Product Description
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.
- Gluten free
- Sport Tested: NSF Certified for Sport®
Supplement Facts
60 Servings
Serving Size: 1 Capsule
Serving Per Container: 60
| Amount Per Serving | ||
|---|---|---|
| % Daily Value* | ||
| Iron (Bisglycinate) 25mg | ** | |
* Percent Daily Values are based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs.
** Daily Value (DV) not established
Always Happy Promise: Don't like a product? Tell us within 30 days of receipt and we'll make it right and make you happy. Here at The Feed, we want you to love your experience and the sports nutrition products you purchase. If, for any reason, you are not satisfied with your nutrition specific purchase, tell us.
We do not accept returns on food items that have been opened, but we will issue a store credit if you are unsatisfied. In the event of a return, you must first contact us before sending back a return shipment.
Consumable products over $40 receive a 50% store credit. This includes specialty nutrition products such as ketones or supplements/vitamins.
Thorne Iron Bisglycinate FAQ's
Everything you need to know before getting started.
Daily supplementation is recommended if your ferritin is below 35 ng/mL. Athletes need 1.5x more iron than non-athletes due to training-induced losses. Get your ferritin tested every 8-12 weeks to monitor levels and adjust supplementation accordingly.
Iron bisglycinate is elemental iron bonded to the amino acid glycine. This chelated form is absorbed 4-5x more efficiently than ferrous sulfate (drugstore iron) and doesn't cause the constipation, nausea, or stomach upset common with traditional iron supplements. Your gut recognizes the glycine carrier and absorbs it readily.
Absolutely. Vegetarian and vegan athletes have iron needs up to 1.8x higher than omnivores because plant-based iron (non-heme) is absorbed less efficiently. This chelated iron bisglycinate provides the bioavailable elemental iron your body needs without relying on dietary heme iron from meat.