Hydrothermal treatment and malting of barley improved zinc absorption but not calcium absorption in humans.

OBJECTIVE: To study whether hydrothermal treatment or malting of barley (cv. Blenheim) improves zinc and calcium absorption in humans. DESIGN: : Two groups of 10 and 12 healthy subjects, respectively, were in a period of 2 months in a fasting state, served two single meals each containing porridge or breakfast cereals prepared from processed or unprocessed (control) barley (60 g). The meals included 200 g of milk, extrinsically labelled with (65)Zn and (47)Ca. Whole-body retention of both minerals was measured. SETTING: The study was carried out at the Department of Radiation Physics, Sahlgrenska University Hospital, Göteborg. SUBJECTS: The subjects were recruited among students at the Göteborg University. None dropped out. INTERVENTIONS: The activities of (65)Zn and (47)Ca were measured by whole-body counting four to five times over a 4-week period after each meal. RESULTS: Zinc absorption from hydrothermally treated barley porridge, containing 28 mg P as inositol tri- to hexaphosphates (InsP(3)-InsP(6)), was significantly higher (P<0.001) than from control porridge containing 111 mg P as InsP(3)-InsP(6), 25.2+/-6.9 vs 11.0+/-2.5% (n=12). Calcium absorption did not differ (P>0.05), 21.1+/-6.8 vs 19.5+/-4.7% (n=12). Zinc absorption from breakfast cereals of malted barley with phytase activity and containing 70 mg P as InsP(3)-InsP(6,) was significantly higher (P<0.05) than from flakes of barley, containing 108 mg P as InsP(3)- InsP(6) and no phytase activity, 22.9+/-5.8 vs 14.8+/-4.6% (n=10). The calcium absorption was 21.3+/-6.5 vs 18.5+/-4.3% (n=10) and did not differ significantly (P>0.05). CONCLUSION: Improvements of zinc absorption in breakfast meals can be achieved by optimised hydrothermal treatment or malting of barley. Calcium absorption was not influenced in the meals in this study. SPONSORSHIP: Supported by Semper AB, Sweden, Oy Lahden Polttimo, Finland, the SL-Foundation, Sweden, Swedish National Board for Industrial and Technical Development (NUTEK), the Nordic Industrial Foundation, Swedish Council for Forestry and Agricultural Research (SJFR, project no 50.0306/97).

Total energy expenditure in underweight patients with severe chronic obstructive pulmonary disease living at home.

AIM: The aim of the study was to assess total daily energy expenditure (TDE), as measured by doubly labelled water (DLW), and describe its components in home-living underweight patients with severe chronic obstructive pulmonary disease (COPD). METHODS: Basal metabolic rate (BMR) was measured prior to the study. Ten patients received DLW, followed by urine analysis by isotope ratio mass spectrometry from 10 standardised occasions during 15 days. Dietary intake was registered by each patient the first 7 days of the study. The patients were also interviewed about their physical activity pattern. RESULTS: Measured BMR was higher than predicted in five of the 10 patients using equations from WHO. Using disease-specific equations, estimated BMR was higher for male, but not for female COPD patients. The best estimation of BMR resulted from prediction including fat-free mass. TDE varied considerably between 5200 and 11,100 kJ. Physical activity level (PAL) ranged from 1.15 to 1.80. Energy intake varied between 4500 and 9100 kJ. In underweight patients with severe COPD, TDE is highly variable, ranging from 110 to 200 kJ/kg body weight. CONCLUSIONS: This is the first study assessing and describing total energy expenditure in underweight patients with severe COPD living at home. Energy requirement in the patient group cannot solely be calculated from prediction equations. BMR should be measured and physical activity level assessed.

Bioelectrical impedance variation in healthy subjects during 12 h in the supine position.

