An interventional study of labeled iron solution and labeled iron solution and ascorbic acid in Obesity, sponsored by Swiss Federal Institute of Technology. Completed at 1 site in Switzerland. Open to female participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2013-10-14.
Sponsored by Swiss Federal Institute of Technology · Not applicable, Interventional, and Basic science
A total of 75 subjects will be recruited for this study (25 normal weight, 25 overweight, 25 obese). In each subject blood volume will be determined using the minimally invasive carbon monoxide-rebreathing method (substudy 1) and iron absorption will be measured from a test meal labeled with stable iron isotopes. The effect of ascorbic acid on iron absorption will further be determined using a second labeled test meal (substudy 2). In addition, inflammation, hepcidin and iron status will be determined. In order to study the effect of body fat content on blood volume and iron absorption weight and height will be measured, and body fat will de determined by dual energy X-ray absorptiometry.
Obesity has repeatedly been shown to be a risk factor for iron deficiency. The reason for this is believed to be reduced iron absorption as a result of increased circulating hepcidin concentrations. However, the direct interactions between body fat mass, iron absorption, inflammation and hepcidin have not been studied to date. Whether the low iron absorption in obese subjects could be overcome by conventional methods to increasing iron absorption, e.g. the addition of ascorbic acid and whether a reduction of inflammation could improve absorption is further unclear. For the calculation of fractional iron absorption from oral doses of stable iron isotopes an estimation of blood volume is required. Several equations to estimate blood volume from weight and height or calculated body surface area or volume are available, but have rarely been validated or used in obese subjects. The aim of the described study is therefore: 1) to determine blood volume using the carbon monoxide-rebreathing method over a large BMI range and to use those values to validate existing blood volume equations; 2) to measure iron absorption, hepcidin and inflammation in relation to BMI and body fat and 3) to assess the effect of ascorbic acid on iron absorption.
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Exclusion Criteria:
Test meal (bread with honey) with a labeled iron solution
Dietary Supplement: labeled iron solution · Dietary Supplement: labeled iron solution and ascorbic acid
Test meal (bread with honey) with a labeled iron solution and ascorbic acid
Dietary Supplement: labeled iron solution · Dietary Supplement: labeled iron solution and ascorbic acid
labeled iron as ferrous sulfate (6mg/test meal)
labeled iron as ferrous sulfate plus ascorbic acid (6mg:30mg /test meal)
Fractional iron absorption from the isotopically labeled test meals.
Iron absorption will be determined by incorporation of labeled iron into erythrocytes, 14 days after the administration of the last test meal containing labeled iron (stable isotope technique). Based on the shift of the iron isotope ratios in the blood samples and the amount of iron circulating in the body, the amounts of isotopic label iron present in the blood 14 days after the test meal administration will be calculated based on the principles of isotope dilution and considering that the iron isotopic labels are not monoisotopic. Circulating iron will be calculated based on blood volume as determined by carbon monoxide-rebreathing. For calculation of fractional absorption, 80% incorporation of the absorbed iron into red blood cells will be assumed.
Time frame: Baseline
Hemoglobin mass will be measured with the carbon monoxide-rebreathing method.
Blood volume will be calculated from hemoglobin mass and compared to values determined by the different equations.
Time frame: Baseline
This study is completed, as verified in Oct 2013. You cannot join it, but the record below documents what was studied.
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Swiss Federal Institute of Technology