Large –scale wheat flour folic acid fortification program increases plasma folate levels among women of reproductive age in urban Tanzania
Large ±scale wheat flour folic acid fortification program increases plasma folate levels among women of reproductive age in urban Tanzania
Ramadhani A. Noor 0 1 2
Ajibola I. Abioye 2
Nzovu Ulenga 1 2
Salum Msham 1 2
George Kaishozi 2
Nilupa S Gunaratna 2
Ramadhani Mwiru 1 2
Erin Smith 2
Christina Nyhus Dhillon 2
Donna Spiegelman 0 2
Wafaie Fawzi 0 2
0 Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America, 4 Management Development for Health (MDH), Dar es Salaam, Tanzania, 5 Helen Keller International, Dar es Salaam, Tanzania, 6 Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, United States of America, 7 Department of Biostatistics, Harvard T. H. Chan School of Public Health , Boston, Massachusetts , United States of America
1 Africa Academy for Public Health (AAPH), Dar es Salaam, Tanzania, 2 Department of Global Health and Population, Harvard T. H. Chan School of Public Health , Boston, Massachusetts , United States of America
2 Editor: Marly Augusto Cardoso, Universidade de Sao Paulo , BRAZIL
There is widespread vitamin and mineral deficiency problem in Tanzania with known deficiencies of at least vitamin A, iron, folate and zinc, resulting in lasting negative consequences especially on maternal health, cognitive development and thus the nation's economic potential. Folate deficiency is associated with significant adverse health effects among women of reproductive age, including a higher risk of neural tube defects. Several countries, including Tanzania, have implemented mandatory fortification of wheat and maize flour but evidence on the effectiveness of these programs in developing countries remains limited. We evaluated the effectiveness of Tanzania's food fortification program by examining folate levels for women of reproductive age, 18±49 years. A prospective cohort study with 600 non-pregnant women enrolled concurrent with the initiation of food fortification and followed up for 1 year thereafter. Blood samples, dietary intake and fortified foods consumption data were collected at baseline, and at 6 and 12 months. Plasma folate levels were determined using a competitive assay with folate binding protein. Using univariate and multivariate linear regression, we compared the change in plasma folate levels at six and twelve months of the program from baseline. We also assessed the relative risk of folate deficiency during follow-up using log-binomial regression. The mean (±SE) pre±fortification plasma folate level for the women was 5.44-ng/ml (±2.30) at baseline. These levels improved significantly at six months [difference: 4.57ng/ml (±2.89)] and 12 months [difference: 4.27ng/ml (±4.18)]. Based on plasma folate cut-off level of 4 ng/ml, the prevalence of folate deficiency was 26.9% at baseline, and 5% at twelve months. One ng/ml increase in plasma folate from baseline was associated with a 25% decreased risk of folate deficiency at 12 months [(RR = 0.75; 95% CI = 0.67±0.85, P<0.001]. In a setting where folate
Data Availability Statement: All relevant data are
within the paper and its Supporting Information
Funding: The Helen Keller International (HKI),
Tanzania, commissioned this evaluation, HKI
SUBCONTRACT NUMBER: 6225-2012-12-00.
Design and progress of this evaluation has
received oversight by the Tanzania National Food
Fortification Alliance. The funders had no role in
study design, data collection and analysis, decision
to publish, or preparation of the manuscript.
Competing interests: The authors have declared
that no competing interests exist.
deficiency is high, food fortification program with folic acid resulted in significant
improvements in folate status among women of reproductive age.