BACKGROUND AND AIM: Bioelectrical impedance analysis is used to assess human body composition. Studies have shown that meal ingestion and change of body posture affects bioelectrical impedance, but none has studied bioelectrical impedance variation in supine subjects. The aim was to examine the bioelectrical impedance variation in healthy subjects during 12 h in the supine position. METHODS: Bioelectrical impedance was measured 16 times during 12 h in 18 healthy subjects. An identical meal was given at breakfast, lunch, and dinner. RESULTS: Mean (standard deviation) impedance at 50 kHz increased from 558 (87) omega at study start to 584 (95) Omega at study end (P<0.05). Bioelectrical impedance is reduced after ingestion of the first meal, but not following the meals at 1230 and 1730. Calculated body fat content increased from a baseline mean (SD) of 21.7 (6.1) % body fat to 23.9 (6.7) % body fat at study end (P<0.05). CONCLUSIONS: Bioelectrical impedance increased during 12 h in supine subjects. The increase is probably explained by a shift in body fluids from the extremities to thorax during the day and the importance of strict measurement standardisation both in epidemiological studies and clinical practice is underlined.

Individual dietary intervention in patients with COPD during multidisciplinary rehabilitation.

UNLABELLED: Dietary intervention studies in COPD patients often are short-term inpatient studies where a certain amount of extra energy is guaranteed. The aim of this study was to evaluate the effect of an 1 year individual multifaceted dietary intervention during multidisciplinary rehabilitation. Eighty-seven patients with severe COPD, not demanding oxygen therapy were included, 24 of them served as controls. A dietary history interview was performed at baseline and at study end. Dietary advice given were based on results from the dietary history and socio-economic status. The intervention group was divided into three parts; NW: normal weight (dietary advice given aiming to weight maintenance), OW: overweight (weight-reducing advice) and UW: underweight (dietary advise based on an energy- and protein-rich diet). RESULTS: UW-group: Eighty-one per cent of the patients gained weight or kept a stable weight. OW-group: Fifty-seven per cent lost more than 2 kg NW-group: Seventy-six per cent kept a stable weight or gained weight. Increased dietary intake from baseline was seen for energy protein, carbohydrates and certain micronutrients (P < 0.05) in the UW group. Six minutes walking distance increased by approximately 20 m in both NW (P < 0.05) and UW patients. To conclude, slight, but uniform, indications of positive effects of dietary intervention during multidisciplinary rehabilitation was seen. Dietary intervention in underweight COPD patients might be a prerequisite for physical training.

Bioelectrical impedance: effect of 3 identical meals on diurnal impedance variation and calculation of body composition.

BACKGROUND: Bioelectrical impedance analysis (BIA) can be used for estimating body composition. Earlier studies showed that the ingestion of meals lowers bioelectrical impedance, but none studied the effect of repeated ingestion of an identical meal in narrow intervals on impedance measurements during 24 h. OBJECTIVES: The objectives were to study the effect on bioelectrical impedance of 3 identical meals and to compare the results from single-frequency BIA measurements with those from multiple-frequency BIA measurements. DESIGN: Bioelectrical impedance was measured 18 times during 24 h in 18 healthy subjects [10 women and 8 men; x +/- SD age: 31.5 +/- 11.7 y; body mass index (in kg/m(2)): 22.2 +/- 2.7]. An identical meal was given at breakfast, lunch, and dinner. RESULTS: Bioelectrical impedance decreased after ingestion of a standard meal (P < 0.05). The decrease in impedance lasted 2-4 h after each meal. The decrease was additive during the day, although it was more pronounced after the first meal because of the combined effect of rising from the supine position and meal ingestion. This is an important consideration when calculating body composition: percentage of body fat varied by 8.8% from the highest to the lowest measurement in women and by 9.9% from the highest to the lowest measurement in men. The bioelectrical impedance at 50 kHz was identical when measured with multiple frequencies or a single frequency. CONCLUSION: The ingestion of meals leads to an additive decrease in bioelectrical impedance and thus to a decrease in the calculated percentage of body fat.

Determination of the retention of 47Ca by whole-body counting.

Retention of intravenously or orally administered 47Ca in the human body are described by a two-parameter function. It is then sufficient to make only a few whole-body measurements to determine the retention function, avoiding faeces sampling and stool markers. Seven days after intake the non-absorbed calcium was excreted and the model agreed with the measured relative retention. Absorption of calcium could then, in some cases (e.g. comparative studies), be described by relative retention at the 7th day after intake.

Inositol phosphates with different numbers of phosphate groups influence iron absorption in humans.

