You hit the workout but recovery feels slower. Your legs feel heavy three days in a row. That fatigue you can't shake? It might not be overtraining. Nearly one in three athletes has low iron stores, and most don't know it until performance tanks. Here's what endurance athletes forget: you need 1.5 times more iron than non-athletes. Every footstrike, every interval, every training block depletes your stores.

Thorne Iron Bisglycinate is the athlete's iron supplement that actually works without wrecking your stomach.

What Makes It Different

Bisglycinate Chelate = Maximum Absorption, Zero Gut Issues This isn't ferrous sulfate from the drugstore that leaves you constipated and nauseous. Iron bisglycinate bonds with glycine, an amino acid your gut recognizes and absorbs efficiently. You get the iron your red blood cells need without the GI distress that makes you quit supplementing.

NSF Certified for Sport = Clean for Competition Every batch tested for 290+ banned substances. No surprises in drug testing. Just 25mg of pure, bioavailable iron that keeps you compliant and competitive.

Built for Female Athletes and Endurance Training Women lose iron through menstruation. Endurance athletes lose it through foot strike hemolysis and gut microbleeding. Vegetarians miss it from their diet. This formula addresses all three with a dose that restores ferritin levels without overdoing it.

The Science Made Simple

Your red blood cells carry oxygen to working muscles using hemoglobin, and hemoglobin needs iron to function. When iron stores (ferritin) drop below 30-35 ng/mL, your body can't produce enough hemoglobin efficiently. The result: reduced oxygen delivery, slower recovery, persistent fatigue. Iron bisglycinate provides 25mg of elemental iron that your body absorbs at rates up to 4.5 times higher than conventional iron supplements, restoring stores without triggering the inflammatory gut response that tanks absorption.

How to Use Thorne Iron Bisglycinate

Daily maintenance: Take 1 capsule daily on an empty stomach (or as directed by your sports dietitian). Take with vitamin C to boost absorption, but keep it away from coffee or calcium supplements which block uptake.

This is the iron supplement trusted by 100+ professional sports teams and chosen by EF Pro Cycling's medical staff for their athletes. When ferritin testing revealed widespread deficiency across their roster, this was the protocol that brought levels back to performance range without a single athlete reporting GI side effects.

This isn't just another iron pill that sits in your cabinet after three days of stomach issues. This is the absorption-optimized, gut-friendly iron that keeps your red blood cells fueling every training session.

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