Improving Iron Levels in Female Endurance, Intermittent, and Power/Strength Athletes Aged 16-35

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