Ferrous bisglycinate

What it is

Ferrous bisglycinate is an iron salt in which iron is bound to the amino acid glycine, a chelated form used as an oral iron supplement. Iron is the core of haemoglobin, so supplying it lets the marrow rebuild red blood cells and refill the body's iron stores. It is used for iron deficiency, with or without anaemia.

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

• Deficiency

Approved uses differ by country — some of these may be off-label or unapproved where you live.

What to know while taking it

Iron is absorbed best on an empty stomach, and vitamin C taken alongside improves uptake further, while tea and coffee bind iron in the gut and blunt absorption. Calcium carbonate with D3 competes with iron for the same absorption pathway, and iron interferes with levothyroxine, so those are kept well apart in the day. Response is tracked through ferritin, haemoglobin and transferrin saturation rather than by how one feels, since stores refill slowly after the blood count has normalised. Dark stools are expected and are not bleeding.

When to see a doctor

Persistent stomach pain, vomiting, or an inability to tolerate iron at all is worth reviewing, as is a thyroid condition that becomes unstable after iron is added. Iron deficiency that does not correct on treatment, or that returns after it, needs a doctor to look for the cause of the loss.

Worth knowing

• Vitamin C improves absorption
• Tea and coffee block absorption

Markers to watch

• Ferritin
• Hemoglobin
• Transferrin saturation