Micronutrient‐fortified bouillon as a strategy to improve the micronutrient adequacy of diets in Burkina Faso

Bouillon is a promising candidate for fortification to complement existing large‐scale food fortification (LSFF) programs. We used household dietary data from Burkina Faso to model potential contributions of bouillon fortified with vitamin A (40–250 μg/g bouillon), folic acid (20–120 μg/g), vitamin B12 (0.2–2 μg/g), iron (0.6–5 mg/g), and zinc (0.6–5 mg/g) for meeting micronutrient requirements of women of reproductive age (15–49 years; WRA) and children (6–59 months). Most households (82%) reported bouillon consumption, with higher proportions of resource‐constrained (84–88%) and rural households (88%) consuming bouillon. Accounting for the contributions of existing LSFF, household diets were inadequate to meet the micronutrient requirements of many WRA and children, exceeding 90% and 60% inadequacy for vitamins A and B12, respectively. Modeling results showed bouillon fortification could reduce inadequacy by up to ∼30 percentage points (pp) for vitamin A, ∼26 pp for folate among WRA (∼11 pp among children), ∼38 pp for vitamin B12, and 11–13 pp for zinc, with comparable reductions across socioeconomic strata and urban and rural residence. Predicted reductions in iron inadequacy were <3 pp. These results suggest dietary micronutrient inadequacies are a concern in Burkina Faso, and fortified bouillon can make substantial contributions to reducing micronutrient inadequacies, including among resource‐constrained and rural populations.

serum folate ≤13.4 nmol/L, and 12% have vitamin B12 <203.0 pg/mL. 5ile results from the National Micronutrient Survey for WRA are still pending, over half of WRA in Burkina Faso are anemic according to the 2021 Demographic and Health Survey. 6eally, interventions aimed at increasing both the supply of and demand for diverse, micronutrient-dense foods would drive sustainable improvements in the micronutrient adequacy of diets and, ultimately, help reduce the burden of micronutrient deficiencies.Given the challenges associated with changing food systems and bringing about prescriptive changes in dietary habits, food fortification can play an important role in improving dietary quality. 2 Food fortification involves the addition of one or more micronutrients to processed foods or condiments. 2 The success of food fortification programs depends on the identification of a food vehicle or sets of food vehicles that are consumed in fortifiable form (i.e., industrially processed) and in sufficient quantities by populations at greatest risk of deficiencies.Success also rests upon strong systems for regulatory monitoring and enforcement to ensure industry compliance with national fortification standards.
[9] Bouillon, a condiment added to dishes during cooking as a seasoning, may be a promising candidate for fortification to complement existing large-scale food fortification (LSFF) programs in some countries. 10,11 some regions of the world, including many countries in West Africa, bouillon is regularly consumed in consistent quantities by large segments of the population, including populations experiencing poverty and rural populations who may be less likely to consume fortifiable forms of other commonly fortified food vehicles. 10Also, compared to other food vehicles, the concentration of bouillon production among a small number of large companies may allow for easier regulatory monitoring and enforcement of standards. 2ile bouillon is voluntarily fortified with iron or vitamin A in some countries, 10 there is limited evidence on the efficacy of fortified bouillon for improving micronutrient status or other nutritional outcomes. 12To fill this gap, a randomized controlled trial is currently underway in Northern Ghana to assess the efficacy of bouillon fortified with vitamin A, folic acid, vitamin B12, iron, and zinc. 13,14Other information is needed to inform discussions on bouillon fortification standards, including information on technical aspects of fortification and potential program costs.As part of a broader initiative to build the evidence base for bouillon fortification, in this paper, we provide complementary, modeling-based evidence using household food consumption data on the potential contribution of multiple micronutrientfortified bouillon to meeting micronutrient requirements in Burkina Faso.Our modeling focused on women of reproductive age (15-49   years; WRA) and young children (6-59 months), population groups with high relative micronutrient requirements, making them particularly vulnerable to micronutrient deficiencies. 1,2We modeled potential contributions of multiple micronutrient-fortified bouillon over a range of potential fortification levels at the national level, and, to consider potential impacts among traditionally harder-to-reach populations, we also modeled the potential contributions of fortified bouillon by household socioeconomic status (SES) as well as urban and rural residence.Alongside these estimates of potential nutrition benefits, for micronutrients with tolerable upper intake levels, we also assessed the potential risk of high intakes with bouillon fortification.Our findings provide policymakers and their advisors in Burkina Faso with evidence on current dietary micronutrient inadequacies and the potential for fortified bouillon to help close dietary micronutrient gaps.

