We previously identified 7 low/lower-middle income countries (LMICs; Afghanistan, Pakistan, India, Mongolia, Yemen, Nigeria, Tunisia) which have excess burden of vitamin D deficiency and could benefit enormously from food fortification with vitamin D. A key challenge is finding a suitable industrially-manufactured food vehicle that is consumed in sufficient amounts by the population at-risk. We used FAO Food Balance Sheet data (from 2003-2013) to model the potential impact of four different food vehicles (edible plant-based oil, wheat flour, maize flour, and milk), and at different addition levels, on the average per capita vitamin D supply in all 7 LMICs. Daily per capita supply for ˜۹۵ foods was calculated and vitamin D supply determined using dietary analysis software with no addition and following stepwise additions of vitamin D to the four food vehicles. The daily per capita vitamin D supply without fortification ranged from 0.4 to 3.3 μg (≤۲ μg/d in six LMICs). We applied a vitamin D intake of 5 μg/d as a benchmark because it maintains serum 25-hydroxyvitamin D ≥ ۲۵ nmol/L in ˜۹۰% of individuals. Modelling showed that fortifying edible oil with vitamin D at the 7.5 μg/100 g (guideline) and 15 μg/100 g levels allowed vitamin D supply in 1 and 3 of the 7 LMICs, respectively, to attain ≥۵ μg/d (range: 5.8–۱۱٫۰ μg/d). Fortifying milk at the 1.0 μg/100 g and 2.0 μg/100 g guideline levels, allowed 2 and 3 LMICs, respectively, to attain ≥۵ μg/d (range: 5.2–۹٫۸ μg/d). Fortifying wheat flour at the 1.4 μg/100 g (guideline) and 2.8 μg/100 g allowed 5 and 6 LMICs, respectively, to attain ≥۵ μg/d (range: 5.3–۱۸٫۶ μg/d). Maize flour had low impact due to consumption levels. In conclusion, using these levels of addition, at least one food vehicle was able to increase per capita vitamin D supply to ≥۵ μg/d in each of the LMICs.
While there has been considerable and on-going emphasis placed on the issue of vitamin D deficiency in the higher income country setting, in recent years there has been growing concern about vitamin D deficiency as a possible public health concern in low- and lower-middle income countries (LMICs). Several systematic literature reviews (SLRs) of global vitamin D status [1,2], as well as our recent LMIC-focussed SLR , highlight the general lack of available data on prevalence of vitamin D status for the majority of LMICs. It is of note, however, that where such data does exist, several LMICs have been consistently shown to have extremely high and worrisome estimates of the prevalence of low vitamin D status [1–۳], potentially putting the health and wellbeing of significant numbers of individuals within these populations at risk. These reported prevalence estimates in many cases far exceed the suggested guide of where more than 20% of the population (overall, or within identifiable subgroups) has circulating 25-hydroxyvitamin D (25(OH)D) concentrations < 25/30 nmol/L, public health intervention should be considered . Of particular concern, within the LMICs, infants, young children and women of child-bearing age were shown to be at highest risk [2,3], subgroups of the population which the World Health Organisation (WHO) emphasise in terms of ensuring adequate nutrition [5,6].
In terms of public health interventions that could be considered to address the excess prevalence of vitamin D deficiency in these LMICs, the World Health Organisation-Food and Agriculture Organization (WHO-FAO) have indicated that of the four key strategies for the control of micronutrient malnutrition, food fortification is the preferred approach in terms of sustainability, uptake and cost-effectiveness . The Global Fortification Data Exchange has recently suggested that twothirds of all countries mandate food fortification to combat micronutrient malnutrition, yet many are not necessarily translating policy into improved nutrition . They suggest food fortification could be the next global health success story – if countries close the gaps . Thus, food fortification with vitamin D could have enormous impact in the atrisk LMICs, once done effectively. The WHO-FAO stress that a key challenge is finding a suitable, culturally appropriate, industriallymanufactured food vehicle that is consumed in sufficient amounts by the populations at-risk . Black et al.  have also suggested that beyond the range of food vehicles used for fortification, careful consideration must also be given to the concentration of vitamin D used in each to optimize the effectiveness and minimize risk of excessive intakes. While this can be achieved by modelling usual food consumption intakes in representative populations [7,9], there is a dearth of intake data in LMICs [3,4]. In the absence of such data, we have recently shown that estimates of average per capita supply of vitamin D in LMICs, as calculated using information from FAO Food Balance Sheets (FBS), may be of use as proxy measures for vitamin D intake within the population .