Iron Revisited: Alternate-Day Oral Iron Supplementation in Endurance, Intermittent, and Power/Strength Athletes

Exclusion criteria:

1. Non-English speaking
2. Anemic (hemoglobin <120g/L)
3. Antibiotics use within 4 weeks prior to study enrollment
4. Regular prebiotic (fiber) or probiotic use within 4 weeks of study enrollment
5. Current laxative use
6. Are a smoker or use tobacco products
7. Consume >21 units of alcohol per week
8. Have donated blood in the previous 3 months
9. Have a BMI <16 but >30kg/m2
10. Are dieting for weight loss or are following a low carbohydrate diet
11. Have participated in another clinical trial within the 30 days preceding study enrollment.
12. 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.
13. Known history of thalassemia or thalassemia trait
14. Known inherited bleeding disorder
15. Major surgery in the past 3 months
16. Chronic use of Salicylates, aspirin, corticosteroids, or nonsteroidal anti-inflammatory drugs
17. 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
18. Have current musculoskeletal injuries that limit exercise capacity
19. 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
20. Orthopaedic issues that limit exercise ability
21. 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.)
22. Currently/last 3 months taking iron containing supplements.
23. 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:
o Abstinence or agrees to use contraception if planning to become sexually active
o Hormonal contraceptives including oral contraceptives, hormone birth control patch
o Vaginal contraceptive ring, injectable contraceptibes, or homone implant
o Barrier methods (e.g. condoms with spermicide, diaphragms with spermicide)
o Intrauterine devices
o Unwilling use contraception if engaged in heterosexual relationship
o Vasectomy of partner at least 6 months prior to screening
24. Additional exclusion criteria based on use of SIMBA capsules. Following is a summary of SIMBA capsules specific exclusion criteria:
o Prior gastrointestinal disease, surgery, or radiation treatment which, in the Investigator’s opinion, would lead to intestinal structuring 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.
o History of known structural gastrointestinal abnormalities such as structures or fistulas leading to mechanical obstruction
o 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.
o Organic motility disorder, including gastroparesis, intestinal pseudo-obstruction, systemic sclerosis, Ogilvie’s syndrome.
o History of oropharyngeal dysphagia, or other swallowing disorder with a risk of capsule aspiration
o Participants schedules for MRI
o Participants with history of less than 3 bowel movements per week
o Any prior fecal microbiota transplantation
o Drug use
25. 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.