Apparent food consumption and nutrient intake
We used household dietary data from the most recent household consumption and expenditure survey conducted in Burkina Faso, the 2018-2019 Enquête Harmonisée sur les Conditions de Vie des Ménages (EHCVM) to estimate apparent food consumption and nutrient intake.The EHCVM was implemented by the National Institute of Statistics and Demography (INSD) in Burkina Faso, with support from the World Bank and the West Africa Economic Monetary Union Commission.The survey was representative at the national, urban, and rural levels, and to capture seasonality in consumption, data were collected in two waves, from October to December of 2018 and April to July of 2019. 15We requested and received approval from INSD to use the deidentified 2018-2019 EHCVM data for these analyses.The data were used in compliance with INSD's data access policy.
To estimate apparent household food consumption, we used data from the EHCVM food consumption and acquisition module in which the household respondent was asked to recall the quantity of each of 138 food items consumed by household members in the 7 days before the survey.Respondents were also asked to recall the source of foods consumed, including purchased, own production, gifts, and so on.Where applicable, we adjusted the total quantity of food apparently consumed by the household for the edible portion and yield factor from cooking.We did not make adjustments for food waste or loss.We adjusted for extreme outliers in reported quantities of food consumed by identifying the food-and region-specific 95th percentile of apparent household consumption per adult male equivalent (AME) and replacing quantities above the 95th percentile with the value at the 95th percentile.
We estimated the nutrient composition of each food item in the EHCVM food list by matching the food to a food composition table (FCT) entry, or to a weighted average of several FCT entries for aggregate or generic food items.For example, the nutrient composition of the food item "meat of other domestic poultry" was based on a weighted average of guinea fowl, turkey, and duck.Food items were primarily matched with entries from the West African FCT, 16 and when appropriate matches from the West African FCT were not available, we used nutrient composition estimates from the Nutrition Coordinating Center Nutrient Database for Standard Reference 17 and the Malawian FCT. 18utrient density, or the quantity of a nutrient per quantity of food or beverage, is a measure of the quality of the diet. 19For vitamin A, folic acid, vitamin B12, iron, and zinc, we calculated the apparent nutrient density of the household diet as the ratio of total daily household apparent intake of the micronutrient to total daily household energy intake, expressed per 1000 kilocalories (kcal) by multiplying that ratio by 1000.We assessed the adequacy of the household diet for meeting the micronutrient requirements of target household members (WRA and children 6-59 months of age) by comparing the nutrient density of the household diet to the critical nutrient density of target household members.Critical nutrient densities were calculated as the age-and sex-specific estimated average requirement (EAR) (or values along the distribution of requirements for iron) divided by the age-and sex-specific energy requirements of the target household member, expressed per 1000 kcals.Micronutrient requirements were from the US Institute of Medicine 20,21 for all nutrients except zinc.
Based on dietary patterns in Burkina Faso, we assumed a 10% bioavailability of iron from all sources except fortified bouillon (detailed below) and set iron requirements accordingly. 2Using published algorithms for children 22 and adults 23 to estimate absorbable zinc, for each target household member, we calculated fractional zinc absorption as the ratio of absorbed zinc to total zinc.Then, we estimated dietary zinc requirements (and critical nutrient densities) by adjusting physiological zinc requirements for children 24 and WRA 25 by the estimated person-specific fractional zinc absorption.Energy requirements were estimated relative to the Food and Agricultural Organization (FAO) human energy requirement estimate of 2900 kcals for a 65kg adult male age 18-30 years with moderate physical activity. 26See Table S1 for assumed micronutrient and energy requirements.
For all micronutrients except iron, we assessed the apparent adequacy of the household diet for meeting the micronutrient requirements of WRA and children by comparing the nutrient density of the household diet to the target household member's critical nutrient density using the EAR cut-point method.Because iron requirements are not normally distributed for some population groups, we assessed the adequacy of the iron density of the household diet for meeting the iron requirements of children and nonpregnant WRA using the full probability approach. 2Apparent risk of high intake of vitamin A (in the form of preformed retinol), folic acid, iron, and zinc were estimated by comparing the nutrient density of the household diet to the critical upper density of target household members, defined as the age-and sex-specific tolerable upper intake level (UL) divided by the age-and sex-specific energy requirement, expressed per 1000 kcals (see Table S2 for assumed ULs).
As nutrient density is a metric of dietary quality, classifications of dietary adequacy and high intakes were based on the assumption that household members were meeting their age-and sex-specific energy requirements. 27Because we used dietary data collected at the household level, meeting the micronutrient requirements of specific household members also assumes food was distributed within the household according to each household member's age-and sex-specific energy requirements.To emphasize these and other assumptions inherent in using household-level data to assess dietary micronutri-ent adequacy and risk of high intakes, estimates are qualified with "apparent." Target household members (WRA and children 6-59 months of age) were identified in the EHCVM data using the household roster.