Multiple micronutrients deficiencies including iron, folate and vitamin A are key contributors
to morbidity and mortality globally[
]. In Tanzania, anemia affects 40% of women of
reproductive age, with deficiencies in iron and vitamin A measuring 30% and 36%, respectively[
Maternal folate insufficiency has serious consequences to newborns, and among them is the
neural tube defects (NTDs)[3±5]. In Tanzania like most developing countries, limited
estimates exist on the magnitude of folate deficiency[
]. As a proxy measure and sequel of
folate deficiency among women of reproductive age, the birth prevalence of neural tube defects
(NTDs) in Tanzania is estimated to be as high as 3 NTDs per 1000 live births[
]. It is
estimated that micronutrient deficiencies cost Tanzania over US$ 518 million, estimated at 2.65%
of the country's GDP annually. Beyond the economic losses, vitamin and mineral
deficiencies are a significant contributor to infant mortality, with over 27,000 infant and 1,600
maternal deaths annually attributable to this cause[
Adequate consumption of folic acid before pregnancy and during the early weeks of
gestation decreases the risk of developing NTDs[11±14].Hence, there is a global recommendation
for peri-conceptional supplementation with 400 micrograms per day (μg/d) of synthetic folic
acid for women of child-bearing age beginning at least 1 month before conception through the
first 3 months of pregnancy[
]. High rates of unplanned pregnancies, poor adherence as
well as late reporting to ante natal care severely undermine the success of supplementation
], and the impact of continuing with the peri-conceptional
supplementation after the first trimester of pregnancy remains unclear[
Food fortification is described as the single most cost-effective public health strategy for
preventing and controlling micronutrient deficiencies[20±22]. The first cereal grain
fortification recommendations issued by the World Health Organization (WHO) was for wheat flour
and maize flour[
]. And as of 2015, 83 countries have mandated wheat flour fortification
with iron and/or folic acid; and 16 countries have mandated maize flour fortification with the
same nutrients [
]. Evidence on the public health impact of these programs suggests folic acid
fortification of flour is effective in reducing neonatal mortality and NTDs[
], however the
evidence from developing countries, particularly in Africa is limited[
]. This evaluation
was therefore designed first, to determine the prevalence of folate deficiency in this cohort of
women of reproductive age prior to a food fortification program rollout and hence validate
potential for benefit in Tanzania, and second, to assess the effectiveness of the national food
fortification program by examining prospective folate levels as a proxy measure for public
health impact in Tanzania.
Materials and methods
Food fortification program
The Tanzania National Food Fortification Program mandates fortification[
] to targeted
staple foods including salt, edible oil, wheat and maize flour Table 1. With the exception of salt,
which has been fortified with iodine since 1994, fortification of other food staples officially
started in 2013 through a mandate passed by the government of Tanzania requiring all
industrial processed wheat, maize and edible oils to be fortified. This study is limited to wheat flour
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Sodium Iron EDTA
Vitamin B12 0.1% WSa
Sodium Iron EDTA
Vitamin B12 0.1% WSa
fortification only since folic acid fortification of maize flour had not been implemented to
scale at the time of the study.
Helen Keller International worked in partnership with the Ministry of Health and Social
Welfare through Tanzania Food and Drug Authority (TFDA), the Tanzania Food and
Nutrition Centre (TFNC), the Ministry of Industry and Trade, the Tanzania Bureau of Standards
(TBS), and food producers to assist in the rollout of this mandate. To date 14 large-scale food
producers participate in the national program, including all ten of the country's wheat flour
producers, and four large-scale vegetable oil refineries. Production capacity for fortified
products among these 14 industries amounts to approximately one million metric tons (MT) of
wheat flour and 300,000MT of vegetable oil annually, or roughly 88% and 80% of the market
share, respectively. TFDA works to ensure fortified products meet the levels of quality required
by standards set by Tanzania Bureau of Standards (TBS) at production point, in the market,
and at ports of entry through regular inspections.
Using the program impact pathway adopted from a similar evaluation undertaken in Costa
Rica S1 File.[
], we mapped an impact pathway for the Tanzania Food Fortification program
and identified the scope and key areas of focus for this evaluation (Fig 1).
