Iron Absorption

Iron deficiency is the most common nutrient deficiency worldwide and the single most treatable cause of fatigue. Absorption is tightly regulated by hepcidin, which rises with inflammation and with recent iron intake — which is why taking iron every day can paradoxically absorb less total iron than taking it every other day. Understanding the levers matters most for menstruating women, plant-based eaters, endurance athletes and anyone with gastrointestinal blood loss.

Take iron on alternate days rather than daily — this keeps hepcidin low and increases fractional absorption meaningfully. Take it on an empty stomach if tolerated, or with vitamin C: 100 mg ascorbic acid, or a glass of orange juice, with the dose. Avoid tea, coffee, milk and calcium supplements within an hour either side, since polyphenols and calcium are potent inhibitors. Cook in cast iron and pair plant iron sources with vitamin C-rich foods. Soaking, sprouting and fermenting legumes and grains reduces phytate and improves absorption. Retest ferritin at 8-12 weeks, and always investigate the cause of iron deficiency in men and postmenopausal women rather than simply replacing it.

• •Alternate-day rather than daily iron dosing
• •100 mg vitamin C with iron-containing meals
• •Separate tea and coffee from iron by one hour
• •Separate calcium supplements from iron
• •Soak or sprout legumes and grains
• •Include haem iron sources if not vegetarian
• •Cook in cast iron