Double-Salt Fortification

Supplement in The Journal of Nutrition explores whether fortification of salt with iodine and iron could solve a major global health problem.

Published as a supplement in The Journal of Nutrition, The State of Evidence and Experiences in Double Fortified Salt (iodized salt with iron, presents the latest evidence to “help advise policy makers considering double-fortified salt as an intervention to address the difficult public health issue of iron deficiency anemia as well as iodine anemia.”

Iron deficiency remains one of the most severe and important nutritional deficiencies in the world.

The World Health Organization (WHO) has stated that “iron deficiency, and specifically iron deficiency anemia, remains one of the most severe and important nutritional deficiencies in the world today.”  Among the negative health outcomes associated with iron deficiency and anemia are poor fetal and child brain development, poor child cognitive function, poor iodine utilization, poor pregnancy outcomes, and higher infant mortality.  Women, children, and female adolescents in low- and middle-income countries, in particular, are at greatest risk for iron deficiency and resulting anemia.

In contrast to iron deficiency and iron deficiency anemia, which remain an urgent global public health challenge, the problem of iodine deficiency has largely been alleviated with the advent of iodine fortified salt, beginning in the 1920s.  “As a result,” according to Richard Hurrell, author of the supplement’s introductory paper, “goiter, cretinism, and severe iodine deficiency have been eradicated from many countries.”

Could the additional fortification of iodized salt with iron be as effective in eradicating iron deficiency and iron deficiency anemia?

Iodine fortified salt has been particularly successful because salt is universally consumed in predictable amounts by all population groups around the world.  The question is could the additional fortification of iodized salt with iron be as effective in eradicating iron deficiency and iron deficiency anemia?  Dr. Hurrell believes it “has the potential to be the universal global carrier for both iodine and iron provided that the technical challenges for the iron fortification of salt can be overcome.”

The five scientific review papers in the supplement explore both the potential and the challenges of double-fortified salt:

• ASN member Denish Moorthy et al. assessed the challenges and opportunities that have been encountered by double-fortified salt programs in India, Argentina, Cote d’Ivoire, Kenya, Morocco, Nigeria, Philippines, and Sri Lanka.  They concluded that double-fortified salt “offers a unique opportunity to leverage an almost universally consumed product.”  Challenges, however, such as a lack of consumer acceptance and government backing, must be overcome.
• ASN member Richard Hurrell reviewed the potential of double-fortified salt to improve population iron status compared to fortified wheat flour, maize flour, rice, and milk. Because wheat flour fortification production and practices are the most advanced, he concluded that “in populations where there is adequate consumption of industrially milled wheat flour, wheat flour is technologically preferable for iron fortification.”  In other populations, where milled flour is not regularly consumed, double-fortified salt has demonstrated potential for iron fortification.  Dr. Hurrell did point out that technical issues remain.  Furthermore, “studies are needed to better understand and avoid color formation and iron-catalysed iodine losses in both high- and low-quality salts under different storage conditions.”
• ASN member Leila Larson et al. reviewed randomized efficacy studies as well as two effectiveness evaluations of double-fortified salt programs.  Their findings demonstrate “the potential for double-fortified salts to improve iron status across several population groups.”  The authors, however, cautioned that double-fortified salt programs, in order to be successful, will need to create demand among populations with iron deficiency by considering local preferences, traditions, and needs.
• ASN member Alister Shields et al. reported on the technical and financial challenges faced by manufacturers of double-fortified salt.  Due to manufacturing costs, the authors believe “double-fortified salt can only have potential as a premium product that targets higher-income consumers.  Such a product is likely to have a limited impact on the prevalence of iron-deficiency anemia, which is closely associated with socio-economic status.”

Much work is needed for double-fortified salt to have a positive impact on global iron deficiency.

• The Double-Fortified Salt Steering Group, a multi-sector collaboration of salt and public health experts created under the aegis of the Iodine Global Network, summarized the findings and considerations published in this supplement.  By bringing together and analyzing the evidence and real-world experience in double-salt fortification, the Steering Group has underscored the issues that program managers and decision makers should explore when considering the development and implementation of a double-fortified salt program.  Much work is needed for double-fortified salt to have a positive impact on global iron deficiency, according to the Steering Group, including the development of international quality standards and additional research to identify effective iron fortification formulations.

In their preface to the supplement, the Steering Group noted, “it is the hope of the Steering Group that this supplement will provide a comprehensive evidence base that can help policy makers in countries considering initiating double-fortified salt, so that they may make informed decisions for their national nutrition strategy.”

We invite you to explore The State of Evidence and Experiences in Double Fortified Salt (iodized salt with iron in full.