BACKGROUND: Inositol hexaphosphate (IP(6)) is a well-known inhibitor of iron absorption, whereas the effects of the less-phosphorylated derivatives of IP(6) are less known. OBJECTIVES: The objective was to investigate the effects of inositol tri-, tetra-, and pentaphosphates (IP(3), IP(4), and IP(5), respectively) on iron absorption in humans. DESIGN: Iron absorption was measured in 5 experiments from single meals by extrinsic labeling with (55)Fe and (59)Fe and determination of whole-body retention and the erythrocyte uptake of isotopes. In experiments 1-3 the meals contained white-wheat rolls to which 10 mg P as IP(5), IP(4), or IP(3), respectively, was added. Inositol 1,2,6-triphosphate [Ins(1,2, 6)P(3)] and a mixture of isomers of IP(4) and IP(5) were studied. White-wheat rolls contained 10 mg P as IP(3) + IP(4) and 2 mg P as IP(5) + IP(6) in experiment 4 and 20 mg P as IP(3) + IP(4) and 3 mg P as IP(5) + IP(6) in experiment 5; inositol phosphates were obtained via fermentation of sodium phytate. Each experiment had 8-11 subjects. RESULTS: In experiment 1, iron absorption was reduced by 39%, whereas there was no significant effect on iron absorption in experiments 2 and 3. In experiments 4 and 5, iron absorption was reduced by 54% and 64%, respectively, suggesting that IP(3) and IP(4) contributed to the inhibitory effect. CONCLUSIONS: IP(5) has an inhibitory effect on iron absorption, whereas IP(3) and IP(4) in isolated form have no such effect. IP(3) and IP(4) in processed food contribute to the negative effect on iron absorption, presumably by binding iron between different inositol phosphates. To improve iron absorption from cereals and legumes, degradation of inositol phosphates needs to be to less-phosphorylated inositol phosphates than IP(3).

Improved zinc and iron absorption from breakfast meals containing malted oats with reduced phytate content.

The absorption of Zn or Fe from breakfast meals containing oat porridge prepared from malted and soaked oats and a control porridge made from untreated oats was measured in human subjects. The effect on Zn and Fe absorption of reducing the phytate content of oat-porridge meals was examined in each subject by extrinsic labelling of porridge with 65Zn and of bread rolls with 55Fe and 59Fe, and measuring whole-body retention and the erythrocyte uptake of isotopes. Each experiment comprised nine to ten subjects. The absorption of Zn from malted-oat porridge with a phytate (inositol hexaphosphate) content of 107 mumol was 18.3%, and significantly higher (P < 0.05) than from the control porridge containing 432 mumol phytate (11.8%). Fe absorption from the meal containing malted-oat porridge with 107 mumol phytate (Expt 2) was also significantly improved (P < 0.05) compared with that from the meal containing control porridge with 437 mumol phytate. The average increase in Fe absorption was 47%, or from 4.4 to 6.0%. In the breakfast meal containing malted porridge with 198 mumol phytate (Expt 3) the increase in Fe absorption was not significantly improved. Even though the phytate content was reduced to a greater extent in Expt 3 than Expt 2, the average increase in Fe absorption in Expt 3 was only 25% more than that from the meal containing control porridge (with 599 mumol phytate), depending on the higher absolute amount of phytate. In conclusion, an improvement in Zn and Fe absorption from oat products can be achieved by practising malting and soaking in the processing of oats. This may be of importance in the prevention of mineral deficiency in vulnerable groups.

Iron absorption from the whole diet: comparison of the effect of two different distributions of daily calcium intake.

The possibility of reducing calcium inhibition of iron absorption by decreasing calcium intake in lunch and dinner meals, which provided the most dietary iron, was examined in 21 healthy female volunteers. During a 10-d period, nonheme iron in all meals was extrinsically labeled with radioisotopic iron to a uniform specific activity. Iron absorption from two identical 10-d periods was compared when meals were labeled with two different iron radioisotopes and when the same amount of calcium (937 mg) was distributed in two ways, in either mainly breakfast and late evening meals or more evenly in all meals. About 30-50% more iron was absorbed when no milk or cheese was served with lunch or dinner. The difference was statistically significant. Median iron requirements (1.61 mg/d) calculated from body weight and menstrual iron losses agreed with the mean value of median iron absorption in the two 10-d periods (1.54 mg/d), which supports the validity of the present method. A reasonable separation of calcium and iron intakes would improve iron nutrition.