If a household had more than one member in a target group, we randomly selected one household member to include in analyses of that target group.Similarly, if a household did not have a member in a target group, that household was not included in analyses of that target group.Micronutrient adequacy was assessed separately for pregnant and nonpregnant women by estimating the prevalence of inadequacy assuming all WRA in the sample were pregnant and then assuming all WRA were nonpregnant.These separate prevalence estimates were then combined into an overall estimate of micronutrient inadequacy among WRA as a weighted average of the two estimates, where weights were based on estimates of the proportion of WRA current pregnant and not pregnant according to the 2021 Demographic and Health Survey. 6

Modeling the contribution of LSFF
We used the AME method to estimate apparent consumption of refined oil, wheat flour, and bouillon, which assumes food is distributed within the household in proportion to each member's age-and sexspecific energy requirements. 28Specifically, based on the demographic composition of each household, we assigned an AME weight to each household member, calculated as the ratio of the household member's energy requirements to the energy requirements of a male age 18-30 years. 26We then calculated an AME ratio for target household members as the individual's AME weight divided by the total number of AMEs in the household.Individual apparent consumption of each food vehicle was then calculated as total household apparent consumption multiplied by the individual's AME weight.Estimates of apparent consumption of refined oil included specific items on the food list (soybean oil, cottonseed oil, and "other" oils, which we assumed was primarily refined vegetable oil) as well as processed food items containing refined oil (e.g., refined oil in cakes); consumption of refined oil in processed foods was based on the assumed proportion of refined oil in the processed food.Note that red palm oil was a separate item in the food list and was not included in estimates of apparent refined oil consumption.Similarly, estimates of apparent wheat flour consumption included consumption reported as "wheat flour" in the food list as well as contributions from processed foods containing wheat flour, such as bread.
Burkina Faso currently mandates the fortification of refined oil with vitamin A (17.5 mg/kg) and wheat flour with iron (60 mg/kg) and folic acid (2.5 mg/kg) 29 (Table S2).We calculated average current fortification levels by adjusting the mandated fortification levels for the percent of the food vehicle that is fortifiable as well as the most recent evidence on the proportion of the food vehicle that is fortified to any extent and the average fortification level (Table 1, primary analysis).
We modeled the contribution of current nationally mandated fortification to meeting micronutrient requirements by multiplying the daily  to account for the possibility that not all bouillon would be fortified, we assumed 75% of bouillon would be fortified to the specified level and adjusted the modeled fortification level accordingly (i.e., we multiplied each fortification level by 0.75 to arrive at an average fortification level if 75% of bouillon were fortified).Then, we multiplied daily apparent bouillon consumption by each adjusted fortification level and recalculated the nutrient density of the household diet and prevalence of inadequacy in the presence of both existing LSFF and bouillon fortification.We assumed that, without the coaddition of compounds to enhance iron absorption, 2% of iron from fortified bouillon would be absorbed. 30,31At each potential bouillon fortification level, we also assessed the risk of high intakes by comparing the nutrient density of the household diet to the critical upper densities of target household members (Table S2).
We did not model the contribution of supplementation or voluntary fortification, as the EHCVM survey did not collect data on the consumption of micronutrient supplements, and there is insufficient data on the extent of voluntary fortification and levels of micronutrients voluntarily added to some food products in Burkina Faso.Also, because breastfeeding status was not collected in the EHCVM survey, we did not account for the contribution of breastmilk to meeting the micronutrient requirements of young children, and modeling reflects the adequacy of diets without breastmilk.Quintiles of household SES were constructed based on annual per capita household expenditures as reported in the EHCVM data.All comparisons across food vehicles and population subgroups of apparent consumption of potentially fortifiable foods and the prevalence of micronutrient inadequacy were qualitative.

Regional estimates and sensitivity analysis
Our primary modeling scenarios assessed the potential contribution of fortified bouillon across a range of potential bouillon fortification levels for meeting the needs of WRA and young children at the national level, by household SES, and by urban and rural residence.In addition, to explore the potential contribution of fortified bouillon in each of Burkina Faso's 13 regions, for each micronutrient, we modeled an additional scenario in which the modeled fortification level was selected based on meeting 30% of the Codex nutrient reference value (NRV), calculated assuming 2.5 grams of bouillon consumption per day among adults (per gram bouillon: 96 µg vitamin A, 28.8 µg folic acid, 0.288 µg vitamin B12, 2.64 mg iron, and 1.68 mg zinc) (Table S3).These fortification levels may be commercially feasible for voluntary fortification and would meet Codex requirements for claiming "high in" on labels because they provide at least 30% of Codex NRVs in an assumed serving size of 2.5 grams per day.As before, these fortification levels were adjusted for the assumption that 75% of the bouillon would be fortified to these levels.
