Recruiting

Iron Supplements

Sponsor:

University of Calgary

Code:

NCT06942208

Conditions

Iron Deficiency

Eligibility Criteria

Sex: Female

Age: 16 - 35

Healthy Volunteers: Accepted

Interventions

Low-dose iron (ferrous sulfate)

Yeast-bound iron (ferrous sulfate)

High-dose iron (ferrous sulfate)

Study Details

Brief summary:

The goal of this clinical trial is to learn if different types and doses of oral iron supplements can improve iron levels, athletic performance, and gut health in young female athletes with low iron stores. The main questions it aims to answer are:

  • Does a low dose of yeast-bound iron improve iron status better than traditional iron supplements?
  • Do the different iron supplements cause fewer or more gastrointestinal (stomach) symptoms?
  • How do iron supplements affect exercise performance and gut bacteria?

Researchers will compare three types of iron supplements:

  • A low-dose iron supplement (40 mg)
  • A low-dose yeast-bound iron supplement (40 mg)
  • A high-dose iron supplement (150 mg)

This will help researchers find out which type of supplement is most effective and easiest on the stomach.

Participants will:

  • Take one of the three assigned iron supplements every other day for 12 weeks
  • Complete fitness tests before and after the study, including cycling and jumping tests
  • Give blood samples to measure iron levels
  • Provide stool and intestinal samples to study gut bacteria
  • Swallow a SIMBA capsule before and after the study to collect a sample from the small intestine
  • Complete regular online surveys about sleep, stress, menstrual cycles, and gut symptoms

Conditions

Iron Deficiency

Study ID

NCT06942208

Start date

Mar 26, 2026

Status verified date

Apr, 2026

Completion date

Sep, 2026

Anticipated

Primary completion date

Sep, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: Female

Age: 16 - 35

Healthy Volunteers: Accepted

Inclusion Criteria:

  • Biologically female athlete
  • Age 16-35
  • At least one year past the age of menarche
  • Complete and pass the Get Active Questionnaire (GAQ)
  • Suboptimal ferritin levels (≤50 mcg/L)
  • Provide informed consent to participate in study
  • Activity level based on Participant Classification Framework (McKay et al., 2022)

  • Tier 3: Highly Trained / National Level
  • Tier 4: Elite / International Level
  • Energy availability >30 kcal/kg LBM
  • Have access to a smartphone, tablet, or computer
  • Able to swallow a capsule sized 25mm length and 8mm width (i.e. large dose omega 3 pill)

Exclusion Criteria:

  • Non-English speaking
  • Anemic (hemoglobin <120g/L)
  • Regular prebiotic (fiber) or probiotic use within 4 weeks of study enrollment
  • Current laxative use
  • Are a smoker or use tobacco products
  • Consume >21 units of alcohol per week
  • Have donated blood in the previous 3 months
  • Have a BMI <16 but >30kg/m2
  • Are dieting for weight loss or are following a low carbohydrate diet
  • Have participated in another clinical trial within the 30 days preceding study enrollment.
  • Known allergy of hypersensitivity to any ingredient, including non-medicinal ingredients, such as iron, yeast, cellulose, or maltodextrin
  • Are taking medications known to affect cardiovascular or metabolic responses to exercise such as beta-blockers, anti-coagulants etc. as assessed by the Principal Investigator
  • Known history of thalassemia or thalassemia trait
  • Known inherited bleeding disorder
  • Major surgery in the past 3 months
  • Chronic use of Salicylates, aspirin, corticosteroids, or nonsteroidal anti-inflammatory drugs
  • Have any of the following conditions: renal or gastrointestinal disorders, autoimmune disease, metabolic disease, heart disease, vascular disease, rheumatoid arthritis, diabetes, poor lung function, uncontrolled blood pressure, dizziness, thyroid problems, or any other health conditions that are being treated and deemed to be able to significantly interfere with study intervention and assessment in the opinion of the Principal Investigator and Qualified Investigator
  • Have current musculoskeletal injuries that limit exercise capacity
  • Self-identifying with any kidney or gastrointestinal issues, metabolic disorders, cardiac conditions, vascular illnesses, rheumatoid arthritis, diabetes, compromised lung function, unregulated blood pressure, episodes of dizziness, thyroid complications, or any other health conditions under treatment that might potentially interfere with the study results
  • Orthopaedic issues that limit exercise ability
  • Currently/last 3 months taking prescription medications that are known to affect iron absorption (i.e. Antacids/PPIs (e.g., omeprazole), H2 Blockers (e.g., ranitidine), Tetracycline Antibiotics (e.g., doxycycline), Quinolone Antibiotics (e.g., ciprofloxacin), Cholestyramine, Colchicine, Methyldopa.)
  • Currently taking levodopa or levothyroxine
  • Currently/last 3 months taking iron containing supplements
  • Are pregnant or lactating or planning to become pregnant for the duration of the study. All participants must agree to use a medically approved method of birth control for the duration of the study. All hormonal birth control must have been in use for a minimum of three months. Acceptable methods of birth control include:

  • Abstinence or agrees to use contraception if planning to become sexually active
  • Hormonal contraceptives including oral contraceptives, hormone birth control patch
  • Vaginal contraceptive ring, injectable contraceptives, or hormone implant
  • Barrier methods (e.g. condoms with spermicide, diaphragms with spermicide)
  • Intrauterine devices
  • Non-heterosexual lifestyle or agrees to use contraception if planning on changing to heterosexual partner(s)
  • Vasectomy of partner at least 6 months prior to screening

Additional exclusion criteria based on use of SIMBA capsules. Following is a summary of SIMBA capsules specific exclusion criteria:

