Determination of a Dose-dependent Effect of GOS on Iron Absorption, and Addition of Vitamin C

Iron is an important mineral in our body and fulfills essential functions such as for example oxygen transport from the lungs to the tissues. Iron deficiency is still the most common and widespread nutritional disorder in the world according to WHO. Common iron supplements all have their limitations in terms of availability and compatibility. Prebiotic fibers, such as galacto-oligosaccharides (GOS), selectively enhance growth of beneficial colonic bacteria. Prebiotics in general enhance the production of short-chain fatty acids (SCFAs) and thereby decrease luminal pH. Through the reduction in pH, prebiotics can enhance absorption of minerals such as calcium and magnesium and they have been proposed to potentially improve iron absorption.

In a recent iron absorption study in adult women with low iron stores in our lab (publication under review), we found that 15 g of GOS given with an iron supplement in the form of iron fumarate acutely increased iron absorption when given with water and a bread based meal. The dose of 15 g of GOS was tolerated well by the participants. As a follow up to the study mentioned above, we want to investigate: 1) if acute iron absorption is affected by lower doses of GOS; 2) whether this acute effect occurs for other commonly used iron compounds as well, such as iron sulphate and iron phosphate; and 3) if there are potential interactions on absorption with other enhancers of iron absorption, such as vitamin c.

Inclusion criteria

• Female, 18 to 45 years old
• SF levels <30 µg/L
• Normal body Mass Index (18.5-24.9 kg/m2)
• Body weight <70 kg
• Signed informed consent

Exclusion criteria

• Severe anaemia (Hb < 80 g/L)
• Elevated CRP >10.0 mg/L
• Any metabolic, gastrointestinal kidney or chronic disease such as diabetes, renal failure, hepatic dysfunction, hepatitis, hypertension, cancer or cardiovascular diseases (according to the participants own statement)
• Continuous/long-term use of medication during the whole studies (except for contraceptives)
• Consumption of mineral and vitamin supplements within 2 weeks prior to 1st supplement administration, including pre- and-or probiotics supplements (excluding foods and beverages with life cultures such as yoghurt, raw milk cheese and kombucha)
• Blood transfusion, blood donation or significant blood loss (accident, surgery) over the past 4 months
• Difficulties with blood sampling
• Use of antibiotics over the past month
• Known hypersensitivity to iron supplements in the given amount, GOS, or lactose
• Women who are pregnant or breast feeding
• Women who intend become pregnant during the course of the study
• Lack of safe contraception, defined as: Female participants of childbearing potential, not using and not willing to continue using a medically reliable method of contraception for the entire study duration, such as oral, inject-able, or implantable contraceptives, or intrauterine contraceptive devices, or who are not using any other method considered sufficiently reliable by the investigator in individual cases
• Known or suspected non-compliance, drug or alcohol (more than 2 drinks/day) abuse -
• Smokers (> 1 cigarette per week)
• Inability to follow the procedures of the study, e.g. due to language problems, self-- reported psychological disorders, etc. of the participant
• Enrollment of the investigator, his/her family members, employees and other dependent persons