Inhibition of haem-iron absorption in man by calcium.

The inhibiting effect of Ca on non-haem-Fe absorption is well established. Present studies showed that Ca inhibited haem-Fe absorption to the same extent when the same amount of Ca (165 mg Ca as CaCl2) was added to a meal. Attempts were made to examine the mechanism for this inhibition in the present studies. Meat is the only known dietary factor influencing haem-Fe absorption. The present studies were designed to examine whether Ca interfered with the enhancing effect of meat on haem-Fe absorption. We found that the inhibition was the same whether biosynthetically radio-Fe-labelled haemoglobin was given in meals with or without meat. The haem-Fe absorption ratio with:without added Ca was 0.59 (SE 0.07) when Ca was added to a hamburger meal, and 0.52 (SE 0.03) when added to a wheat roll. These values were not significantly different (t 0.95; P = 0.35). The inhibition of haem-Fe absorption by Ca is, thus, a direct effect on the absorption of haem-Fe and not an indirect counteracting effect of the well-known enhancing effect of meat on haem-Fe absorption. Control studies were conducted to ensure that haem-Fe had not been degraded to non-haem-Fe during preparation of the foods. Since Ca inhibits the absorption of haem- and non-haem-Fe to the same extent, the present results strongly suggest that Ca interferes with the transport of Fe through the mucosal cell, and at a late stage, is common for haem- and non-haem-Fe transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory effect of oat products on non-haem iron absorption in man.

Oat products are increasingly used in human nutrition due to the rather high content of soluble fibre. Oat products, however, have a high content of phytate which may interfere with the absorption of non-haem iron. The iron balance situation is critical in several groups, especially in children, teenagers and women in their fertile years. It is therefore important to examine the effect of oat products on non-haem iron absorption in man. The present studies showed that oat bran and oat porridge markedly inhibited the absorption of non-haem iron. The inhibition can be explained by the high phytate content of oat products. This is partly due to a high resistance of oat phytate against exogenous phytase and partly to an inactivation of the endogenous phytase in oats caused by the usual heat treatment of oats which is made to prevent rancidity of oat lipids during storage. The inhibitory effect of oat products on iron absorption is sufficiently marked to be a serious consideration if such products are more regularly consumed.

Iron fortification of flour with a complex ferric orthophosphate.

The unexpectedly low bioavailability in humans of elemental iron powder prompted us to search for other Fe compounds suitable for Fe fortification of flour that fulfill the two requirements of insolubility in water (due to high water content of flour) and good bioavailability in humans. Systematic studies of compatibility, solubility, and bioavailability led to this study of a microcrystalline complex ferric orthophosphate (CFOP), Fe3H8(NH4)-(PO4)6.6H2O, a well-defined compound. This compound was labeled with 59Fe, and the native Fe in meals was labeled with 55FeCl3. The ratio of absorbed 59Fe to absorbed 55Fe is a direct measure of the fraction of CFOP that joins the nonheme Fe pool and that is made potentially available for absorption. The relative bioavailability of CFOP varied from 30% to 60% when labeled wheat rolls were served with different meals. The CFOP meets practical requirements of an Fe fortificant for flour well, with regard to both compatibility and bioavailability in humans.

Is there a physiological role of vitamin C in iron absorption?

Nonheme iron usually constitutes more than 90% of the dietary iron. Its absorbability is a resultant of the balance between factors enhancing and inhibiting the absorption. Ascorbic acid is the most potent enhancer, and is the same for native and synthetic AA. The enhancing effect is strongly dose related (log dose/effect), and is different for different meals probably mainly due to varying content of inhibitors in the meals. AA also increases the iron absorption from simple meals with no known inhibitor, probably because AA impairs the formation of unavailable iron complexes with ligands normally present in the gastrointestinal lumen. The effect of AA is so unequivocal and marked that it must be considered as a physiological factor essential for the absorption of dietary iron.