Skip to main content
OpenTrials
Active, Not Recruiting

NCT Number: NCT04526678

Oslo Footballplayers Iron Supplementation and Training (FIT) Study

The aim of the study is to characterize the diet and iron status of young female elite football players and examine the relationship between iron intake, iron status, hemoglobin levels, intestinal health and sports performance. In addition, the effects of low-dose iron supplements on iron stores will be investigated and whether such supplementation affects intestinal health, microbiota composition and biomarkers for oxidative stress.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

Key information

Conditions

Athletes Endurance Performance Hemoglobin Intestinal Health Iron Microbiota

Age range

16 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Norwegian University of Life Sciences

Ås, 1433, Norway

About this study

Iron deficiency can lead to fatigue and anemia. Because iron is necessary for the formation of new blood cells (hematopoiesis), it is an extensive practice internationally among athletes to take iron supplements in the belief that this will improve endurance performance and oxygen transport capacity by increasing red blood cell production. Although iron intake in menstruating women has shown to reduce the prevalence of anemia and iron deficiency as well as increasing hemoglobin values and iron stores. However iron supplementation increases the risk of iron excess and can result in undesirable effects such as constipation and abdominal pain as well as negative impact on intestinal epithelial permeability and increase in oxidative stress. Because iron is important for the replication and survival of almost all bacteria, with few exceptions, the intake of iron also affect the composition of the intestinal bacteria. Not surprisingly, both high and low iron levels affect the composition of the microbiota in the gut.

It is not known if young menstruating Norwegian female athletes cover their need for iron via the diet or whether extra intake in the form of a low-dose supplement could be beneficial in terms of hemoglobin levels and sports performance. Because iron preparations are not prescription and are sold in pharmacies, health food stores and larger grocery stores, this can lead to uncritical intake of iron. Since the use of iron preparations has been documented to be widespread in foreign sports environments, it is important to both characterize the iron status of Norwegian athletes and at the same time examine the beneficial value of iron supplements on sports performance as well as monitoring effects on microbiota composition and intestinal health.

The aim of the study is therefore to characterize the diet and iron status of young female elite football players and examine the relationship between iron intake, iron status, hemoglobin levels, intestinal health and sports performance. In addition, the effects of low-dose iron supplements will be investigated in relation to iron stores, hemoglobin levels and sports performance and whether such supplementation affects intestinal health, microbiota composition and biomarkers for oxidative stress.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Female elite football players from two selected football clubs

Exclusion criteria

  • Pregnancy
  • Medical conditions that are worsened by taking iron supplements
  • Already taking iron supplements

Treatment and study plan

Iron supplement (27mg)

Dietary Supplement

The participants will be randomized to an intervention group or a control group. The intervention group will ingest 27mg iron daily for three months.

Primary outcomes

  1. Diet composition

    Time frame: 3 months

    Diet composition will be assessed using digital 7 day dietary records.

  2. Iron intake

    Time frame: 3 months

    Iron intake will be calculated based on average daily intake of iron according to the digital 7 day dietary recordings.

  3. Serum Iron

    Time frame: 3 months

    Iron status will be assessed by analyzing serum iron (µmol/L)

  4. Serum transferrin

    Time frame: 3 months

    Iron status will be assessed by analyzing serum transferrin (µmol/L)

  5. Serum ferritin

    Time frame: 3 months

    Iron status will be assessed by analyzing serum ferritin (µg/L)

  6. Hemoglobin levels

    Time frame: 3 months

    hemoglobin (Hb) (g/dl) will be analyzed in whole blood (EDTA) using an automated hematology analyzer.

  7. LPS binding protein

    Time frame: 3 months

    -Intestinal health will be measured using biomarkers of intestinal leakage in serum and feces such as sLPS binding protein (LBP) (ug/ml)

  8. Neutrophil gelatinase-associated lipocalin

    Time frame: 3 months

    -Intestinal health will be measured using biomarkers of intestinal leakage in serum and feces such as fecal neutrophil gelatinase-associated lipocalin (NGAL) (ng/g feces)

  9. Serum cytokines

    Time frame: 3 months

    -Intestinal health will be measured using serum biomarkers of systemic inflammation (e.g. serum cytokines such as IL-1, IL-6, and TNF-α pg/ml).

  10. Sports performance

    Time frame: 3 months

    Sports performance specific for football will be be measured using the Yo-Yo Intermittent Recovery Test (YYIR1).

  11. Differential counts

    Time frame: 3 months

    Differential counts (% of WBC) will be analyzed in whole blood (EDTA) using an automated hematology analyzer.

  12. Ferric reducing ability of plasma

    Time frame: 3 months

    -Oxidative stress will be assessed measuring the ferric reducing ability of plasma (FRAP)

  13. Diacron reactive oxygen metabolites

    Time frame: 3 months

    -Oxidative stress will be assessed measuring biomarkers of total oksidativ stress e.g. diacron reactive oxygen metabolites (dROM).

  14. Microbiota composition

    Time frame: 3 months

    -Microbiota composition will be analyzed mainly using 16S rRNA gene sequencing. The main effect of the intervention on the microbiota will be tested based on crude alpha and beta diversity indices but we will also apply advanced multivariate methods.

Sponsors and collaborators

Lead sponsor

Norwegian University of Life Sciences

Other

Collaborators

  • Norwegian Olympic Sports Centre
  • Norwegian School of Sport Sciences
  • University of Oslo

Registry information

Official study title

Iron Intake, Iron Status, Intestinal Health and Endurance Performance - Effects of Iron Supplementation in Young Female Football Players - a Pilot Study

Acronym: Oslo-FIT

Important dates

Study start
2020
Primary completion
2020
Study completion
2030
First posted
Aug 26, 2020
Registry last updated
May 23, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.