Optimal formulations of local foods to achieve nutritional adequacy for 6 23-month-old rural Tanzanian children

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1 FOOD & NUTRITION RESEARCH, 2017 VOL. 61, ARTICLE Optmal formulatons of local foods to acheve nutrtonal adequacy for 6 23-month-old rural Tanzanan chldren Jofrey Raymond a, Neema Kassm a, Jerman W. Rose b and Morrs Agaba a a School of Lfe Scence and Boengneerng, Nelson Mandela Afrcan Insttuton of Scence and Technology (NM-AIST), Arusha, Tanzana; b SolBrdge Internatonal School of Busness, Woosong Unversty, Daejeon, Republc of Korea ABSTRACT Background: Achevng nutrtonal goals of nfants and young chldren whle mantanng the ntake of local and culture-specfc foods can be a dauntng task. Det optmsaton usng lnear goal programmng (LP) can effectvely generate optmal formulatons ncorporatng local and culturally acceptable foods. Objectve: The prmary objectve of ths study was to determne whether a realstc and affordable det that acheves detary recommended ntakes (DRIs) for 22 selected nutrents can be formulated for rural 6 23-month-old chldren n Tanzana. Desgn: Detary ntakes of 400 chldren aged 6 23 months were assessed usng a weghed detary record (WDR), 24-hour detary recalls and a 7-days food record. A market survey was also carred out to estmate the cost per 100 g of edble porton of foods that are commonly consumed n the study area. Detary and market survey data were then used to defne LP model parameters for det optmsaton. All LP analyses were done usng lnear program solver (LPS) verson to generate optmal food formulatons. Results: Optmal formulatons that acheved DRIs for 20 nutrents for chldren aged 6 11 months and all selected nutrents for chldren aged months were successfully developed at a twofold cost of the observed food purchase across age groups. Optmal formulatons contaned a mxture of ngredents such as wholegran cereals, Irsh potatoes, pulses and seeds, fsh and poultry meat as well as fruts and vegetables that can be sourced locally. Conclusons: Our fndngs revealed that gven the avalable food choces, t s possble to develop optmal formulatons that can mprove detary adequacy for rural 6 23-month-old chldren f food budget for the chld s dets s doubled. These fndngs suggest the need for settng alternatve nterventons whch can help households ncrease access to nutrent-dense foods that can fll the dentfed nutrent gaps. ARTICLE HISTORY Receved 21 January 2017 Accepted 14 July 2017 KEYWORDS Optmal food formulatons; local foods; nfants and young chldren; lnear programmng; Tanzana Introducton Adequate nutrton durng the frst 1000 days, begnnng at concepton and extendng through to the second brthday of a chld, s a crtcal wndow for preventng undernutrton and ts long-term consequences [1 3]. Poor feedng practces durng ths vulnerable perod can ncrease the rsk of undernutrton, morbdty and mortalty of nfants and young chldren. Early-chldhood undernutrton can mpar the physcal and cogntve development of a chld and can also weaken the ablty of the chld to fght aganst deadly nfectous dseases [4]. In the long term, early chldhood undernutrton can lead to reduced school performance, lower economc productvty, shorter adult stature and decreased offsprng brth weght [2,4 6]. Most households n Sub-Saharan Afrca (SSA) do not have adequate nutrton knowledge for decson makng that accounts for the full cost beneft analyss of a balanced det. Feedng practces n typcal Afrcan households are mostly geared to abettng hunger as a sngularty [7], and so nutrton s rarely consdered or factored nto food securty strateges. Furthermore, the percepton that nutrent-rch meals are expensve, coupled wth tradtonal notons of what consttutes food ( food s maze ), and mssed opportuntes around other foodstuffs contrbutes to undernutrton, especally, among low-ncome urban and most rural households [8]. As a result, n SSA, more than 38.5% (>56 mllon) chldren are stunted, 19.6% (30 mllon) are underweght and 9.0% (15 mllon) are wasted. Smlarly, defcences of essental mcronutrents such CONTACT Jofrey Raymond jofrey.raymond@gmal.com School of Lfe Scence and Boengneerng, Nelson Mandela Afrcan Insttuton of Scence and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzana Supplemental data for ths artcle can be accessed here The Author(s). Publshed by Informa UK Lmted, tradng as Taylor & Francs Group. Ths s an Open Access artcle dstrbuted under the terms of the Creatve Commons Attrbuton Lcense ( whch permts unrestrcted use, dstrbuton, and reproducton n any medum, provded the orgnal work s properly cted.

