Female endurance athletes are susceptible to iron deficiency and this can impact their exercise performance. This study aims to assess the efficacy of a novel iron supplement in improving iron status, gut microbiome, and exercise performance in endurance-trained females.

Current iron supplements on the market are commonly associated with side effects including gastrointestinal distress, nausea, vomiting, and constipation. As a solution, the investigators have developed a novel delivery system for iron supplementation that overcomes many of these limitations. The goal of this study is to assess the efficacy of a yeast-iron complex in improving iron status, gut microbiome, and exercise performance in endurance-trained adolescent females (aged 14-17) with sub-optimal iron status. Participants will consume 40mg of elemental iron every second day for 8 weeks. Before and after supplementation, participants will be assessed for exercise capacity (VO2max), iron status, and the current state of the gut microbiome. each week during supplementation, participants will complete a survey in which they will report feelings of stress and recovery as well as gastrointestinal symptoms.

Inclusion Criteria:

• cis-gendered female 14-18 years old
• sub-optimal iron status (ferritin ≤45mcg/ L)
• At least 1 year past the age of menarche
• Engage in moderate to vigorous endurance activity for at least 3 hours a week

Exclusion Criteria:

• Supplemented with iron iron (>5mg/day), prebiotics, or probiotics in last 3 months
• antibiotic use in last 3 months
• - Energy availability >30 kcal/kg lean body mass