Study design, settings and participants recruitment
We conducted a prospective cohort study comparing participant's plasma folate levels before
and after the rollout and scale up of the national food fortification program. We enrolled
nonpregnant women of reproductive age (18±49 years) living in the Temeke and Ilala districts of
Dar es Salaam. These two districts were selected to provide a mix of urban and peri-urban
populations assuming these communities would benefit from relatively faster access to fortified
foods, given their close proximity to the main food industries in Dar es Salaam. To maintain
maximum representation with high internal and external validity, participants were recruited
from 10 clinics, 5 from each of the two selected districts, providing a 90% aggregate coverage
of antenatal care for pregnant women within the population catchment area. Given the high
rates of antenatal clinic (ANC) coverage by these clinics, we assumed that eligible participants
attending Mother and Child Health (MCH) clinics from these facilities are a representative
sample for women of reproductive age in the two districts selected for this study.
One district hospital and four health centers MCH clinics were selected from each, Temeke
and Ilala districts. We invited women attending clinics with their children for immunization
program appointments to participate in this study. We randomly selected women to
participate through a lottery system using identical folded cards with ªYESº and ªNOº labels.
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Fig 1. Program Impact Pathway (PIP) for large-scale food fortification programs. Adopted with modifications from Reynaldo Martorell
et al. Am J Clin Nutr 2015; 101:210±217. a,bAreas of focus for this evaluation in the context of Tanzania National Food Fortification program.
Women who picked ªYESº were further screened for the study. An equal number of
participants were enrolled across the ten participating sites giving a total of 60 participants from each
Since no pre-existing data on prevalence of folate deficiency and effect size from the region
could be found for reference, our sample size was calculated using estimates obtained from
similarly designed studies in Latin America[
]. Assuming a two-sided alpha of 0.05, a power
of 0.8, intraclass correlation of 0.02, and mean plasma folate levels of 10±7 and 13±9 ng/ml at
baseline and end point, respectively, we obtained a sample size of 416 participants. In order to
account for loss to follow up in this study, we inflated the sample size by roughly 50%, resulting
in a total sample of 600 women of reproductive age.
Enrolment and follow up
We enrolled 600 out of 827 women screened across the 10 study sites in Dar es Salaam (Fig 1).
Inclusion criteria was based on participants not being pregnant, based on the date of their last
menstrual period as well as a urinary test during screening, having given birth at least 9
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Fig 2. Study flow diagram on the numbers of participants enrolled and followed up during the study period.
months prior to study inclusion, planning to remain in the study area for the next 12 months,
and giving written informed consent to participate in the study. We excluded participants who
were currently or had previously taken folic acid/iron supplements during the past 9 months,
and anyone with a reported chronic illness (Fig 2).
The plasma folate status of enrolled participants was assessed at baseline, and at 6 and 12
months. During these visits, fasting blood samples of ten hours or greater were obtained to
determine the plasma folate levels. To maintain contact with our participants and to enhance
followups, we conducted home visits and phone calls to all participants during months where no clinic
visits were scheduled to provide nutrition counselling on nutrient rich diverse diets, use of
fortified foods water and sanitation practices. We also collected dietary intake data from those who
have missed their clinic visits as well as reminding participants on their upcoming clinic visit.
Written, informed consent for voluntary participation was obtained from each study
participant before enrolment. The consent process was conducted in Kiswahili, the local language.
5 / 16
The research protocol and the consent forms were reviewed and approved by the Medical
Research Review Council of the National Institute for Medical Research (MRRC±NIMR),
Tanzania and the Institutional Review Board of the Harvard T. H. Chan School of Public Health,
USA. In accordance to Tanzania standard of care, nutritional counselling was provided to all
Measurement of dietary intake
A dietary intake assessment using a semi-quantitative FFQ, validated for this setting was
conducted at baseline, and at 6 months, and 12 months of follow up to allow estimation of total
intake as well as isocaloric comparison and interpretation of the plasma folate results [
questionnaire was comprised of 108 food items commonly consumed. Participants were asked
if they had consumed these foods in the prior month, and if so, how often, and the frequencies
were converted to servings per day. A serving is based on food specific portion sizes, using the
Tanzania Food Composition Tables[
]. Using this table, we computed the food folate, which
is comparable to the dietary folate equivalents (DFE)[
] as well as total energy consumed. We
restricted data to FFQs with reasonable total energy intake, >600kcals and <4500kcals.
