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If nutrition had a World Series, iron would never make the playoffs. Vitamin A scores home runs for preventing childhood blindness. Folic acid knocks it out of the park by preventing devastating birth defects. Iodine throws a shut-out by protecting a child’s IQ.
On the other hand, iron gives people energy and protects a child’s cognitive capacity with very little fanfare. When iron deficiency is severe enough, people can develop anemia. With anemia, there are insufficient red blood cells to carry oxygen from the lungs to the rest of the body. Any woman who has had anemia from iron deficiency will tell you it causes debilitating fatigue. But fatigue is hard to picture, and it can be difficult to raise funds and recruit public health leaders to defeat an invisible problem.
Another reason iron doesn’t make the big leagues is that people think iron deficiency is a problem only in developing countries. Yet the World Health Organization (WHO) says iron deficiency is the “most common and widespread nutritional disorder in the world… It is the only nutrient deficiency which is also significantly prevalent in Industrialized Countries.” For example, the United Kingdom’s latest National Diet and Nutrition Survey shows low iron intakes among 23% of women aged 19 to 64 years and 46% of girls aged 11 to 18 years.
The magnitude of the global problem can be overwhelming. The WHO’s Global Prevalence of Anemia in 2011 estimates that 243.2 million nonpregnant women of child-bearing age and 16.2 million pregnant women have anemia related to iron deficiency.
And those figures do not include the estimated 114.7 million children who have anemia from iron deficiency worldwide. Men are less likely than women to have iron deficiency, so they’re not typically included in anemia surveys.
How do you go to bat against a health concern that is globally pervasive yet generally invisible? One solution is to add iron to commonly consumed foods. Flour has been iron-fortified in some countries for decades, yet most of these programs have not been evaluated. That’s like fielding a team of professional players but not keeping score.
To address this, my colleagues and I at the Food Fortification Initiative began looking at anemia prevalence in nonpregnant women. We found anemia reports in national surveys, such as the Demographic and Health Surveys, Multiple Indicator Cluster Surveys, and Vitamin and Mineral Nutrition Information System from the WHO. In countries with fortification programs, we compared anemia before and after fortification began; in countries without fortification, we compared anemia from two different surveys as a kind of control group for our analysis.
We looked for countries that fortified wheat flour alone or in combination with maize flour. Fortification had to include at least iron, folic acid, vitamin A or vitamin B12 since deficiencies in any of these nutrients can cause anemia. We included countries in our study if they had anemia data from before and after fortification began. Twelve “fortification countries” met this criterion. For comparison, we found 20 countries with at least two national surveys on anemia but no flour fortification program.
Iron deficiency is the single most common cause of anemia, but not the only cause. To account for other variables that affect anemia prevalence, we factored in a country’s social and economic development (as captured by the Human Development Index) and whether malaria was endemic. We concluded that in the 12 “fortification countries,” each year of fortification was associated with a 2.4% decline in anemia prevalence. In comparison, the nonfortification countries had a 0.1% decline in anemia prevalence over time.
After this study was published in the British Journal of Nutrition earlier this year, Richard Hurrell, professor emeritus for human nutrition, ETH Zurich, made an important observation in response. In an invited commentary, he noted that most of the 12 “fortification countries” used iron compounds recommended by the WHO.
Iron compounds vary greatly in their bioavailability; that’s the extent to which they can be absorbed by the human body. Using a nonbioavailable compound, or using inadequate amounts of a recommended iron compound, will prevent fortification from having a significant impact on iron deficiency anemia.
People don’t need to worry about getting too much iron from fortification, even when a highly bioavailable form is used. The human body is designed to absorb the iron it needs and discard the rest. Only people with diseases associated with iron absorption have to manage their iron intake to avoid excess levels.
In a second project, I worked with colleagues at the Global Alliance for Improved Nutrition (GAIN) and the US Centers for Disease Control and Prevention’s International Micronutrient Malnutrition Prevention and Control (IMMPaCt) program. We conducted the first systematic review of the effectiveness of flour fortification on iron and anemia outcomes.
We used in-depth evaluations (published and unpublished) of national and subnational programs that fortify flour with iron. The reviewed reports all compared data collected before fortification with data collected at least 12 months after fortification began. We didn’t include studies without both a pre- and post-fortification evaluation. Fortification was for wheat flour alone or in combination with maize flour.
Our review, just published in Nutrition Reviews, showed that fortification consistently improved the iron status of women. But we found limited evidence for fortification reducing the prevalence of anemia. A key point is that the type of iron used followed WHO recommendations in eight of the 13 studies reviewed. But only two of the studies added the minimum recommended level of iron. Women were getting more iron than they would have without fortification, but evidently it wasn’t enough to boost them out of anemia.
For a grand slam in nutrition, any food fortification program needs to reach the majority of the population and be monitored to ensure quality and impact. To get a hit against iron deficiency anemia, fortifying with iron must also meet these two basic requirements: use a bioavailable form of iron and use it at recommended concentrations.