Heme Iron vs Non-Heme Iron Supplements: A Canadian Guide
Short answer: heme iron comes from haemoglobin (the form in meat), while non-heme iron is the form in plants and in most supplements, including ferrous salts, bisglycinate and polysaccharide-iron complexes. According to the NIH Office of Dietary Supplements (ODS), vegetarians need more iron than people who eat animal products because non-heme iron is less bioavailable. ODS also says that heme iron polypeptides, carbonyl iron, iron amino-acid chelates and polysaccharide-iron complexes "might have fewer gastrointestinal side effects than ferrous or ferric salts". The evidence is hedged, and individual experience varies. Whichever form you consider, confirm low iron with a blood test first.
The forms compared
| Form | What it is | Absorption (as sources state) | Tolerability notes | Examples we carry |
|---|---|---|---|---|
| Heme iron polypeptide | Iron from haemoglobin (NFH's page names bovine haemoglobin) | Product pages describe a separate intestinal pathway from non-heme iron; we have not cited a trial | Meat-derived, so not for vegetarians or vegans. See the ODS wording above | HemeBoost Forte, OptiFer Alpha |
| Iron bisglycinate | Iron bound (chelated) to the amino acid glycine | Non-heme | NFH's page describes it as easier on the stomach than iron salts | NFH Iron SAP |
| Ferrous salts (fumarate, sulfate, gluconate) | Traditional iron salts | Non-heme. ODS: vitamin C enhances non-heme absorption, calcium can interfere | The Wampole label notes constipation and stomach upset are common; dark stools are normal | Wampole Ferrous Fumarate |
| Polysaccharide-iron complex | Iron bound to a carbohydrate; FeraMAX Pd uses a polydextrose-iron complex | Non-heme | FeraMAX's page describes its form as chosen to be easier on the stomach than many traditional salts. Take with meals | FeraMAX Pd Therapeutic 150 |
| Liposomal iron | Iron in phospholipid spheres (liposomes) | No independent source cited here | Ferosom's page says liposomes are intended to be gentle on the stomach | Ferosom Forte LCE |
Strengths are not interchangeable. FeraMAX Pd Therapeutic 150 lists 150 mg of elemental iron per capsule, Ferosom Forte 20 mg, and OptiFer Alpha 11 mg. Compare the elemental iron per dose on each label and follow your health professional's advice rather than the number on the front of the bottle.
Heme or non-heme: how to think about it
Heme iron is bound within a porphyrin ring, as in meat. Plants and iron-fortified foods contain non-heme iron only, and ODS reports that heme iron makes up roughly 10 to 15 percent of total iron intake in Western populations. For non-heme iron, Health Canada advises waiting 1 to 2 hours after a meal before tea, coffee or calcium supplements, and vitamin C helps absorption. Heme iron product pages say it is less affected by these, but we have not cited a trial comparing the forms, so we make no claim that one works better. If a standard iron has upset your stomach, ask your pharmacist about other forms.
What to look for on a Canadian label
Natural health products licensed by Health Canada carry an 8-digit Natural Product Number (NPN); drug-status iron products carry a Drug Identification Number (DIN). Check the number, the medicinal ingredient, the elemental iron per dose, the directions and the cautions. You can look the number up in Health Canada's Licensed Natural Health Products Database or Drug Product Database.
Canadian iron intakes (Health Canada DRIs)
The RDA meets the needs of almost all healthy people in a group; the tolerable upper intake level (UL) is the most from all sources that is unlikely to cause harm in healthy people. A few examples are below; see Health Canada's DRI reference values for elements for adult age groups, older women, breastfeeding and the full list.
| Group | RDA per day | UL per day |
|---|---|---|
| Children 9–13 | 8 mg | 40 mg |
| Teen males 14–18 | 11 mg | 45 mg |
| Teen females 14–18 | 15 mg | 45 mg |
| Pregnancy (19 and older) | 27 mg | 45 mg |
Health Canada's table notes the requirement is 1.8 times higher for vegetarians because of lower bioavailability. Therapeutic products can contain more than the UL per dose; those amounts are for a diagnosed deficiency under a health professional's care.
When to test, and the overload risk
Ask your doctor for a blood test, such as serum ferritin and a complete blood count, before starting iron. ODS notes that ferritin reflects the body's iron stores but can be affected by inflammation, so results are read alongside other measures. The body has no efficient way to excrete extra iron, so unneeded iron can accumulate, and iron should be avoided with haemochromatosis or other iron-overload conditions unless a doctor directs otherwise.
Keep iron out of reach of children. Accidental overdose of iron-containing products is a leading cause of poisoning in young children. If a child swallows iron, call your poison centre or 911 right away.
When to see a doctor or pharmacist
- Before starting iron, to confirm low iron and look for the cause.
- If you are pregnant or breastfeeding, take thyroid medication or antibiotics, or have a peptic ulcer or inflammatory bowel disease.
- For severe stomach pain, vomiting, vomiting blood, or ongoing constipation or diarrhea.
Related reading and products
Browse the Iron collection. Related guides: Ferrous Fumarate vs Bisglycinate vs Polysaccharide-Iron, Iron Deficiency Symptoms: When to Test, Not Guess and Beef Liver Supplements vs Iron Supplements.
Sources
- NIH Office of Dietary Supplements (U.S.; background). Iron: Fact Sheet for Health Professionals.
- Health Canada. Dietary Reference Intakes tables: Reference values for elements.
- Health Canada. Iron.
- Product details: the Healthy Hub product pages linked above.
This guide is general information, not medical advice. Ask your pharmacist or doctor about your own situation.