Specimen collection and quality control
Venous blood specimens (about 4 ml) were collected in purple top tubes containing K2EDTA
using standard venepuncture procedures, and samples were sent to the Africa Academy of
Public Health (AAPH) laboratory within two hours of collection. Once in the laboratory,
specimens were centrifuged at 3200 rpm for ten minutes to obtain plasma that was stored in a -20C
freezer in 1 to 3ml vials. Laboratory scientists made sure that specimens were free from
hemolysis, lipemia and icterus.
Plasma folate assays were done using the Cobas e411 automated analyzer (Roche
Diagnostics, Switzerland) as per manufacturer instructions. The machine was calibrated by lyophilized
human plasma with folate. Adding 1.0 ml of distilled water carefully dissolved the contents of
the calibrators. The calibrators were mixed carefully, avoiding foam formation. Aliquots of the
reconstituted calibrators were transferred into empty vials and stored at -20ÊC till needed.
Whenever required, a pair of calibrators were brought out and thawed before use at room
temperature. Testing proceeded after successful calibration, with 250±300μl of each sample run in
duplicate and average readings recorded. Negative and positive controls were used for quality
assurance in each run. Controls were run individually at least once per 24 hours while the test
was in use, once per new reagent kit and after each passed calibration. Printed results were
certified by one laboratory personnel and reviewed by another one, before entered into a
database. The normal range for the equipment is 1.5±20.0 ng/ml.
We analysed change in mean plasma folate levels from baseline, to 6, and 12 months of
followup. Mean (±SD) values of total energy intake (in calories/day), macronutrient proportions of
the total calorie intake, as well as intake of fortified wheat-based foods (in servings/day) were
calculated to estimate folic acid intake at baseline. We estimated the change in levels of these
measures from baseline, and assessed statistical significance using a paired Student's T-test.
The concentrations suggested for defining folate deficiency based metabolic indicators
range from 3±4 ng/ml [
]. This value is derived from data related to preventing
anaemia and hyperhomocysteneinemia and the public significance of applying same cut-off in
isolating folate deficiency in the context of NTDs is not fully understood[
suggests risk of NTD increases with folate insufficiency levels higher than ranges defining
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folate deficiency. We dichotomized plasma folate levels based on the stringent threshold
indicative of folate deficiency using a cut-off point of 4 ng/ml[
]. We fit univariate and
multivariate binomial regression models to assess the degree to which each unit change in
plasma folate led to a change in the risk of folate deficiency at six and twelve months, and
obtained risk ratio estimates. In multivariate models, we included potential
confounders known to be associated with folic acid intake and/or plasma folate levels, or have been
identified in regression models (p<0.2) to be significantly related to dietary intake of folic
acid at baseline. Relative risks were adjusted for age (18 to <2 6, 26 to <36 and 36±49
years), years of formal education (0±7 years, 8±11 years and 12 years), occupation
(business/professional, skilled formal, skilled informal, unskilled, unemployed), body mass index
(<18.5, 18.5 to <25, 25 to <30, 30 kg/m2), household dietary diversity score (1±12),
baseline intake of fortified wheat-based foods (servings per day), intake of vegetables and total
energy intake (kcals/day).The number of household assets were computed from a simple
count that included TV, radio, generator, fan, bike, car, couch, fridge, as well as access to
electricity and potable water, allowing classification into 3 socioeconomic groups thus: 0±5,
6±8, and 9±10 [
]. Covariates with missing data were retained in the analysis using the
missing indicator method[
].P-values were two-sided and significance was set at < 0.05.
