A New Approach to Estimate Safe Maximum Fortification Levels for Micronutrients

Abstract

Objectives: Maximum fortification levels for voluntarily fortified foods are meant to guard against excessive micronutrient intake. Existing methods of estimating safe maximum levels take a conservative approach by considering a single point in the intake distribution of the micronutrient of interest. The free space for fortification has traditionally been estimated as the tolerable upper intake level minus an observed high intake value (e.g., 95th percentile), with or without considering the contribution of supplements. Using a single value from the distribution results in a single estimate of a safe maximum fortification level. This potentially results in unrealistically high estimates. We propose a probabilistic approach for setting safe maximum fortification levels. Methods: We build upon the estimation of i) a measure of the amount of the food supply that is potentially fortifiable with a micronutrient (i.e., the ‘fortifiable pool'), and ii) a ‘free space' available for intake from voluntarily fortified sources. As a proxy for the fortifiable pool, we utilize the fraction of energy provided by potentially fortifiable foods. The energy from the fortifiable pool and nutrient intake from food and supplemental sources are then jointly modeled. Results: Applying this probabilistic approach to the estimation of safe maximum fortification levels provides a distribution of safe maximum fortification levels from which an appropriate level can be chosen. Conclusions: This approach can estimate safe maximum fortification levels that more realistically convey the potential benefits to be achieved by increased micronutrient intake through voluntary fortified foods, as well as the risks associated with excessive intake.