Stacy Sims on Iron
4 episodes · 8 references · 2026
- Sims views iron as critical for oxygen transport and athletic performance, emphasizing that low iron causes fatigue and flatness - Recommends highly bioavailable forms (iron bisglycinate or carbonyl iron) every other day, timed around training to avoid hepcidin interference - No evidence of personal consumption; cautions against unnecessary supplementation due to iron overload risks
Benefits
- Iron enables heme groups to carry oxygen; low iron means insufficient oxygen circulation, causing fatigue and flatness - Vitamin D supports iron absorption and helps maintain iron stores - Post-training vitamin D supplementation reduces hepcidin, optimizing iron availability
Best Practices
- Use iron bisglycinate or carbonyl iron — the two most bioavailable forms — every other day to boost ferritin - Take iron before training or at night, away from training sessions, to avoid hepcidin interference - Preferably dose first thing in the morning on non-training days for optimal absorption
Cautions
- Hepcidin rises with inflammation post-training for ~5 hours, decreasing iron absorption during that window - Over-absorption of iron presents identically to iron deficiency — fatigue and flatness — making unnecessary supplementation counterproductive - Do not supplement iron unless bloodwork confirms a deficiency
“We want to have [Vitamin D] after training to help reduce hepcidin so that we can have optimal iron.”
Protein, Creatine, Vitamin D & Beta Alanine | Which Supplements Matter After 40?
“Iron is responsible for allowing those heme groups to carry oxygen. If we have low iron, then we don't have enough oxygen circulating throughout the body, so you feel very flat and tired.”
Supplements Women Actually Need: Dr. Stacy Sims Explains Why Bloodwork Isn’t Enough
“It's supplementing every other day with a very high bioavailable iron, with either carbonyl or glycinate, then we're really able to boost that ferritin.”
Supplements Women Actually Need: Dr. Stacy Sims Explains Why Bloodwork Isn’t Enough
“How do I supplement? Supplement before training or at night away from training.”
Supplements Women Actually Need: Dr. Stacy Sims Explains Why Bloodwork Isn’t Enough
$0.03/ct
$4.67 total
$0.08/ct
$7.60 total
$0.18/ct
$16.10 total
$0.26/ct
$45.94 total