Final data set S2 File was compiled and all statistical analyses were conducted using SAS
version 9.2 (SAS Institute Inc).
A total of 600 non-pregnant women of reproductive age were enrolled and followed for a
period of 12 months Table 2. The mean age (±SD) of the participants was 28 years (±7). A
majority of the participants had completed seven years of formal education or less (68%) and
were unemployed (51%). All the participants were found to be in the low socioeconomic class.
The mean (±SD) body mass index (BMI) was 24.4 (±5.0) kg/m2. Mean dietary folic acid intake
was low (<500μg/d) at baseline in 66% of the participants.
At baseline, the mean (±SD) energy intake based on intake surveys was 2906 kcals/day
(±966). There was significant reduction in the total energy intake among participants during
follow-up, with an average drop of 599 kcals (P<0.0001) and 700 kcals (p<0.0001), compared
to baseline at month 6 and 12 respectively. Energy intake was comprised of protein (12%), fat
(32%) and carbohydrate (56%) on average. There was a slight increase in protein intake
(0.52%; p-value = 0.006. Besides this, dietary composition was materially unchanged over the
course of follow up, with no significant change in carbohydrate as well as fat intake at any time
point. The mean (± SE) serving per day of fortified wheat-based foods at baseline was
estimated to be 0.84 (±0.56). There was significant reduction in wheat-based foods intake (-0.23
servings/day) and (-0.25 servings per day), compared to baseline intake by the sixth and twelve
month of follow-up respectively Table 3.
The mean plasma folate concentrations were 5.44 ng/ml (±2.30) at baseline, 10.08ng/ml
(±2.57) at six months and 9.70ng/ml (±3.75) at twelve months Table 4. There was an
increase of mean plasma folate of 4.57ng/ml (±2.89) from baseline to 6 months and 4.27 ng/
ml (±4.18) from baseline to 12 months. The slight drop in folate levels from six to twelve
months was not significant (p = 0.27). We compared baseline values of all variables in those
who completed the study versus those lost to follow-up, and we found no differences in
those two groups (p>0.05). Overall, there were significant reductions in the risk of folate
deficiency at six and twelve months of follow-up Table 4. There was a 25% (15%±32%)
reduction in the risk of folate deficiency at 12 months for every 1ng/ml increase in plasma
folate from baseline levels.
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Tanzania provides a model for mandatory large-scale food fortification in Africa. Our
evaluation on the effectiveness of this program demonstrates 6 months after the introduction
of the program, a significant reduction in the prevalence of folate deficiency occurred in a
cohort of women of reproductive age, with the benefit persisting up to 1 year after the program
roll-out. This evaluation provides one of the first results on effectiveness of food fortification
programs in Africa, in a setting where the prevalence of folate deficiency among women of
reproductive age was high. Our results indicate that folate insufficiency remains prevalent in
this region despite existing dietary as well as peri-conceptional folic acid supplementation
programs. Hence, there is an important role for fortification programs as a cost effective
largescale intervention to address folate and other micronutrient deficiencies [20±22]. There is
strong evidence that folate insufficiency is significantly associated with higher risk of NTDs
] and increased neonatal mortality, as well as a contributor to anaemia. Hence, preventing
folate deficiency in women of reproductive age is likely to significantly reduce child mortality
8 / 16
aWheat-based foods included bread, pancakes, cakes and donuts
N's are different at each time point due to FFQ inclusions for analysis
To our knowledge, this is the first evaluation of folic acid intake among non-pregnant
women of reproductive age using both dietary intake information and biochemical markers of
folate status in sub Saharan Africa. On average, women of reproductive age in this study,
consumed diets containing adequate energy and macronutrient distribution in compliance with
international recommendations for healthy eating[
]. At baseline, the energy intake was
comprised of protein (12%), fat (32%) and carbohydrate (56%). The mean intake values for fat and
carbohydrates did not differ markedly from the fat and carbohydrate intakes observed in other
]. However, the vast majority of women in this study did not meet the
Six months (n = 410)
0.76 (0.49, 1.18)
0.78 (0.51, 1.20)
aRelative risk (RR) estimates were obtained from binomial regression models. RR above 1 suggests an increased risk of folate deficiency for every one-unit
increase in the plasma folate. RR below 1 suggests a decreased risk of folate deficiency for every one-unit increase in the plasma folate.
