What is the aim of the review?

We wanted to investigate the effects of fortifying common staple foods with vitamin A, with or without other micronutrients, in populations two years of age and older. Staple foods used in public health fortification programmes have included refined sugar, edible vegetable oils and fats, rice, wheat flour, maize flours and corn meals, condiments and seasonings, and powdered or liquid milk. We searched for all the possible information on this question and found 10 eligible studies.

Key messages

Fortifiying staple foods with vitamin A plus other micronutrients may increase the serum retinol concentrations (an indicator of vitamin A stores in the body) and reduce the risk of subclinical vitamin A deficiency (those without clinical eye signs for risk of blinding undernutrition, detected through a serum/plasma retinol 70 μmol/L or less). However, adding vitamin A alone to the staple foods may have little or no effect on vitamin A status or deficiency.

What was studied in this review?

Vitamin A is an essential nutrient vital for good vision, cell growth, and immunity. Many people in low- and middle-income countries have vitamin A deficiency, especially young children, pregnant women, and women of reproductive age, who may not get enough to eat to cover their increased nutritional demands. Long-term deprivation of vitamin A could lead to visual impairment, blindness, common infections of the upper respiratory tract, diarrhoea, and measles.

There are several strategies to combat the vitamin A deficiency, such as supplementing the diet with vitamin A capsules, adding vitamins and minerals in powder form to energy-containing foods, eating more vitamin A-rich foods, and fortifying staple foods with vitamin A during processing. This review focused on the effects of fortifying staple foods with vitamin A for reducing vitamin A deficiency and improving the health of the general population older than two years of age.

What are the main results of the review?

We found 10 relevant studies (involving 4455 participants) from China, India, the Philippines, Bangladesh, Thailand, and Mexico. Three studies provided one study group with staple foods fortified with vitamin A alone, and another group with the same unfortified staple foods. Five studies compared staple foods fortified with vitamin A plus other vitamins and minerals versus the same unfortified staple food, and two studies compared staple foods fortified with vitamin A plus other vitamins and minerals versus no intervention.

No studies compared staple foods fortified with vitamin A versus no intervention.

Government agencies, private agencies, non-governmental organisations, the private sector, and academic institutions funded the studies. The source of funding does not appear to have distorted the results.

The effect of fortification of staple foods with vitamin A alone on vitamin A stores and on subclinical vitamin A deficiency is uncertain. It is uncertain whether this intervention might reduce clinical vitamin A deficiency (night blindness).

We are moderately confident that fortifying staple foods with vitamin A and other micronutrients may not improve vitamin A status. However, children and adolescents in low- and middle-income populations who eat foods fortified with vitamin A and other micronutrients may have a lower risk of subclinical vitamin A deficiency compared to those receiving unfortified staple foods.

We do not know how vitamin A fortification affects other health indicators, such as the rate of disease in the population, mortality, adverse effects, food intake, birth defects (for pregnant women), or breast milk concentration for lactating women. We considered six of the included studies to be of poor methodological quality.

The review authors searched for published studies up to July 2018.