Iron Bisglycinate

Thorne Iron Bisglycinate is the iron supplement people tend to reach for after cheaper iron upset their stomach. Each small capsule supplies 25 mg of elemental iron (139% of the Daily Value) as Ferrochel ferrous bisglycinate chelate, with only a cellulose capsule, microcrystalline cellulose, leucine and silicon dioxide alongside. It is NSF Certified for Sport, gluten-, dairy- and soy-free, and ranks among Amazon's top iron supplements with nearly 9,000 ratings.

The form is the selling point. NIH notes that iron amino-acid chelates might cause fewer gastrointestinal side effects than ferrous or ferric salts, and that supplemental iron at 45 mg a day or more commonly causes nausea and constipation. One capsule stays below that 45 mg adult upper limit. Buyers and creators consistently describe it as easier on the stomach than iron they tried before, although a minority still report nausea, especially on an empty stomach.

Iron supplements are for people who need them. Women aged 19 to 50 need 18 mg a day and adult men only 8 mg, and people with hereditary hemochromatosis should avoid iron supplements, so a blood test that includes ferritin is the right starting point. Take it apart from calcium and at least four hours away from levothyroxine; acid-reducing drugs can lower iron absorption, and iron doses of 25 mg or more can reduce zinc absorption.

At $16 for 60 capsules (about 27 cents a day), it costs more than generic ferrous sulfate, which is the main point reviewers debate. Store it securely: accidental iron overdose is a leading cause of fatal poisoning in children under six.