Iron Glycinate

Most people come to bisglycinate after another iron didn't agree with them, so these are the questions our naturopaths ask in store before you switch. They start with whether iron is the right answer at all.

A good fit if

• An iron study or ferritin test has shown your stores are low, and your doctor agrees you should top them up
• A plain iron salt left you constipated, nauseous or with stomach pain, and you stopped taking it
• You eat a lot of wholegrains, legumes, tea or coffee and find it hard to keep them away from your dose
• You'd rather have a form you can stick with than give up on a course halfway through

Check with us first if

• You take levothyroxine, tetracycline or quinolone antibiotics, or levodopa. Iron binds to all of these in the gut and reduces their effect, so you need to space the doses apart.
• You take a proton pump inhibitor. Reducing stomach acid blunts your response to iron tablets, and a chelate isn't a guaranteed way around that.
• You're pregnant or breastfeeding. Most of the evidence on how well this form is tolerated comes from pregnancy trials, but your pregnancy care team should still set the dose.
• You have coeliac disease or inflammatory bowel disease, you've had stomach or bowel surgery, or you give blood regularly. Your absorption or stores are affected and the cause needs looking into.
• You already take a multivitamin, pregnancy multivitamin or greens powder. Check the iron content first, because chelated iron is common in all three.
• Your gut symptoms didn't settle after switching. That points back to the dose, the timing or the diagnosis rather than the compound.
• You take any prescription medicine at all. Check with your doctor, pharmacist or our naturopaths first.

• Iron (II) glycinate: Schedule 1 item 2727. Best known for: The name most Australian bisglycinate products are actually listed under. Absorption: Labels often state 120 mg of the compound as equal to 24 mg of actual iron. Typical use: Once-a-day tablets and capsules at the 24 mg limit, often paired with vitamin C.
• Iron (II) bisglycine sulfate trihydrate: Schedule 1 item 2726. Best known for: A separately listed compound that isn't the same substance, despite the similar name. Absorption: A bisglycine sulfate complex rather than the simple chelate; each has its own Schedule 1 entry. Typical use: Uncommon on Australian labels; it's worth checking which of the two a product names.
• Iron amino acid chelate: Schedule 1 item 2729. Best known for: The umbrella term many bisglycinate products are declared under. Absorption: Schedule 1 caps iron at 25 per cent of the chelate, so the compound always weighs more than the iron in it. Typical use: The wording to expect on a retail pack; the branded chelate name usually appears in the marketing.
• Ferrous sulfate. Best known for: The standard iron salt, and the one most published trials compare against. Absorption: About 20 per cent iron by weight, released as free ferrous iron all at once. Typical use: The form most people are given first and most often give up on; it has its own guide here.

Reference values. You'll find the full NHMRC Recommended Dietary Intakes for iron on our iron page. They apply to iron itself rather than to this compound. On a bisglycinate label, the elemental (actual) iron figure is the only number worth comparing between products.

Typical supplemental range. Australian listed medicines can provide no more than 24 mg of iron a day, whatever the compound, and most bisglycinate-only products are at that limit, usually with 120 mg of iron (II) glycinate per tablet. This is where comparing it with ferrous sulfate needs care. Overseas, a standard ferrous sulfate tablet gives far more elemental iron than a typical bisglycinate capsule, so trials comparing the two often don't use matching doses. In the review we used, the ferrous sulfate groups took 40-100 mg, while the bisglycinate groups in pregnancy most often took 15-30 mg. Australia's 24 mg limit evens out that difference, so here the real comparison is how well you tolerate it, not strength.

Upper level. The NHMRC Upper Level of Intake is 45 mg a day for adults, and NIH notes that 45 mg a day or more of supplemental iron may cause nausea and constipation. Every Australian listed medicine is well below that limit by law.

Worth knowing. Choosing a gentler form doesn't answer the first question, which is whether you need iron at all. A ferritin result answers that, a symptom doesn't. Doses used to correct a diagnosed deficiency are above the over-the-counter limit and should be managed by your doctor. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Cashew nuts, oil roasted: about 2 mg per 28 g (non-haem iron, the category the chelate is designed to mimic)
• Baked potato, flesh and skin: about 1 mg per medium potato
• Raisins, seedless: about 1 mg per quarter cup
• Wholemeal bread: about 1 mg per slice, though its phytates also limit how much is absorbed

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• Children. Never give it without a doctor's direction. Accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under six, and an iron overdose can cause death (Better Health Channel).
• If you think a child has swallowed iron, it's an emergency: call the Poisons Information Centre on 13 11 26 or 000.
• Haemochromatosis, iron overload conditions or repeated blood transfusions. Don't take it; your body can't get rid of extra iron, whatever the form.
• Treating tiredness yourself without a blood test. Healthdirect advises that an iron study is the only reliable test.
• Gentler doesn't mean free of side effects. Constipation, nausea and dark stools still happen on chelated iron.
• The evidence on tolerability is rated very low quality, with high variation between studies and signs of publication bias, and the bisglycinate groups often used lower iron doses than the forms they were compared with.
• Levothyroxine, tetracycline and quinolone antibiotics, and levodopa. Iron binds to them in the gut and makes them work less well (NIH).
• Pregnancy and breastfeeding. Your antenatal team should set the dose.
• 45 mg a day or more increases gut side effects (NIH); it's also the NHMRC adult Upper Level.
• Coeliac disease, inflammatory bowel disease, gut surgery or regular blood donation. These can change absorption or run down your iron stores.
• Severe tummy pain, ongoing vomiting, or black tarry stools with pain. Stop and get medical advice.
• If you take prescription medicines, check with your doctor, pharmacist or one of our naturopaths before you start.