Iron Absorption

Dietary Reference Intakes (DRIs) for iron are based on a relatively small number of studies in European populations. This research study will determine iron needs in a representative sample of adults living in the US using the iron isotope dilution technique. Following administration and equilibration of a stable iron isotope, participants will be followed for a 12 week study period. Blood will be collected every 4 weeks and the isotopic composition will be determined. Results will help update dietary iron guidelines making sure they better match the specific needs of the US population.

The purpose of this study is to determine the health impacts of consistent consumption of insect-fortified crackers among school-aged children in Madagascar. Specifically, in this RCT, the investigators will assess whether the insect-fortified crackers can improve the health status of Malagasy school children. The investigators' objectives are to: (1) Assess changes in gut microbiome composition that occur after 6 and 14 weeks of cracker consumption through 16S rRNA sequencing. (2) Assess changes in intestinal and systemic inflammation after 6 and 14 weeks of cracker consumption through quantification of fecal calprotectin, lactoferrin, myeloperoxidase (MPO), and alpha-1-antitrypsin (AAT) and circulating pro-inflammatory cytokines. (3) Assess changes in iron status after 14 weeks of cracker consumption through quantification of hemoglobin (Hb), inflammation-adjusted serum ferritin, and soluble transferrin receptor (sTfR).

Fifteen female study participants will be enrolled in a randomized crossover study to measure fractional and total zinc and iron absorption from four common bean (Phaseolus vulgaris) varieties with varying phytate and polyphenolic contents. Phytate, the storage form of phosphorus in plants, and polyphenols, which contribute to the varied colors of common beans, are natural components of the beans and can reduce zinc and iron bioavailability from these foods.

Iron is an essential micronutrient responsible for a whealth of biological processes of the human body. Iron plays a fundamental role especially in oxygen transport, by binding to hemoglobin in the blood circulation. Iron intake from the diet needs to be in balance the unavoidable losses that occur daily via different pathways. The recommended daily requirement of iron is based on the balance between absorption and losses and is calculated to maintain a balance so that the absorption equals losses. At higher altitudes, the absorption of iron may be higher due to adaptation mechanisms in response to low oxygen concentration, and to maintain a larger erytroid compartement. However, the long-term effects of altitude on iron balance are unknown. Filling this knowledge gap is important to better understand iron deficiency in populations living at high and moderate altitudes. Therefore, the investigators plan to study people that live at two different altitudes and measure iron absorption and losses over the long term. This will be useful to formulate specific recommendations for this population groups, to expand the knowledge base to better prevent iron deficiency in Switzerland but also worldwide. Participants will be asked to consume a dose of stable iron isotopes. After one year from isotope administration, the isotopes will be equally distributed in all body compartments and any change in the isotope abundance with the normal occurring body iron can be detected. From this point onwards, the investigators can observe the iron turnover and calculate iron absorption and losses per unit of time. At 4 different visits blood samples will be taken from each participant.

Reports from the Kenya Red Cross Society (KRCS) in Kwale County, southern Kenya, indicate a limited impact of Ready-to-Use Therapeutic Foods (RUTFs) on malnutrition or anemia. The current RUTF formulation may have an excessively high iron content. In severely acutely malnourished (SAM) children, iron cannot be properly absorbed, leading to life-threatening diarrhea. The overall aim of this project is to develop an improved RUTF treatment that addresses acute malnutrition and anemia in children, ensuring both safety and efficacy. Specifically, to assess the impact of malnutrition on fractional iron absorption (FIA) from RUTFs in children, by comparing healthy children to those with acute malnutrition and by tracking changes in FIA in malnourished children over the course of treatment.

This longitudinal study will examine the effects of repeated bouts of operational stress and limited recovery on integrated MPS, whole-body protein balance, iron absorption, and aerobic performance. Following baseline characterization measures, active adults (n=24) representative of normal weight phenotype (NW; n=12) and overweight phenotype (OW; n=12) will complete a 48h balance phase preceding two rounds of repeated 72h energy deficit exposure each immediately followed by a 48h recovery phase. NW cutoff will be defined ≤ 22% body fat for males and ≤ 32% body fat for females. OW cutoff will be defined as \>22% body fat for males and \>32% body fat for females. These body composition cutoffs are informed by the maximum allowable percent body fat standards outlined in current Army Regulation 600-9. Additional details for determining % body fat are outlined in the experimental procedures section of the protocol.

Iron requirements increase significantly during pregnancy. Current recommendations for iron intake in pregnant and lactating women (PLW) are mainly based on factorial estimates and extrapolated from non-PLW. High-quality quantitative data on iron requirements in PLW are lacking, particularly in Sub- Saharan Africa where anaemia and infections are common. The primary objective of this study is to use the stable iron isotope technique to determine iron requirements and assess iron absorption and losses in PLW living in Kenya. In this prospective observational study, we will enrol pregnant women in the first trimester (n = 250) from a previous study cohort (n=1000) who participated in an iron absorption study at least 12 months ago and received the stable iron (Fe) isotope 57Fe. This 57Fe has now distributed and equilibrated throughout the women's body iron. Once enrolled in the present study, following Kenyan guidelines, women will receive standard prenatal care, including routine daily iron and folate supplementation. We will collect venous blood samples in each trimester and at delivery, and during the first 6 months of lactation in the mothers and infants (heel prick samples). To directly assess dietary iron absorption, in a randomly selected subset of women (n=35), oral and intravenous stable iron isotope tracers (54Fe, 58Fe) will be administered in the 2nd and 3rd trimesters.