🧪 Lactoferrin

Lactoferrin is a protein that binds iron tightly. It is found in milk, saliva, tears and nasal mucus. The most is in human colostrum — about 7 g per litre — and about 1 g/L in mature breast milk. Lactoferrin takes iron away from bacteria and takes part in protecting mucous membranes.

A red iron-containing protein in cow's milk was noticed in 1939, but isolating it in pure form long proved impossible; it was studied in detail around 1960 and received the name "lactoferrin" in 1961. Its antibacterial action, linked to iron binding, was recorded at the same time.

Measurements differ widely. In a Chinese study (Nutrients, 2018), the medians in human milk were 3.16 g/L in colostrum, 1.73 g/L in transitional milk and 0.90 g/L in mature milk. The protein in milk is saturated with iron only to about 10%. Cow's milk contains much less of it, and measurements differ between studies.

The best data are for premature babies. A 2020 Cochrane review (12 studies, 5,425 infants) found that lactoferrin in feeding reduces late-onset sepsis (typical relative risk 0.82) but has no effect on necrotizing enterocolitis or on mortality; the certainty of the evidence is low.

Lactoferrin or iron, lactoferrin or colostrum? Lactoferrin is not iron: it is a protein that binds iron, and in milk it is saturated with iron only to about 10%. Colostrum is the first milk, and lactoferrin is one protein in it; human colostrum holds the most lactoferrin, about 7 g per litre against about 1 g/L in mature breast milk. Cow’s milk contains much less than human milk, and measurements differ between studies. The best evidence so far concerns premature babies, not healthy adults.

Lactoferrin appears on labels as “lactoferrin” or “bovine lactoferrin”, usually on products sold as food supplements in capsules, tablets or drops. That category is not subject to the same control as medicines, so quality can vary. You will meet such products in pharmacies, health-food shops and online sellers of supplements. A label does not prove that the product does what its wording suggests; the best data are for premature babies, and a doctor is the person to ask.

Why it matters to you. Lactoferrin supplements are widely sold, but their quality can vary, because they are not subject to the same control as medicines. The protective role of this protein is mainly for the infant, together with other substances in breast milk; ask a doctor about supplements.