The potential contributions of fortified bouillon to meeting micronutrient requirements were modeled based on the most recent data available on average current fortification levels of refined oil and wheat flour in Burkina Faso, both of which are substantially below the mandated fortification levels (Table 1, primary analysis).As a sensitivity analysis, we also estimated the prevalence of inadequacy and risk of high intakes with bouillon fortification if compliance with the national refined oil and wheat flour standards improved (Table 1, sensitivity analysis).

Apparent consumption of fortifiable foods and condiments
Nationally, 75% of households reported consuming purchased refined oil (or products containing refined oil) in the 7 days preceding the survey, varying from 64% to 87% among households in the lowest and highest quintiles of SES, respectively, and reported consumption was higher among urban household (86%) than rural households (72%) (Table 2).Among households that reported consumption of refined oil, median apparent consumption was 11.3 grams per day for WRA and  2, Table S6, and Figure S2).For vitamin B12, the prevalence of inadequacy by SES among WRA ranged from 38% in the highest SES to 84% in the lowest SES, while inadequacy among rural households was more than 30 percentage points higher than among urban households (Figure 3, Table S8, and Figure S3).Finally, there was a of children in urban households and in households in the highest SES quintile (Figure 1, Table S5, and Figure S1).
Nationally, folate inadequacy among WRA was predicted to drop from 35% with folic acid-fortified wheat flour at current compliance to 8-22% with the addition of bouillon fortified with folic acid, with large reductions in inadequacy at fortification levels up to ∼60-80 µg folic acid/gram bouillon and leveling off thereafter (Figure 2 and Table S6).
At 80 µg/gram bouillon, reductions in folate inadequacy among WRA dropped to below 20% across all quintiles of household SES (Figure 2) and in both urban and rural areas (Figure S2).Even at the highest modeled fortification level (120 µg folic acid/gram bouillon), no WRA were predicted to be at risk of high intakes (Table S7).Among children, folate inadequacy at 80 µg folic acid/gram bouillon dropped to less than 12% across all SES and in both urban and rural areas.At this fortification level or higher, the risk of high folic acid intakes among children reached 1-2% among some subpopulations (children residing in households of higher SES and in urban households).
Currently, there is no national fortification program for vitamin B12 in Burkina Faso.Introducing vitamin B12-fortified bouillon at levels between 0.2 and 2 µg vitamin B12/gram bouillon was predicted to reduce the prevalence of inadequacy among WRA from 66% nationally to 29-62% and from 61% among children to 23-57% (Figure 3 and Table S8).Especially among WRA and children residing in house-holds in the lower quintiles of SES and in rural households, moving from 1.6 to 2 µg vitamin B12 per gram of bouillon continued to make large contributions to reducing vitamin B12 inadequacy (Figure 3 and Figure S3).
The potential contribution of iron-fortified bouillon to reducing iron inadequacy among both WRA and children was limited across all modeled fortification levels, both nationally and across SES and urban and rural areas (Figure 4, Figure S4, and Table S9).Even at the highest modeled fortification level (5 mg iron/gram bouillon), the national prevalence of inadequacy decreased by just 2 percentage points among both children and WRA compared to the status quo situation in which wheat flour is fortified with iron.Even without bouillon fortification, the estimated risk of high iron intakes among WRA from diets plus ironfortified wheat flour was 2% nationally and up to 3-4% among WRA residing in households in the second and third SES quintiles (Figure 4 and Table S10).The risk of high iron intakes among WRA reached 6% nationally at the highest modeled fortification level and up to 11% among WRA in households in the second SES quintile.Iron intakes among children did not exceed the critical upper density in any of the modeled scenarios.
Currently, there is no program in place in Burkina Faso that delivers zinc via LSFF.If bouillon were fortified with zinc, the national prevalence of zinc inadequacy was predicted to drop from 38% to 25-35% F I G U R E 1 Prevalence of apparent vitamin A inadequacy (top) or risk of high intakes (bottom), nationally and by socioeconomic status (SES), with bouillon fortification added to existing fortification (39% of fortifiable refined oil fortified to 85% of the national standard of 17.5 mg/kg) at different bouillon fortification levels.Note that the modeled bouillon fortification levels (x-axis) are not always evenly spaced.SES quintiles are based on annual per capita household expenditures.SES 1 is poorest/lowest quintile of SES; SES 5 is wealthiest/highest quintile of SES.
among WRA and from 44% to 33-41% among children, depending on the fortification level (Figure 5 and Table S11).However, even at the lowest modeled level of zinc fortification (0.6 mg zinc/gram bouillon), 16% of children nationally were at risk of high zinc intakes (up from 10% nationally with baseline diets alone), while 21% of children residing in households in the lowest two SES quintiles and 19% of children in rural areas were at risk of high intakes (Figure 5, Table S11, and Figure S5).The predicted risk of high zinc intakes among WRA was <1% at all modeled fortification levels.

