Effectiveness and Potential Toxicity of Bread Fortification With Vitamin D in General Population: A Predictive Modeling Study

Abstract

Background: Vitamin D fortification of bakery's wheat flour, which excludes flours used for confectionaries and bulky breads, can be a suitable strategy to improve vitamin D status of the general population.

Objectives: This study aimed to generate a predictive model to anticipate the effectiveness and potential risk of vitamin D-fortified bread in different fortification doses in general population.

Methods: To gather baseline data before implementation of flour fortification, a cross-sectional descriptive study was conducted on a representative sample comprising 1051 subjects aged 7-65 y from 2 cities Birjand and Yazd. Demographic, anthropometric, and laboratory assessments were performed for all subjects. The amount of bread consumption was estimated using a 24-h recall questionnaire. A simulation model was used to examine the impact of various fortification doses of vitamin D in bread on the proportion of both adults and children achieving sufficient circulating 25-hydroxycalciferol [25(OH)D] concentrations (>50 nmol/L) and potential harm thresholds (>375 nmol/L). The baseline serum 25(OH)D concentration data were used as a reference for comparison at each fortification dose. Circulating 25(OH)D between 27.5 and 50 nmol/L and below 27.5 nmol/L was considered as insufficiency and deficiency, respectively.

Results: Substantial proportions of both children and adults fell into the insufficient (37.5% and 37.4%, respectively) and deficient (34.7% and 31.8%, respectively) categories. Our model showed that the fortification dose of 250 IU/100g bread could be an effective strategy for significantly improving vitamin D status in the general population. Higher doses, such as 500 IU/100g, results in >70% of the population achieving sufficient 25(OH)D concentrations. However, starting at 400 IU/100 g bread, a very small percentage (0.1%) of the population could reach potentially harmful concentrations.

Conclusions: By adding 250-350 IU vitamin D per 100 g bread, over half of the general population can reach to sufficient vitamin D status with no potential risk of toxicity.

Keywords: 25(OH)D; bread; food fortification; modeling; vitamin D.