Assess the effectiveness of iron-fortified flour on iron status.

Systematic review and meta-analysis.

Argentina, Australia, Azerbaijan, Bangladesh, Brazil, Cameroon, Chile, China, Costa Rica, Côte d’Ivoire, Denmark, India, Iran, Jordan, Kazakhstan, Kenya, Kuwait, Mongolia, Morocco, Norway, South Africa, Sri Lanka, Tajikistan, Thailand, UK, USA, Uzbekistan, Venezuela, Vietnam, and Zambia.

Fifty-two articles (ninety-four trials) were examined. The main target groups were women, children, and infants/toddlers. The effects of different types of iron-fortified flour (wheat, maize, rice, soy, and beans) on iron status were examined.

A random effects analysis of before–after studies showed that iron-fortified flour led to significant increases of mean haemoglobin level (3·360 g/l; 95 % CI: 0·980, 5·730) and mean serum ferritin level (4·518 µg/l; 95 % CI: 2·367, 6·669); significant decreases of anaemia (−6·7 %; 95 % CI: −9·8 %, −3·6 %) and iron deficiency (ID) (−10·4 %; 95 % CI: −14·3 %, −6·5 %); but had no significant effect on iron deficiency anaemia (IDA). A random effects analysis of controlled trials indicated that iron-fortified flour led to significant increases of mean haemoglobin level (2·630 g/l; 95 % CI: 1·310, 3·950) and mean ferritin level (8·544 µg/l; 95 % CI: 6·767, 10·320); and significant decreases of anaemia (−8·1 %; 95 % CI: −11·7 %, −4·4 %), ID (−12·0 %; 95 % CI: −18·9 %, −5·1 %), and IDA (−20·9 %; 95 % CI: −38·4 %, −3·4 %).

Flour fortification with iron is an effective public health strategy that improves iron status of populations worldwide.