Sensitivity analysis
If compliance with the current national refined oil fortification standard were improved such that 75% of refined oil was fortified to the standard, the national prevalence of vitamin A inadequacy without bouillon fortification was predicted to decrease relative to the current compliance scenario, but the prevalence of inadequacy remained high (86% and 84% inadequacy among WRA and children, respectively; F I G U R E 4 Prevalence of apparent iron inadequacy (top) or risk of high intakes (bottom), nationally and by socioeconomic status (SES), with bouillon fortification added to existing fortification (62% of fortifiable wheat flour fortified to 12% of the national standard of 60 mg/kg) at different bouillon fortification levels.Note that the modeled bouillon fortification levels (x-axis) are not always evenly spaced.SES quintiles are based on annual per capita household expenditures.SES 1 is poorest/lowest quintile of SES; SES 5 is wealthiest/highest quintile of SES.bouillon fortification level "0" in Figures S6 and S7).Across all SES and in both urban and rural areas, the prevalence of inadequacy among both WRA and children remained above 60%.Depending on the fortification level, fortifying bouillon with vitamin A in the presence of refined oil at improved compliance was predicted to reduce the national prevalence of inadequacy to 55-81% among WRA and to 52-79% among children.The risk of high vitamin A intakes among WRA across SES and in urban and rural areas remained below 0.5% at all modeled fortification levels, while the risk of high intakes among children reached 3% in the highest SES quintile at 200 µg/gram bouillon (although nationally, the risk of high intakes remained below 1.5% even at 250 µg/gram bouillon).
Improved compliance with the wheat flour standard (modeled as 75% of wheat flour fortified to the standard) was predicted to bring the national prevalence of folate inadequacy to 27% among WRA and 12% among children (bouillon fortification level "0" in Figures S8 and   S9).Folic acid-fortified bouillon further reduced folate inadequacy to 6-17% among WRA and to 3-8% among children.The risk of high folic acid intakes among WRA remained below 0.5% across all SES and in urban and rural areas except at 120 µg/gram bouillon, where 1% of WRA in the highest SES quintile and 1% of WRA residing in urban areas were at risk of high intakes.Depending on the fortification level, between 1% and 3% of children in the highest SES quintile and in urban areas were at risk of high folic acid intakes.
Compared to current compliance, the prevalence of iron inadequacy among WRA and children dropped only a few percentage points with improved compliance with the wheat flour fortification standard (bouillon fortification level "0" in Figures S10 and S11).Similarly, the additional contribution of iron-fortified bouillon was modest at all modeled fortification levels, while the risk of high iron intakes among WRA exceeded 5% among some subgroups at 1.8 mg/gram bouillon and exceeded 5% nationally at 5 mg/gram bouillon.

DISCUSSION
In the absence of nationally representative 24-hour dietary recall data, modeling of household-level food consumption data can provide policy-relevant evidence on the micronutrient adequacy of diets and potential strategies for filling micronutrient gaps. 32Using household dietary data from Burkina Faso, we found that even with mandatory LSFF standards (fortified refined oil and wheat flour) both under status quo and improved compliance scenarios, household diets were inadequate to meet the micronutrient requirements of many women and children.The predicted prevalence of inadequacy was especially high for vitamin A, which exceeded 90% nationally, and for vitamin B12, which exceeded 60% nationally and was over 80% among some subgroups.Perhaps counterintuitively, we found that, based on the nutrient density of diets, the prevalence of folate and iron inadequacy  Our analysis also showed the potential for risk of high iron intakes among WRA and high zinc intakes among children, although the tolerable upper zinc intake levels for children have recently been criticized as being set below the observed usual dietary zinc intake levels that occur without any apparent adverse effects.If Burkina Faso considered developing voluntary or mandatory bouillon fortification standards, the potential nutrition benefits of bouillon fortification would need to be weighed against the potential risk of high intakes, especially for zinc. 33sed on subnational modeling, we found that bouillon consump- the micronutrient gap between intake and requirements would be too large to be fully met with bouillon fortification at the micronutrient concentrations modeled here.These results suggest that alongside efforts to improve overall diet quality, additional micronutrient intervention strategies (e.g., targeted supplementation) might be needed for some population subgroups.
