet such as certain foodstuffs, or contaminants inhibiting the absorption and characteristics of the subjects accompanied by malabsorption of dietary iron. The latter was excluded by comparing the absorption from both wheat rolls and a composit rice meal in Thai and Swedish women using the absorption of a small dose of ferrous ascorbate as a common basis of comparison. Two main factors were identified as causing the low absorption in the previous studies: the homogenization of the labeled meals before serving and the use of rice flour instead of rice. Iron absorption from nonhomogenized meals of identical composition as studied previously was many times higher (on an average 0.16 mg) and was consistent with the actual prevalence of iron deficiency in lower socioeconomic groups of Thais mainly consuming the simple meals studied. Recent modifications of the method to measure nonheme iron absorption from composite meals have thus not only made the determination simpler but also more accurate.

Adult↗
PubMed1976

Measurement of iron absorption from compositite meals.

In earlier studies using the recently introduced extrinsic tag technique meals were carefully minced and mixed with the extrinsic tracer to ensure complete isotopic exchange. In the present paper the validity of simpler and more realistic techniques to label and serve composite meals was evaluated. Equal or almost equal absorption figures were found when mixing the label homogenously into a meal, adding it dropwise, or mixing it into the most bulky component of the meal. The necessity of serving the meals in a realistic way was underlined by the finding of higher absorption from a meal in which the components were served separately than from meals mixed before serving. The results of the present study indicate that the validity of using the reference dose as a basis for comparison of absorption data in different groups, was higher when serving the reference dose and the meals on consecutive days than when serving 2 weeks apart. This was true especially in women. The present findings imply that it is both necessary and possible to design simple labeling techniques that allow valid measurements of iron absorption from composite meals. Moreover, when determining the schedule of serving the meals and the reference doses the findings in the present paper must be carefully considered.

Adult↗
PubMed1976

Absorption of iron from slow-release and rapidly-disintegrating tablets - a comparative study in normal subjects, blood donors and subjects with iron deficiency anaemia.

The absorption of iron from slow-release and rapidly-disintegrating ferrous sulphate tablets has been compared using a double radioiron isotope technique. The studies were performed in 15 normal subjects, 20 blood donors and 10 patients with iron deficiency anaemia. The preparations containing 100 mg of ferrous iron were given twice daily on alternate days for 10 days. The absorption differed significantly between the three groups of subjects, being highest in the anaemic patients and lowest in the normal subjects. In all groups, significantly more iron was absorbed from the slow-release tablets compared to the rapidly-disintegrating tablets. The mean absorption ratios were 1.3 in both normal subjects and blood donors. In patients with iron deficiency anaemia the ratio was 1.4.

Adult↗
PubMed1975

Dietary iron absorption in pregnancy - a longitudinal study with repeated measurements of non-haeme iron absorption from whole diet.

In 22 healthy women the non-haeme iron absorption (bone-marrow smears and haematological parameters) was studied at the 12th, the 24th and the 36th week of gestation and two months after delivery. In eight non-pregnant women and in seven pregnant women (at the 36th week of gestation) the absorption of food iron was measured from different types of meals. The iron absorption was measured from radioiron-labelled test meals using a whole-body counter with a very high sensitivity. During pregnancy the non-haeme iron absorption increased continuously from less than 1 % in early pregnancy to almost 15 % in late pregnancy. Calculations indicated that the amount of iron absorbed from the diet covered only about half of the demands. The increasing absorption of food iron during pregnancy seems to be related to the still more increasing demands. However, the very low absorption values in early pregnancy was quite unexpected. The amount of iron absorbed was actually below the basal demands, which means that even in early pregnancy, for reasons unknown, there is a negative iron balance. Further studies are necessary to elucidate the significance of this finding. Two months after delivery the absorption of iron from the diet was increased compared to in non-pregnant women and exceeded the demands at that phase thus indicating that a positive iron balance was achieved.

Adult↗
PubMed1974

Food iron absorption in man. Applications of the two-pool extrinsic tag method to measure heme and nonheme iron absorption from the whole diet.

A new radioisotope method to measure iron absorption from the whole diet was used in this study. The method is based on the concept that food iron is absorbed from two pools, the heme iron pool and the nonheme iron pool, which can be especially labeled with two radioiron isotopes given as hemoglobin and as an iron salt. The purpose of this study was to test the accuracy of this two-pool extrinsic tag method. The meals served were composed as an average of 6 wk consumption in the present material of 32 young enlisted men. The mean and total heme and nonheme iron absorption in all the 32 young men was 1.01+/-0.11. This figure agrees well with the mean daily losses expected for this group of subjects (1.0 mg). The conclusion can therefore be made that there are no major systematic errors of the present method to measure the total iron absorption from a mixed diet. In one series a comparison was made of the absorption of heme and nonheme iron from the meals. A significant correlation between the absorption of the two kinds of iron was found. However, a much greater fraction of the heme iron was absorbed (37%) than of the nonheme iron (5%). The absorption both from breakfast and lunch was in two series found to give a good prediction of the total daily nonheme iron absorption. One series was designed to compare the effect of two levels of iron fortification. There was a significant increase in iron absorption when the level of iron fortification of the meals was increased.

Absorption↗