expert opinion

The impact of micronutrient fortification on health

October 15, 2013

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Centre of Excellence in Women & Child Health, Aga Khan University, Karachi, Pakistan

“In the early 20th century, salt iodization began in Switzerland; vitamin A-fortified margarine was introduced in Denmark in 1918; and in the 1930s, vitamin A-fortified milk and iron and B-complex flour was introduced in a number of developed countries. These fortification strategies are now almost universal in the developed world and increasingly deployed in many middle-income countries. The WHO categorizes food fortification strategies into three possible approaches: mass, targeted, and market driven (1). Mass fortification involves foods that are widely consumed, such as wheat, salt, sugar; targeted approaches fortify foods consumed by specific age groups like infant complementary foods; and the market-driven approach is when a food manufacturer fortifies a specific product for a parti-cular consumer group. Food vehicles commonly used can be grouped into three broad categories: staples (wheat, rice, oils), condiments (salt, soy sauce, sugar), and processed commercial foods (noodles, infant complementary foods, dairy products).

Food fortification is an attractive public health strategy and has the advantage of reaching wider at-risk population groups through existing food delivery systems, without requiring major changes in existing consumption patterns. Compared with other interventions, food fortification may be cost-effective and, if fortified foods are regularly consumed, has the advantage of maintaining steady body stores (2). Relatively few of these programs have been adequately evaluated to assess their impact on population health. Our systematic review singled out a total of 201 randomized controlled trials and observational studies in order to identify all available evidence for the impact of fortification interventions. Studies were included on the con-dition that food was fortified with a single, dual or multiple micronutrients and that the impact of fortifi-cation was analyzed on the health outcomes and relevant biochemical indicators of women and children. The review shows that, overall, staple foods have been the primary choice of fortification as they are widely consumed by the population, whereas processed foods and cereals have been chosen when infants were the target population. Iodine fortification almost exclusively used salt as a traditional and proven delivery method, folate fortification was commonly employed with the use of grains or grain products, and milk has been the carrier of choice for vitamin D and calcium.

Most national programs analyzed were from developed countries and data from the developing world were relatively scarce. However, where available, the results showed comparable benefits. This scarcity of studies from developing countries is due to the fact that national fortification programs require large resources; robust scientific and research facilities are required to identify the ideal food, micronutrient compound and industrial support. The experience of commodities such as pre-fortified ready-to-use fortified foods indicates that global procurement and supply as well as local production is possible.

Effects of food fortification in children

A meta-analysis of studies using foods – mainly baby formula, cow’s milk and complementary baby foods as well as curry powder, fish sauce and soy sauce in Asian countries – fortified with iron demonstrated a sig-nificant increase in hemoglobin concentration, serum ferritin levels and reduction in anemia. The findings were consistent for the various age groups (infants, preschool and school children), countries (lower, lower middle, upper middle and higher income countries) and baseline micronutrient status (deficient and normal populations). A few studies reported a positive effect on cognitive functions.

The analysis showed a consistent positive effect of zinc fortification of formula feeds and milk (for infants) or cereals (for school children) on increasing serum zinc levels. The impact on weight gain was non-significant across all the various age groups while the effect on height gain was significant only for infants with very low birth weight.

Analysis of the results from randomized controlled trials showed that fortification of milk with vitamin D and calcium significantly increased serum concentration of 25-hydroxyvitamin D3 and reduced serum concent-ration of parathyroid hormone (known to enhance the release of calcium from the reservoir contained in the bones) in children and adolescents ranging from 6 to 18 years of age.

A significant effect on increasing serum retinol concentration and hemoglobin levels was shown in trials investigating the fortification of flour with vitamin A in children, 1 to 16 years of age.

Iodine fortification of salt showed a significant effect in elevating urinary iodine concentrations whereas the effect on serum thyroxin levels was non-significant.

Effects of food fortification in women

Iron fortification was associated with a significant increase of hemoglobin and ferritin levels for healthy and iron-deficient women; whereas, the impact on anemia was only significant for the iron-deficient population.

The fortification of flour with folic acid (vitamin B9) – at doses of at least 40 micrograms folate per 100 grams flour – significantly reduced the prevalence of neural tube defects (incl. spina bifida and anencephaly) after (at least) 1 year of intervention. The impacts were non-significant for red blood cell folate levels or serum folate concentration.

Iodine fortification of salt resulted in significant increases of urinary iodine concentration and a reduction of the incidence of hypothyroidism. The effect was non-significant on serum thyroxin levels.

An analysis of randomized controlled trials investigating health impacts of vitamin D and calcium showed significant increases of serum concentration of 25-hydroxyvitamin D3 and decreases of parathyroid hormone concentration in post-menopausal women. Results also indicated a significant impact on reducing the serum levels of bone resorption markers (known to indicate an elevated risk of osteoporosis) in women of repro-ductive age and post-menopausal women.

Fortification alone, though promising, is not an answer to the widespread global nutritional deficiencies. With burdens of diarrhea and enteropathy, widespread malabsorption may be a barrier to this strategy’s maximal effectiveness. Integration of fortification and supplementation strategies together with other mother-and-child health and prevention programs may be the answer to address the widespread global under-nutrition and to ensure sustainable benefits. Community education and promotion campaigns should also be implemented parallel to the primary fortification programs to increase awareness, acceptability and equity. Future forti-fication programs also need to assess the direct impact of fortification on morbidity and mortality.”

Based on: Das J. K. et al. Micronutrient fortification of food and its impact on woman and child health: a systematic review. Systematic Reviews. 2013; 2:67.

References

1. Allen L. D. et al. Guidelines on food fortification with micronutrients. Geneva: World Health Organization/Food and Agriculture Organization; 2006.

2. Serdula M. The opportunity of flour fortification: building on the evidence to move forward. Food Nutr Bull. 2010; 31(1 Suppl):S3.