Size: 60 capsules
Thorne's Advanced Iron Complex (formerly Ferrasorb) delivers iron bisglycinate chelate — a highly bioavailable, stomach-friendly form of iron — alongside folate (as 5-MTHF), vitamin B12, and vitamin C to support red blood cell formation and healthy iron status. Formulated for individuals with increased iron needs, including menstruating women, athletes, or those managing dietary gaps.
Why It's Worth Considering: The iron bisglycinate chelate form is gentler on the GI tract than ferrous sulfate, and pairing it with 5-MTHF and active B12 addresses the full nutritional picture for iron-deficiency-related fatigue support.
| Feature | Bisglycinate (gentle) | Ferrous Sulfate | Ferrous Fumarate | Heme Iron |
|---|---|---|---|---|
| Absorption | High (chelated) | Moderate | Moderate | Highest (animal-derived) |
| GI Side Effects | Minimal | Common (constipation) | Moderate | Minimal |
| Best For | Sensitive stomachs | Budget, proven | Higher elemental iron | Maximum absorption |
| Take With | Empty stomach OK | Vitamin C required | Vitamin C helps | Anytime |
Iron bisglycinate (Ferrochel) is the best-tolerated form with high absorption and minimal GI side effects. Ferrous sulfate is the most studied but commonly causes constipation and nausea. Heme iron polypeptide has the highest absorption rate but is animal-derived.
Non-chelated iron forms (ferrous sulfate, fumarate) are poorly absorbed — the unabsorbed iron irritates the gut lining and slows peristalsis. Chelated forms (bisglycinate) are absorbed more completely, leaving less unabsorbed iron in the gut. Taking vitamin C improves absorption and reduces GI side effects.
Separate iron from calcium, zinc, magnesium, and dairy by 2+ hours (they compete for absorption). Separate from thyroid medication by 4+ hours. DO take iron WITH vitamin C (doubles absorption). Avoid taking with coffee or tea (tannins reduce absorption by 60%).
Get a complete iron panel: serum ferritin (most sensitive — optimal is 50-100 ng/mL), serum iron, TIBC, and transferrin saturation. Symptoms of deficiency: fatigue, cold hands/feet, pale skin, brittle nails, shortness of breath, brain fog, and restless legs. Ferritin below 30 ng/mL warrants supplementation in most cases.
† These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