bMultivariate estimates were adjusted for age in years (15±<26, 26±<36, 36), educational status in completed years (0±7, 8±11, 12), occupation
(unemployed, unskilled, skilled informal, skilled formal, business/professional), total assets (0±5, 6±8, 9±10), minimum dietary diversity score for women
(>5, 5), BMI, and the intake of wheat-based foods (<1 serving/day, 1 serving/day), vegetables (<1 serving/day, 1 serving/day) and total energy (kcal) at
cFolate deficiency was defined as plasma folate concentration <4ng/ml
dRestricted to 298 participants with follow-up at six and twelve months
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recommended intakes for folic acid intake before fortification. Similar inadequate intakes of
folic acid have also been reported among Tanzanian rural and urban children as well as among
the elderly population [
The mean serving per day of fortified wheat-based foods at baseline was estimated at 0.84,
confirming that wheat flour is an appropriate vehicle for fortification in this population. This
has direct implications for fortification programs in sub-Saharan Africa, where cereals,
including wheat flour contribute between 50±75% of energy intake, but two-thirds of the vitamins
and minerals naturally present in the unrefined staple are removed by the milling refinement
]. This fact, together with the wheat consumption observed in this study, amplifies
justification for wheat flour as a potent fortification vehicle and why mandatory fortification is
essential in this setting.
Plasma folate levels improved remarkably by month six of the study follow up, consistent with
the rollout and scale-up of national food fortification program. These findings are consistent with
other studies, that assessed the impact of the folic acid fortification programs[30,43±45], where
significant increases in folate levels and declines in folate deficiency among women have been
reported. A decline in the incidence of neural tube defects in Tanzania can be anticipated based
on the decreased prevalence of folate deficiency observed, and in line with a 46% decline in NTD
]. Improving folate status may have other critical benefits. These
may include reduced a risk of cardiovascular diseases[
], a reduced prevalence of anaemia
], protection against other birth defects[
], and against allergies and hyper allergenic
], and improved pregnancy outcomes[3±5] as well as overall healthier aging[
Despite above-mentioned benefits, several countries have not yet mandated fortification
due to concerns for potential adverse effects from large-scale population based folic acid
]. Although the evidence is limited, these concerns include potential masking of
vitamin B12 deficiency[
] and presence of unmetabolized folic acid in serum[
this has shown to be less likely in countries where increase in folic acid consumption does not
exceed 400 μg/d [
]. Supraphysiological, and possibly even physiological, folate status may
potentially favour malaria parasite growth and inhibit parasite clearance effect for some
antimalarial drugs, hence increasing malaria recrudescence[
].Further risk-benefit analysis for
folic acid fortification assessing secondary outcomes of interest such as the masking of B12
deficiency, increased levels of unmetabolized folic acid, and supraphysiologic folate status is
warranted and important for future research. It is important noticing that about 50% of
women were still deficient at 12 months, suggesting that continued efforts to enhance
supplementation would be complementary[
Our study has several limitations. First, we did not collect and test food samples to assess
the amount of fortificant contained. This limits our ability to correlate the rise in plasma folate
levels with the levels of the fortificant in the foods. We therefore assumed that most of the
wheat-based foods consumed by the participants following the launch of fortification were
made from fortified flour. The slight reduction in the mean change in folate levels we observed
at month 12 compared to month 6 was not statistically significant, and may have been due to
chance. A Tanzania Food and Drug Authority (TFDA) post marketing surveillance report of
April 2015 implies unsatisfactory and inconsistent levels of key micronutrients added in wheat
flour and edible oil and fats. Inadequate quality control at the mills, use of unacceptable
packaging materials and improper handling and storage of the fortified products along the
food chain are among the possible listed contributory factors. Results from the 2015
