This randomized, double-blind, active-controlled trial will evaluate the effects of human lactoferrin supplementation combined with low-dose iron on iron status, aerobic performance, and lactate metabolism in exercising women with low ferritin. Approximately 30 healthy, menstruating women aged 18-45 years with serum ferritin \<35 µg/L will be enrolled in an 8-week intervention. Participants will be stratified by baseline ferritin status and randomized to receive 100 mg lactoferrin + 5 mg iron, 300 mg lactoferrin + 5 mg iron, or placebo + 5 mg iron daily. Primary outcomes include changes in ferritin and hematological parameters. Secondary outcomes include VO₂peak, time to exhaustion, and blood lactate responses during standardized treadmill testing. This study will determine whether lactoferrin enhances iron homeostasis and improves physiological and performance outcomes in exercising women with low iron stores.
Iron deficiency is one of the most common micronutrient deficiencies in women, particularly among those who are physically active. Suboptimal iron status can impair oxygen transport, mitochondrial function, and exercise performance. Although oral iron supplementation is commonly used, gastrointestinal side effects may reduce adherence and limit effectiveness. Lactoferrin, an iron-binding glycoprotein, has emerged as a potential adjunct strategy to improve iron regulation and tolerability. This study will investigate whether supplementation with human recombinant lactoferrin in combination with low-dose iron improves iron status and exercise-related outcomes in exercising women with low ferritin. Approximately 30 healthy, menstruating women aged 18-45 years with serum ferritin \<35 µg/L will be recruited. Participants will be stratified by baseline ferritin status (\<20 µg/L or 20-35 µg/L) and randomized in a double-blind, parallel-group design to receive one of the following for 8 weeks: 100 mg lactoferrin + 5 mg iron 300 mg lactoferrin + 5 mg iron Placebo + 5 mg iron Participants will complete six study visits including screening, baseline, and follow-up assessments at weeks 2, 4, 6, and 8. Assessments will include venous blood sampling for iron-related biomarkers and hematological parameters, as well as inflammatory and metabolic markers. Aerobic performance will be evaluated using VO₂peak testing and time-to-exhaustion treadmill protocols with serial blood lactate measurements. Additional measures include gastrointestinal symptoms, menstrual symptoms, quality of life, and perceived recovery. Daily supplementation compliance and adverse events will be monitored throughout the intervention. This trial will provide insight into the role of lactoferrin as an adjunct to iron supplementation for improving iron homeostasis and performance outcomes in active women.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
30
Human recombinant lactoferrin administered at a dose of 100 mg daily for 8 weeks.
Human recombinant lactoferrin administered at a dose of 300 mg daily for 8 weeks.
Oral iron supplementation provided at a dose of 5 mg daily for 8 weeks.
Exercise and Performance Nutrition Laboratory
Saint Charles, Missouri, United States
RECRUITINGChange in Serum Ferritin Concentration
Serum ferritin concentration will be assessed via venous blood samples to evaluate changes in iron storage over the intervention period.
Time frame: Baseline, Weeks 2, 4, 6, and 8
Change in Hemoglobin
Hemoglobin concentration measured from venous blood samples. Higher values indicate improved oxygen-carrying capacity.
Time frame: Baseline, Weeks 2, 4, 6, and 8
Change in Hematocrit
Percentage of red blood cells in blood volume. Higher values indicate increased red cell mass.
Time frame: Baseline, Weeks 2, 4, 6, and 8
Change in Red Blood Cell Count
Total number of red blood cells per unit volume of blood. Higher values indicate increased erythropoiesis.
Time frame: Baseline, Weeks 2, 4, 6, and 8
Change in Serum Iron
Serum iron concentration measured from venous blood samples.
Time frame: Baseline, Weeks 2, 4, 6, and 8
Change in Total Iron Binding Capacity
Measure of blood's capacity to bind iron with transferrin.
Time frame: Baseline, Weeks 2, 4, 6, and 8
Change in Transferrin Saturation
Percentage of transferrin bound to iron. Higher values indicate improved iron availability.
Time frame: Baseline, Weeks 2, 4, 6, and 8
Change in Hepcidin Concentration
Circulating hepcidin levels reflecting iron regulatory activity. Lower levels generally indicate increased iron availability.
Time frame: Baseline, Weeks 2, 4, 6, and 8
Change in VO₂Peak
VO₂Peak will be assessed using a graded treadmill test with indirect calorimetry to evaluate maximal aerobic capacity. Higher values indicate improved aerobic performance.
Time frame: Baseline, Week 4, and Week 8
Change in Time to Exhaustion During Treadmill Testing
Time to exhaustion will be measured during a standardized treadmill protocol. Longer time to exhaustion indicates improved endurance performance.
Time frame: Baseline, Week 4, and Week 8
Change in Ventilatory Threshold (%VO₂Peak)
Ventilatory threshold will be expressed as a percentage of VO₂Peak during graded exercise testing. Higher values indicate improved submaximal aerobic efficiency.
Time frame: Baseline, Week 4, and Week 8
Change in Blood Lactate Concentrations During Exercise
Capillary blood lactate will be measured at rest and during standardized treadmill stages (70%, 80%, 85%, and 90% VO₂Peak). Lower lactate at a given workload indicates improved metabolic efficiency.
Time frame: Baseline, Week 4, and Week 8
Change in Gastrointestinal Symptoms Rating Scale (GSRS) Score
The GSRS is a 15-item questionnaire assessing gastrointestinal symptoms, scored on a 7-point Likert scale (1 = no discomfort, 7 = very severe discomfort). Lower scores indicate fewer symptoms.
Time frame: Baseline, Week 4, and Week 8
Change in Menstrual Symptoms Questionnaire Score
The MSQ-24 assesses severity and frequency of menstrual-related symptoms. Higher scores indicate greater symptom burden.
Time frame: Baseline, Week 4, and Week 8
Change in Health-Related Quality of Life (SF-36) Score
The SF-36 evaluates multiple domains of health-related quality of life. Higher scores indicate better perceived health status.
Time frame: Baseline, Week 4, and Week 8
Change in Perceived Recovery Scale Score
Perceived recovery will be assessed using a 0-10 scale, where 0 indicates very poorly recovered and 10 indicates fully recovered. Higher scores indicate better recovery status.
Time frame: Baseline, Weeks 2, 4, 6, and 8
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