The results of these analyses should be interpreted with several limitations in mind.First, while we modeled a wide range of poten- Bouillon is composed of approximately 20-30% sodium by weight, 11,36 and given global efforts to reduce sodium intakes, discussions about bouillon fortification consistently include concerns about high sodium intakes and noncommunicable diseases.In addition to research on strategies to reduce sodium content in bouillon, 36 fortification of bouillon can be implemented alongside efforts to promote reductions in sodium intake, as has been discussed elsewhere. 11The World Health Organization recognizes the compatibility of sodium reduction efforts and salt iodization when systems are in place to monitor national intake of sodium/salt as well as iodine, and if and when consumers reduce their salt intake, iodine fortification levels are revised to ensure iodine requirements are still met. 37As with salt, if consumption of bouillon changes in response to sodium reduction campaigns, modeling can be used to revisit and adjust fortification levels as needed to ensure bouillon fortification continues to help fill micronutrient gaps in the diet.
The modeling results presented in this paper suggest that dietary micronutrient inadequacies are a concern in Burkina Faso, and because bouillon is consumed by all segments of the population, multiple micronutrient-fortified bouillon has the potential to make substantial contributions to reducing vitamin A, folate, vitamin B12, and zinc inadequacies, even among traditionally harder-to-reach populations such as households with low SES and in rural areas.There is currently no domestic production of bouillon in Burkina Faso (Vosti et al., in preparation).As such, the establishment of bouillon fortification standards would likely require dialogue and coordination with other countries in the region to establish standards that help meet dietary micronutrient gaps in Burkina Faso while also taking into account the micronutrient situation in other countries in the region that are producing and/or importing fortified bouillon.Another crucial consideration is the potential cost of bouillon fortification programs, which stakeholders might be called upon to pay, and the cost-effectiveness of fortified bouillon.These issues are addressed elsewhere (Vosti et al., in preparation).
Taken together with considerations around technical and commercial feasibility, costs, cost-effectiveness, and strategies for alignment with sodium reduction efforts, the estimates presented in this paper provide important input into the evidence base upon which policy decisions around bouillon fortification in Burkina Faso can be made.The next steps for this research are focused on ensuring that this evidence is appropriately packaged and delivered to policymakers in Burkina Faso.
Replicating the modeling strategy we used here to identify additional micronutrient interventions that may help fill the remaining gaps in micronutrient adequacy would also be valuable.

AUTHOR CONTRIBUTIONS
apparent consumption of each food vehicle by the estimated average current fortification level and then recalculating the nutrient density of the household diet and prevalence of inadequacy.We modeled the potential additional contribution of fortified bouillon (i.e., in addition to current fortification, where relevant) over a range of bouillon fortification levels for each micronutrient (40-250 µg vitamin A per gram bouillon, 20-120 µg folic acid per gram bouillon, 0.2-2 µg vitamin B12 per gram bouillon, 0.6-5 mg iron per gram bouillon, and 0.6-5 mg zinc per gram bouillon).These levels were chosen to represent a wide range of potential micronutrient concentrations in fortified bouillon, allowing for consideration of balancing reductions in micronutrient inadequacy with the risk of high intakes.In the modeling,

Figure 6 (
Figure 6 (WRA), Figure 7 (children), and Tables S13-S17 contain estimates of the prevalence of inadequacy by region in Burkina Faso without bouillon fortification and with bouillon fortified to 30% of the Codex nutrient reference values.With refined oil fortified at current levels of compliance, the prevalence of vitamin A inadequacy among WRA ranged from 80% in the Est Region to 100% in the Sahel Region.With the addition of bouillon fortified at 96 µg vitamin A per gram bouillon, vitamin A inadequacy was reduced to between 70% in the Hauts-Bassins Region and 97% in the Centre-Nord Region.The were higher among WRA and children in households in the upper quintiles of SES compared to those in households of lower SES.This finding is explained by greater consumption of millet and sorghum among households in lower SES quintiles.Given the relatively high folate (millet) and iron (sorghum and millet) density of these staple foods and the high proportion of energy requirements met by these staples among households of low SES, the folate and iron density of these diets were generally better than those of wealthier households.Across a range of potential fortification levels, we found that fortified bouillon had the potential to reduce the national prevalence of vitamin A inadequacy among women and children by up to ∼30 percentage points, folate inadequacy by up to ∼26 percentage points among WRA (up to ∼11 percentage points among children), vitamin B12 by up to ∼38 percentage points, and zinc inadequacy by ∼13 percentage points.Nationally and subnationally, predicted reductions in iron inadequacy were small, estimated to reduce inadequate intake by only 2-3 percentage points at the highest modeled iron fortification levels.In addition, modeling of fortification levels equivalent to 30% Codex NRV in 2.5 grams bouillon per day suggested that this level would have a modest impact for all micronutrients and higher fortification levels would be required to close gaps in micronutrient requirements.One strength of this modeling study was that we examined the potential contribution of a new food vehicle under varying compliance scenarios for foods already subject to mandatory fortification.If com-pliance with Burkina Faso's refined oil fortification standard improved, the marginal contribution of fortified bouillon to reducing the prevalence of vitamin A inadequacy would be slightly higher than under status quo compliance (reducing the prevalence of inadequacy by up to ∼32 percentage points).This is largely due to relatively low quantities of refined oil consumption in Burkina Faso combined with the large gap in the vitamin A density of diets compared to requirements: although increasing the vitamin A delivered by refined oil increases vitamin A density of the diet, the majority of diets remain below requirements; however, this additional amount combined with the vitamin A from fortified bouillon is sufficient to achieve the critical nutrient density for more households.If compliance with the current wheat flour fortification standard improved, the marginal contribution of bouillon fortified with folic acid to reducing folate inadequacy would be slightly smaller than under the status quo situation, although bouillon fortification could still reduce the prevalence of folate inadequacy among WRA by over 20 percentage points.With improved compliance, the marginal contribution of iron-fortified bouillon would be similar to the status quo case.
