THORNE Iron Bisglycinate, 25 mg Iron Supplement, 60 Capsules

Thorne Iron Bisglycinate is a single-ingredient iron supplement: 25 mg of elemental iron per capsule, as Ferrochel ferrous bisglycinate chelate. A 60-capsule bottle costs about $16 on Amazon and has a 4.7-star average from around 9,000 reviews.

Test before you take it

Iron isn't like vitamin D or B12. Your body has no easy way to get rid of extra iron, so it builds up, and too much can damage organs over time. Some people also have hemochromatosis, a genetic condition that makes them absorb too much iron already. So the right order is: see your doctor, get a ferritin test and a complete blood count, and take iron only if the results show you need it. Your doctor should also look for the reason your iron is low.

The NIH Office of Dietary Supplements sets the upper limit for adults at 45 mg of elemental iron a day. One capsule of this product is 25 mg. Doctors sometimes prescribe more for a while to treat diagnosed anemia, which is their call to make.

Keep it away from children. Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6.

What you get

Iron bisglycinate is a chelated form that Thorne describes as well absorbed and non-constipating. Many people do find it easier on the stomach than ferrous sulfate, which commonly causes constipation and cramps. The product is NSF Certified for Sport, so it's independently tested to match its label and screened for substances banned in sport. Supplements aren't FDA-approved before sale, so that certification is a useful quality check.

Take it apart from calcium, dairy, antacids, tea and coffee, which reduce absorption. Vitamin C helps. Iron can interfere with thyroid medication and some antibiotics, so ask your pharmacist about timing.

Who it's for

• Adults whose blood test shows low iron or low ferritin, and whose doctor suggests a supplement
• People who couldn't tolerate ferrous sulfate tablets
• Athletes who want a sport-certified product

Who should skip it

Anyone who hasn't been tested. Also men and post-menopausal women without a diagnosis, who rarely need extra iron, and anyone with hemochromatosis or another iron-overload condition.

Alternatives

For doctor-directed treatment, the Nature Made Iron 65 mg ferrous sulfate tablet is USP Verified and much cheaper, at a higher dose. A multivitamin like the Nature Made Multivitamin For Her includes a standard daily amount of iron for women who still have periods.

Read iron, B12, or vitamin D: which supplement for energy for how iron deficiency differs from the others, and why am I always tired for the wider picture.