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Nutrition and Health (including climate and ecological aspects)

A proposed method for defining the required fortification level of micronutrients in foods: An example using iron


In 2006, the WHO published a framework for calculating the desired level of fortification of any micronutrient in any staple food vehicle, to reduce micronutrient malnutrition. This framework set the target median nutrient intake, of the population consuming the fortified food, at the 97.5th percentile of their nutrient requirement distribution; the Probability of Inadequacy (PIA) of the nutrient would then be 2.5%. We argue here that the targeted median nutrient intake should be at Estimated Average Requirement (50th percentile), since the intake distribution will then overlap the requirement distribution in a population that is in homeostasis, resulting in a PIA of 50%. It is also important to recognize that setting the target PIA at 2.5% may put a sizable proportion at risk of adverse consequences associated with exceeding the tolerable upper limit (TUL) of intake. This is a critical departure from the WHO framework. For a population with different age- and sex-groups, the pragmatic way to fix the fortification level for a staple food vehicle is by achieving a target PIA of 50% in the most deprived age- or sex-group of that population, subject to the condition that only a very small proportion of intakes exceed the TUL. The methods described here will aid precision in public health nutrition, to pragmatically determine the precise fortification level of a nutrient in a food vehicle, while balancing risks of inadequacy and excess intake.

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Fig. 1: Symmetric nutrient intake and requirement distributions.
Fig. 2: The risk of inadequate nutrient intake over its requirement and habitual intake for a hypothetical population with zero gap between individual requirements and intakes.
Fig. 3: An example of the calculation of iron fortification levels in cereal, using a randomly selected dataset from Indian National Nutrition Monitoring Bureau (2012) survey.
Fig. 4: Additional iron intake required (8) to achieve a PIA.

Data availability

This was a secondary data analysis, based on a dummy dataset generated out of original data from the National Nutrition Monitoring Bureau (NNMB) 2012. The NNMB data are the property of the Indian Council of Medical Research - National Institute of Nutrition, Hyderabad, India.


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HSS, TT and AVK are recipients of the Wellcome Trust/Department of Biotechnology India Alliance Clinical/Public Health Research Centre Grant # IA/CRC/19/1/610006.

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Authors and Affiliations



SG, HSS and AVK conceived the idea, SG and TT conducted all statistical analyses; all authors guided the analyses and were involved during drafting and approval of the final manuscript.

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Correspondence to Harshpal S. Sachdev or Anura V. Kurpad.

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Competing interests

HSS is a member of the World Health Organization Nutrition Guidance Expert Advisory Subgroup on Diet and Health. HSS and AVK are members of Expert Groups of the Ministry of Health and Family Welfare on Nutrition and Child Health, the National Technical Board on Nutrition of the Niti Aayog, Government of India and the Food Standards and Safety Authority of India. KMN is the Chairperson of the FSSAI Scientific Panel on Labelling, Claims and Advertisements, and a member of FSSAI Expert Committee 2 for Approval of Non-specified Food and Food Ingredients and a member of the FSSAI Scientific Panel on Nutrition and Fortification.

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Ghosh, S., Thomas, T., Pullakhandam, R. et al. A proposed method for defining the required fortification level of micronutrients in foods: An example using iron. Eur J Clin Nutr (2022).

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