  • Currently pregnant, planning to become pregnant, or breastfeeding
  • Prior gastrointestinal disease, surgery, or radiation treatment which, in the Investigator's opinion, would lead to intestinal structuring, narrowing, or obstruction with a risk of capsule non-excretion, including, e.g. achalasia, eosinophilic esophagitis, any IBD, or previous esophageal, gastric, small intestinal, or colonic surgery. Appendectomy or cholecystectomy more than 3 months before the screening visit is acceptable.
  • History of known structural gastrointestinal abnormalities such as structures or fistulas leading to mechanical obstruction
  • Have any gastrointestinal inflammatory diseases, including ulcerative colitis, Crohn's disease, microscopic colitis.
  • Use of any medication in the week prior to the screening study visit, unless part of regular treatment, that could substantially alter gastrointestinal motor function (e.g. opioids, prokinetics, anticholinergics, GLP-1 analogues); laxative use is allowed if it is kept unchanged in the week prior to the study visit. Proton pump inhibitors (PPIs) are allowed provided a wash-out period of 48 hours is respected before swallowing the SIMBA capsules and PPI treatment is resumed only 4 hours thereafter.

  • Prokinetic (stimulate muscle contractions, Metoclopramide, Domperidone, Prucalopride, etc.) use. If you are not using prokinetics to treat SIBO, then you may be eligible after a 2-week washout period, and willing to not use prokinetics for the study duration.
  • Unable to stop using laxatives or prokinetic medications for 4 days before the study procedure (breath test). Laxatives can be resumed after the test is conducted.
  • Have used antibiotics (except for topical use) in the previous 12 weeks. You may be eligible to participate once a 12-week washout is completed
  • Regular use of probiotics, prebiotics, or synbiotics (including food and drinks containing added probiotics and/or probiotic yogurts with live, active cultures)
  • Have digestive problems that slow or stop food from moving properly, like a slow stomach, blocked intestines, or stiffened tissues
  • Suffer from celiac disease (treated or untreated)
  • Organic motility disorder, including gastroparesis, intestinal pseudo-obstruction, systemic sclerosis, Ogilvie's syndrome
  • History of oropharyngeal dysphagia, or other swallowing disorder with a risk of capsule aspiration
  • Have had a cancer diagnosis or treatment within the past year (non-melanoma skin cancers are acceptable)
  • Have trouble swallowing, which could cause a risk of choking on a capsule
  • Participants scheduled for an MRI at any time during the study. You may be eligible to participate once your MRI procedure is completed.
  • Have constant constipation (IBS-C) defined as a history of less than 3 bowel movements per week
  • Any prior fecal microbiota transplantation
  • Drug use
  • Suffer from alcohol or drug abuse
  • Females of childbearing potential will be asked about their likelihood of being pregnant, based on factors such as recent sexual activity or use of contraception. Their self-reported confirmation of non-pregnancy will be accepted unless they express uncertainty. In cases of doubt, a urine beta-HCG pregnancy test will be required for confirmation. If you become pregnant during the course of the study, you should stop taking the supplement immediately and inform the investigators. If you are using a supplement that the investigators have deemed to not interfere with the study's intervention or assessment (e.g. vitamins, omega-3, creatine monohydrate etc.), you will be permitted to continue taking these supplements. In all cases, participants will be instructed to not change the dose of the taken supplement or introduce a new supplement unless it is medically recommended.

Study Design

Enrollment

36 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

active comparator: Low dose iron supplement

This supplement consists of encapsulated ferrous sulphate (40 mg elemental iron).

experimental: Low dose iron supplement bound to yeast

Low dose iron (40 mg elemental iron) in the form of yeast-bound iron, specifically Lalmin® Fe10. This supplement consists of encapsulated ferrous sulphate complexed with inactivated Saccharomyces cerevisiae (nutritional yeast).

active comparator: High dose iron supplement

This supplement consists of encapsulated ferrous sulphate (150 mg elemental iron).

Interventions

Low-dose iron (ferrous sulfate)

Encapsulated low-dose ferrous sulphate (40mg elemental iron)

Yeast-bound iron (ferrous sulfate)

Encapsulated yeast-bound low-dose ferrous sulphate (40mg elemental iron)

High-dose iron (ferrous sulfate)

Encapsulated high-dose ferrous sulphate (150mg elemental iron)

Primary outcome measure

  • Iron status blood markers [ Time Frame: Baseline ]
  • Iron status blood markers [ Time Frame: 4 weeks ]
  • Iron status blood markers [ Time Frame: 8 weeks ]
  • Iron status blood markers [ Time Frame: 12 weeks ]
  • Gut microbiota [ Time Frame: Baseline ]
  • Gut microbiota [ Time Frame: 12 weeks ]

Central Contacts and Locations

Central contacts

Lauren Hundseth

(306) 380-5898lauren.hundseth@ucalgary.ca

Locations

University of Calgary

Recruiting

Calgary, Alberta, Canada, T2N 1N4

Contacts

Jane Shearer

(403) 220-3431jshearer@ucalgary.ca

More Information

Sponsor

University of Calgary

Last update posted

Apr 17, 2026

Last verified

Apr, 2026

Keywords

  • iron
  • iron deficiency
  • athletic performance
  • female athlete
  • iron supplements
  • ferritin
  • hemoglobin
  • gastrointestinal
  • microbiome
  • Exercise test
  • Yeast
  • Saccharomyces cerevisiae
  • ferrous sulphate
  • ferrous sulfate
  • Body composition
  • exercise

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of Calgary on 2026-04-17.