Tanzania national fortification assessment coverage tool (FACT) cross-sectional survey indicates
great variations in the fortification quality compared to Tanzania national standards[
Nationally only 18.9% of wheat flour and 3.3% of maize flour samples were adequately
fortified, meanwhile similar household consumption patterns in rural and urban settings being
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reported for wheat flour and maize flour at 33.1% and 2.5% respectively[
]. Second, we
experienced a gradual loss of participants over a period of 12 months of follow-up, with 33% lost to
follow up at 12 months. There was however no difference in the baseline characteristics of
participants' loss to follow-up compared to the others in the study. When we restricted analysis to
participants with complete follow-up at six and twelve months, a stronger protective
association was seen at six months, with no significant association at twelve months. Epidemiological
studies potentially suggest less risk of bias in cohort studies with up to 60% loss to follow-up or
misses when such occurs at random[
]. The pre and post comparison design for folate levels
in this cohort also reduces chances for bias. Due to full coverage nature of the fortification
program, we chose a non-experimental design `before after' design. In this case, causal attribution
is not possible. However, the observed change is significantly large to have occurred due to
other secular trends. Third, the study was conducted in an urban/ peri-urban setting where
access to fortified foods may be different compared to rural parts of the country. In sub-Saharan
Africa, wheat consumption is higher in urban compared to rural settings[
]. Therefore, maize
flour (also under the fortification program but slower to start up in Tanzania) is intended to
reach this rural population, however the number and nature of the maize industries in the
landscape mean that quality control and therefore potential effectiveness may be more limited.
Further understanding of access and consumption patterns, particularly in rural settings, remains
critical for successful implementation of the National Food Fortification program in Tanzania.
Hence, impact in rural areas should be a key objective for future studies. Finally, for logistics
and quality reasons, we performed plasma instead of red blood cell folate assays. Red blood cell
folate assays are recommended over plasma or serum folate assays, as they provide a measure of
long term rather than recent intake for folic acid[
]. Competitive assay with folate binding
protein used to measure folate concentration generally gives lower values compared to
microbiological assay using Lactobacillus rhamnosus, currently recommended as the most reliable assay
yielding comparable results for folate concentration across countries[
]. Although, it is
possible that assays performed in separate baseline, 6 and 12 months' batches introduce bias; it is
implausible for this batch effect to explain the large effect size observed.
While improving folate status has many purported health benefits, when countries state a
reason for including folic acid in flour fortification, it is usually to reduce the risk of neural
tube defects (NTDs). The WHO new guidelines on optimal serum and red blood cell folate
concentration in women of reproductive age for prevention of neural tube defects emphasizes
on the importance of assessing ªfolate insufficiencyº, instead of folate deficiency[
insufficiency implies to levels below which women are at an increased risk of having an NTD
affected pregnancy whereas folate deficiency levels forms a subset. This threshold has been
recommended for blood folate assays and not for serum or plasma levels. The blood folate cutoff
for folate insufficiency is higher than the cutoff point for folate deficiency[
]. This means that
women who are not folate deficient, can be folate insufficient and at risk of having a baby with
an NTD. Certainly the percent of women with folate deficiency represent the low end of the
percent of women at risk of having an NTD-affected pregnancy; a more accurate
representation of this risk is the percent of women with folate deficiency and insufficiency. To make
predictions on NTDs at population level using plasma folate assays, relationship between both
plasma and red blood cell folate needs first to be established in this setting. And therefore
establish corresponding threshold for plasma folate assays using red blood cell folate levels.
