AthletesOslo-FITNCT04526678
Oslo Footballplayers Iron Supplementation and Training (FIT) Study
A study testing Iron supplement (27mg) in people with Athletes and Iron, run by Norwegian University of Life Sciences at 1 site in Norway.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 16 years and older, women onlyHealthy volunteers can take part
- Conditions the study is for
- Athletes, Iron, Endurance Performance
- What is being tested?
- Iron supplement (27mg)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 23 participants
- Where
- 1 siteNorway
- Study dates
- 19 Aug 2020to 3 Dec 2020
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 16 years and older
- Women only
- Healthy volunteers accepted
- Child, Adult, Older adult
Who may be able to join
- Female elite football players from two selected football clubs
Who cannot join
- Pregnancy
- Medical conditions that are worsened by taking iron supplements
- Already taking iron supplements
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Iron Intake, Iron Status, Intestinal Health and Endurance Performance - Effects of Iron Supplementation in Young Female Football Players - a Pilot 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.
Read the detailed description
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.
- Conditions
- Athletes, Iron, Endurance Performance, Hemoglobin, Intestinal Health, Microbiota
- Being tested
- Iron supplement (27mg)
- Keywords
- oxidative stress, football
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
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.
| Study group | Role | What they receive |
|---|---|---|
| Iron supplements | Experimental | The intervention group will ingest 27 mg iron supplement per day for three months while the control group will not ingest iron supplements. Receives: Dietary Supplement: Iron supplement (27mg) |
| Control group | No intervention | The control group will not ingest iron supplements. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Diet composition
Diet composition will be assessed using digital 7 day dietary records.
Measured: 3 months
Iron intake
Iron intake will be calculated based on average daily intake of iron according to the digital 7 day dietary recordings.
Measured: 3 months
Serum Iron
Iron status will be assessed by analyzing serum iron (µmol/L)
Measured: 3 months
Serum transferrin
Iron status will be assessed by analyzing serum transferrin (µmol/L)
Measured: 3 months
Serum ferritin
Iron status will be assessed by analyzing serum ferritin (µg/L)
Measured: 3 months
Hemoglobin levels
hemoglobin (Hb) (g/dl) will be analyzed in whole blood (EDTA) using an automated hematology analyzer.
Measured: 3 months
LPS binding protein
-Intestinal health will be measured using biomarkers of intestinal leakage in serum and feces such as sLPS binding protein (LBP) (ug/ml)
Measured: 3 months
Neutrophil gelatinase-associated lipocalin
-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)
Measured: 3 months
Serum cytokines
-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).
Measured: 3 months
Sports performance
Sports performance specific for football will be be measured using the Yo-Yo Intermittent Recovery Test (YYIR1).
Measured: 3 months
Differential counts
Differential counts (% of WBC) will be analyzed in whole blood (EDTA) using an automated hematology analyzer.
Measured: 3 months
Ferric reducing ability of plasma
-Oxidative stress will be assessed measuring the ferric reducing ability of plasma (FRAP)
Measured: 3 months
Diacron reactive oxygen metabolites
-Oxidative stress will be assessed measuring biomarkers of total oksidativ stress e.g. diacron reactive oxygen metabolites (dROM).
Measured: 3 months
Microbiota composition
-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.
Measured: 3 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Aug 2020
- Study start19 Aug 2020
- Primary completion3 Dec 2020
- Study completion3 Dec 2020
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AthletesStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- The intervention group will ingest 27 mg iron supplement per day for three months while the control group will not ingest iron supplements.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 23 participants (actual)
Sponsor and investigators
- Lead sponsor
- Norwegian University of Life Sciences
- Sponsor type
- University, hospital or other
- Collaborators
- Norwegian School of Sport Sciences, University of Oslo, Norwegian Olympic Sports Centre
- Responsible party
- Principal investigator, Siv K Bohn, Norwegian University of Life Sciences
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04526678
- Sponsor's protocol ID
- 969159570_KBM_SKB2020
- Acronym
- Oslo-FIT
- Status last verified
- Aug 2026
- First submitted
- 13 Aug 2020
- Last updated
- 11 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: An IPD sharing plan is not ready for the project
Study at a glance
From the registry record, last updated by the sponsor on 11 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Iron Intake, Iron Status, Intestinal Health and Endurance Performance - Effects of Iron Supplementation in Young Female Football Players - a Pilot Study
- ClinicalTrials.gov ID
- NCT04526678
- Acronym / sponsor ID
- Oslo-FIT / 969159570_KBM_SKB2020
- Conditions
- Athletes, Iron, Endurance Performance, Hemoglobin, Intestinal Health, Microbiota
- Keywords
- oxidative stress, football
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 23 participants (actual)
- Lead sponsor
- Norwegian University of Life SciencesUniversity, hospital or other
- Collaborators
- Norwegian School of Sport Sciences, University of Oslo, Norwegian Olympic Sports Centre
- Study start
- 19 Aug 2020 (actual)
- Primary completion
- 3 Dec 2020 (actual)
- Study completion
- 3 Dec 2020 (actual)
- First posted
- 26 Aug 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
- Model description
- The intervention group will ingest 27 mg iron supplement per day for three months while the control group will not ingest iron supplements.
| Arm | Type | Receives |
|---|---|---|
| Iron supplements | Experimental | Dietary Supplement: Iron supplement (27mg)The intervention group will ingest 27 mg iron supplement per day for three months while the control group will not ingest iron supplements. |
| Control group | No intervention | –The control group will not ingest iron supplements. |
Who may qualify
- Ages
- 16 years and older
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (1 listed)
- Female elite football players from two selected football clubs
Key exclusion criteria (3 listed)
- Pregnancy
- Medical conditions that are worsened by taking iron supplements
- Already taking iron supplements
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Iron supplement (27mg)The participants will be randomized to an intervention group or a control group. The intervention group will ingest 27mg iron daily for three months. | Dietary supplement | Iron supplements |
Primary outcome
Diet composition
Time frame: 3 months
Diet composition will be assessed using digital 7 day dietary records.
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.
Serum Iron
Time frame: 3 months
Iron status will be assessed by analyzing serum iron (µmol/L)
Serum transferrin
Time frame: 3 months
Iron status will be assessed by analyzing serum transferrin (µmol/L)
Serum ferritin
Time frame: 3 months
Iron status will be assessed by analyzing serum ferritin (µg/L)
Hemoglobin levels
Time frame: 3 months
hemoglobin (Hb) (g/dl) will be analyzed in whole blood (EDTA) using an automated hematology analyzer.
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)
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)
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).
Sports performance
Time frame: 3 months
Sports performance specific for football will be be measured using the Yo-Yo Intermittent Recovery Test (YYIR1).
Differential counts
Time frame: 3 months
Differential counts (% of WBC) will be analyzed in whole blood (EDTA) using an automated hematology analyzer.
Ferric reducing ability of plasma
Time frame: 3 months
-Oxidative stress will be assessed measuring the ferric reducing ability of plasma (FRAP)
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).
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.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Aug 2026.
- Individual participant dataSharing planned: Undecided. An IPD sharing plan is not ready for the project
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Iron supplement (27mg) in people with Athletes and Iron, run by Norwegian University of Life Sciences at 1 site in Norway.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 11 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Norway. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Diet composition (time frame: 3 months). The study lists 14 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Aug 2026.