tion was common not only among better-off households and urban households but also among more resource-constrained households and households residing in rural areas where the consumption of refined oil and wheat flour was less common.Given the ubiquity of bouillon consumption, our modeling showed that, except for iron for which absorption was expected to be low, bouillon fortification had the potential to help meet the micronutrient requirements of WRA and children across socioeconomic strata and residence.However, for some micronutrients and some subgroups, although bouillon fortification would contribute to meeting micronutrient needs, the size of F I G U R E 6 Prevalence of vitamin A, folate, vitamin B12, iron, and zinc inadequacy among women of reproductive age without (left panels) and with (right panels) bouillon fortification modeled to meet 30% of the Codex nutrient reference values, calculated assuming 2.5 g of bouillon consumption per day among adults (per gram bouillon: 96 µg vitamin A, 28.8 µg folic acid, 0.288 µg vitamin B12, 2.64 mg iron, and 1.68 mg zinc).See Tables S13-S17 for point estimates by region.
tial bouillon fortification levels to allow for consideration of balancing reductions in micronutrient inadequacy with the risk of high intakes, micronutrient concentrations selected for bouillon fortification standards would also require research to confirm that they are acceptable to consumers, technically feasible, and commercially viable.Formative research in Northern Ghana demonstrated consumer acceptance of a nonproprietary bouillon formulation fortified with vitamin A, folic acid, vitamin B12, iron, and zinc at concentrations equivalent to 45-125% of Codex nutrient reference values in 2.5 grams of bouillon,34 including the micronutrient concentrations currently being used in the randomized trial in Northern Ghana (200 µg vitamin A, 80 µg folic acid, 1.2 µg vitamin B12, 4 mg iron, and 3 mg zinc per gram of bouillon).14,35Micronutrient concentrations beyond these levels would require additional work to establish feasibility.Moreover, as the bouillon formulation noted above was developed for use in research, fortification levels selected for commercial products would also require testing under market conditions affecting technical and commercial feasibility (such as the impact of storage conditions on micronutrient loss and organoleptic characteristics).See Vosti et al. (in preparation) for estimates of the cost of multiple micronutrient-fortified bouillon in Burkina Faso, including considerations of affordability across different stakeholder groups.A second limitation is that we used household-level dietary data for this modeling work, which are less accurate than individual dietary recall data and require assumptions about the intrahousehold distribution of food.32To adjust for some of the common measurement errors in household food consumption data, we assessed adequacy based on the nutrient density of the household diet, but these energy-adjusted measures cannot address systematic under or over-reporting of foods that may vary in nutrient contents from the typical household diet, such as foods consumed away from home.The collection and analysis of individual-level 24-hour dietary recall data would help overcome the limitations inherent in using household-level dietary data and improve the estimates generated by similar modeling efforts.Also, while we did our best to estimate iron and zinc absorption using existing methods, these methods are not perfect, and biomarker data would be needed to confirm the prevalence of deficiency.Finally, to account for potential imperfect compliance with standards if Burkina Faso mandated F I G U R E 7 Prevalence of vitamin A, folate, vitamin B12, iron, and zinc inadequacy among children 6-59 months of age without (left panels) and with (right panels) bouillon fortification modeled to meet 30% of the Codex nutrient reference values, calculated assuming 2.5 g of bouillon consumption per day among adults (per gram bouillon: 96 µg vitamin A, 28.8 µg folic acid, 0.288 µg vitamin B12, 2.64 mg iron, and 1.68 mg zinc).See Tables S13-S17 for point estimates by region.bouillon fortification, our modeling assumed 75% of bouillon would be fortified.If more (or less) of bouillon were fortified in practice, the marginal contribution of bouillon at each modeled fortification level would change.