Similar to other countries with mandatory fortification programs, the wheat flour fortification
program in Tanzania increased folate levels for urban women of reproductive age. Using the
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impact pathway adopted for this evaluation, we can make a plausible argument that a large
scale wheat flour folic acid fortification program benefits women of reproductive age and
hence having public health impact in Tanzania. Our findings are indicative of effectiveness of
a large-scale food fortification program, and hence possible positive biological response to
other fortificants like iron, zinc and B12. The net economic benefit of food fortification
program in Tanzania is considerable; where $1 invested in central food fortification can result in
an economic return of $8.22 or an increase in GDP of 0.58%. In addition, it is estimated that
almost 6,800 deaths per year would be averted[
]. We recommend scale up of all selected
food vehicles alike, especially maize flour fortification in settings where folate and other
deficiencies are high.
S1 File. American Society for Nutrition license terms and conditions. Copyright approval
by the American Society for Nutrition.
S2 File. Folate data file.
The Helen Keller International (HKI), Tanzania, commissioned this evaluation. Design and
progress of this evaluation has received oversight by the Tanzania National Food Fortification
Alliance. We thank the study coordinators including Illuminata Ballonzi and Blandina Gomile
for contributions to the study. We also thank Simon Tatala from Tanzania Food and Nutrition
Centre (TFNC) for valuable insights during the planning phase of the study and Ellen
Hertzmark and Enju Liu for technical guidance and feedback during statistical analysis. Our
appreciation goes to Guerino Chalamilla (deceased), and Mary Mwanyika-Sando, for the grant
administrative support. RAN and AIA drafted the paper with contributions from all authors.
RAN, CND and WF designed the study; RAN, AIA, NU, GK, SM, RM and ES participated in
field implementation; RAN, AIA, NSG, DC and WF contributed to the statistical analyses. WF
and ES had full access to all of the data in the study and takes responsibility for the integrity of
the data and the accuracy of the data analysis. All authors contributed to the development of,
and read and approved the final version, of the manuscript.
Conceptualization: Ramadhani A. Noor, George Kaishozi, Nilupa S Gunaratna, Christina
Nyhus Dhillon, Wafaie Fawzi.
Data curation: Ajibola I. Abioye, Nzovu Ulenga.
Formal analysis: Ramadhani A. Noor, Ajibola I. Abioye.
Funding acquisition: Ramadhani A. Noor, Christina Nyhus Dhillon, Wafaie Fawzi.
Investigation: Nzovu Ulenga.
Methodology: Ramadhani A. Noor, Ajibola I. Abioye, Nzovu Ulenga, Nilupa S Gunaratna,
Project administration: Ramadhani A. Noor, Salum Msham, George Kaishozi, Ramadhani
Mwiru, Christina Nyhus Dhillon.
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Resources: George Kaishozi, Erin Smith, Christina Nyhus Dhillon.
Software: Ajibola I. Abioye.
Supervision: Donna Spiegelman, Wafaie Fawzi.
Validation: Ajibola I. Abioye, Nilupa S Gunaratna, Erin Smith, Christina Nyhus Dhillon,
Donna Spiegelman, Wafaie Fawzi.
Visualization: Ramadhani A. Noor, Ajibola I. Abioye, Nilupa S Gunaratna, Ramadhani
Mwiru, Donna Spiegelman, Wafaie Fawzi.
Writing ± original draft: Ramadhani A. Noor.
Writing ± review & editing: Ramadhani A. Noor, Ajibola I. Abioye, Nzovu Ulenga, Salum
Msham, George Kaishozi, Nilupa S Gunaratna, Ramadhani Mwiru, Erin Smith, Christina
Nyhus Dhillon, Donna Spiegelman, Wafaie Fawzi.
13 / 16
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Monitoring and Evaluation Plan Tanzanian National Food Fortification Program. 2012;
58. TFDA. THE POST MARKETING SURVEILLANCE OF FORTIFIED FOOD IN TANZANIA (Large scale
producers of wheat flour and vegetable oil). Dar es Salaam;
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