Food vehicle that is industrially processed/fortifiable Fortifiable food vehicle fortified to any extent Average fortification level among fortified food as a percent of the standard after adjusting for expected losses from point of fortification to households
Fortification program modeling assumptions.
TA B L E 1a Adjusted for expected micronutrient losses/degradation of 30% of vitamin A added to oil and 20% of folic acid added to wheat flour, based on expert opinion.
Among consumers, median apparent consumption of bouillon ranged from 0.9 grams per day among WRA and 0.4 grams per day among children in households of the lowest SES up to 1.2 grams per day (WRA) and 0.6 grams per day (children) in the highest SES.
5.1 grams per day for children.Like reach, median apparent quantilowest quintile of SES to 23.3 grams per day among WRA in households in the highest quintile of SES.Nationally, 82% of households reported consuming bouillon in the 7 days preceding the survey, with higher proportions of households in lower SES quintiles reporting consumption compared to households in higher SES quintiles, and a higher proportion of rural households reporting bouillon consumption compared to urban households.ifnotexplicitly stated, inadequacy refers to "apparent" inadequacy.Disparities in the prevalence of inadequacy between households of different SES and urban and rural residences were particularly pronounced for folate, vitamin B12, and iron.Based on the folate density of diets, the prevalence of folate inadequacy among WRA ranged from 24% among households in the lowest SES quintile to 46% and 44% among households in the second highest and highest SES quintiles, respectively, while folate inadequacy was 18 percentage points higher among WRA in urban households compared to rural households (Figure Apparent consumption of refined oil, wheat flour, and bouillon in the past 7 days based on the 2018−2019 Enquête Harmonisée sur les Conditions de Vie des Ménages (EHCVM) survey.
22-percentage-point disparity in iron inadequacy among WRA across household SES and a 13-percentage-point difference in iron inadequacy among WRA in urban households (30% inadequate) compared to WRA in rural households (17% inadequate).Subnational patterns of inadequacy were similar among children.minAdensity of household diets and vitamin A requirements, even among households in the highest SES quintile and among urban households (FigureS1), vitamin A inadequacy remained at or above 50% for WRA and at or above 42% for children.At the highest fortification level, the risk of high preformed retinol intakes reached 1% nationally among children (0% among WRA) and subnationally impacted 2%TA B L E 2Abbreviations: SES, socioeconomic status; WRA, women of reproductive age.a Households reporting any consumption of the food vehicle (or processed food containing the food vehicle), from household purchases, during the recall period are categorized as consuming the food vehicle.b Children 6−59 months of age.c SES quintiles based on annual per capita household expenditures as reported in the EHCVM data.SES 1 is poorest/lowest quintile of SES; SES 5 is wealthiest/highest quintile of SES.
Prevalence of apparent vitamin B12 inadequacy, nationally and by socioeconomic status (SES), with bouillon fortification at different bouillon fortification levels.Note that the modeled bouillon fortification levels (x-axis) are not always evenly spaced.SES quintiles are based on annual per capita household expenditures.SES 1 is poorest/lowest quintile of SES; SES 5 is wealthiest/highest quintile of SES.
Prevalence of apparent folate inadequacy (top) or risk of high intakes (bottom), nationally and by socioeconomic status (SES), with bouillon fortification added to existing fortification (62% of fortifiable wheat flour fortified to 12% of the national standard of 2.5 mg/kg) at different bouillon fortification levels.SES quintiles are based on annual per capita household expenditures.SES 1 is poorest/lowest quintile of SES; SES 5 is wealthiest/highest quintile of SES.lon fortified with 1.68 mg zinc per gram of bouillon was predicted to decrease the prevalence of inadequacy to between 10% (Nord Region) and 67% (Sahel Region).Among children, the prevalence of zinc inadequacy without fortification ranged from 26% in the Nord Region to 67% in the Cascades, dropping to between 21% (Nord Region) and 61% (Cascades Region) with fortified bouillon.
Prevalence of apparent zinc inadequacy (top) or risk of high intakes (bottom), nationally and by socioeconomic status (SES), with bouillon fortification at different bouillon fortification levels.Note that the modeled bouillon fortification levels (x-axis) are not always evenly spaced.SES quintiles based on annual per capita household expenditures.SES 1 is poorest/lowest quintile of SES; SES 5 is wealthiest/highest quintile of SES.
.P.A., S.A.V., and R.E.-S.designed the study and developed the methods.K.P.A., J.W.S., A.T., E.B., and K.K. made the food composition table matches.K.P.A. analyzed and modeled the data and wrote the first draft of the manuscript.All authors contributed to the data interpretation and revisions of the manuscript, and read and approved the final manuscript.