2 2 J. RAYMOND ET AL. as vtamns A, folc acd, ron, odne, calcum and znc are extensve and have devastatng mpacts [9]. In Tanzana partcularly, more than one-thrd (35.5%) of chldren under 2 years of age are facng chronc undernutrton [10]. Mcronutrent defcences among chldren are common, and prevalence of anaema, ron and vtamn A defcency among chldren aged 6 23 months are 73%, 42% and 33%, respectvely [11]. Poor nfant and young chld feedng (IYCF) practces are among the man causes of the prevalent chldhood malnutrton n the country. The analyss of data from Tanzana Demographc Health Survey (TDHS) showed that sugary foods (13%) are more frequently consumed than mcronutrent-rch foods such as fortfed nfant cereals (4%), eggs (8%) and vtamn-a-rch fruts (0%) [12]. Ths evdence suggests a general need to mprove IYCF practces n SSA communtes. The use of locally avalable nutrent-dense foods can sustanably mprove complementary feedng practces n a target populaton [13]. The lnear programmng (LP) approach can facltate the optmal use of locally avalable foods to mprove the detary adequacy of vulnerable populatons [14]. The LP approach needs to be carred out based on local avalablty and accessblty of nutrent-dense foods n the target populaton [15]. Several studes have reported mxed results on the ablty of local foods to meet nutrent requrements for chldren n low-ncome countres. One study n Kenya, for nstance, showed that LP modelled dets from local foods could acheve nutrent requrements for young chldren aged months [16]. In contrast, the same Kenyan study revealed that local foods could not meet mcronutrent requrements for nfants aged 6 11 months even after ntegratng wld foods to the LP model [16]. Another study n Mozambque showed that optmal combnatons of locally avalable foods can meet all mcronutrent recommendatons for young chldren aged months [17]. However, the Mozambque s study used EARs nstead of RNIs n the LP models, meanng that the selected det would not meet the requrements of 50% of the populaton for those nutrents at 100% of the EAR. Two recent studes n Kenya that used RNIs n LP models showed that t s dffcult to acheve nutrent requrements for nfants and young chldren usng locally avalable foods only [15,18]. Despte the mxed results from prevous and recent studes, the LP has proven useful n dentfyng the cheapest possble combnaton of food ngredents that meet a set of nutrtonal requrements n low-ncome communtes [19]. The LP tool has also proven useful n predctng lmtng nutrents [20] and assessng the cost-effectveness and economc value of food fortfcaton n a populaton [21]. The LP can, therefore, help practtoners to develop realstc and affordable formulatons n resourcepoor communtes. The prmary objectve of the present study was to determne whether a realstc and affordable det that acheves detary recommended ntakes (DRIs) for selected nutrents can be formulated for rural month-old chldren n Tanzana. Methods Study ste The study was conducted n sx randomly selected vllages out of 59 n Bah Dstrct, the central zone of Tanzana. Ths dstrct was purposvely selected because t s located n the regon wth hgh prevalence of stuntng among nfants and young chldren under two years of age [22]. Study desgn A cross-sectonal survey was conducted from September to December 2015 durng the dry season to assess detary consumpton patterns of 400 chldren aged 6 23 months. A market survey was also carred out to determne the cost per 100 g of edble porton of local foods commonly consumed n the study populaton. Detary and market survey data were then used to defne LP model parameters for det optmsaton. All the analyses were done usng MS Excel 2013 and lnear program solver verson (LPS) to generate an optmal soluton. Addtonally, anthropometrc z scores for nfants and young chldren were calculated based on WHO s 2006 Chld Growth Standards [23] wth the use of ProPAN software (verson 2.0). A chld was categorsed as wasted, underweght or stunted f hs or her z-scores for weght-for-length, weght-for-age or length-for-age were less than 2 SD. Subjects and samplng Sx vllages were randomly selected from 59 vllages n Bah Dstrct and 67 chldren were randomly selected from each vllage [24]. The ncluson crtera were that a chld was 6 23 months of age nclusve and that hs or her prmary caregver was avalable for and agreed to partcpate n the study survey. Moreover, the chld was supposed to be healthy and not sufferng from any dsablty that may affect hs or her detary ntakes. If more than one chld n a household met the ncluson crtera, then one was randomly selected. Food consumpton pattern Detary data were collected usng 24-hour detary recalls, weghed detary record (WDR) and 7 days

3 FOOD & NUTRITION RESEARCH 3 food records descrbed n prevous studes [24 26]. The WDR method was used to collect data on food consumpton for 7 days; 24-hour detary recalls and 7-day food records were used to descrbe food patterns n 7 days. Food porton szes were not collected for the 24-hour recall and 7-day food records. A sngle 24-hour recall was done to obtan nformaton on foods and beverages consumed wthn 24 hours before the WDR day. Durng the ntervew, mothers were asked to recall all foods and beverages consumed by ther nfants n the past 24 hours. To help dentfy foods consumed, pctures and food models were shown to a mother or a caregver so that she or he could pont out the food tems. Mothers were also asked to menton other foods and beverages that were not ncluded n our food models and pctures. In the WDR method, all foods and beverages consumed by a chld were weghed usng an electronc ktchen scale (CAMRY, Model EK3131, precson ±2 g) and recorded. A researcher was present at the household for 12 hours of the day to observe and wegh the amount of all foods and beverages served and consumed by the chld as well as leftovers. A 12-h recall for all foods and beverages consumed after the observer has left the household was also collected. Then, mothers were asked to estmate the amount of recalled foods n local cups or utensls, and the estmated amount was then weghed usng the real food models. All composte foods and dshes were broken down nto ther ndvdual ngredents such as added ol, baobab powder, sugar, salt, tomato, carrots, onons, and so forth. WDR were collected on all days of the week to account for the effect of each day of the week on detary ntakes of the subjects. In the case of 7-days food records, a self-admnstered 7-day food tally was done to obtan nformaton on the frequency of foods and beverages consumed after the WDR day. In ths approach, the prmary caregvers were asked to record all foods and beverages consumed by ther chldren durng the 7-day perod. For the llterate prmary caregvers and those who forgot to record foods consumed, a 12-hour recall was then performed. Market survey A market survey was also conducted n one local market, whch was often used by mothers n each vllage. Only one prce per food tem was collected n small shops avalable n each vllage. If the survey locaton had a market wth multple vendors, three dfferent prces per food tem were collected, and an attempt was made to nclude both the hghest and lowest prces across all vendors. For cooked composte dshes, each raw ngredent was weghed and ther costs were summed to obtan the cost for all ngredents. The fnal cooked food was also weghed, and the cost per 100 g of cooked food or composte dsh was then estmated. The cost was lnked to the food composton database for our LP models. Preparaton of model parameters Data from the detary assessment survey defned the model parameters. The preparaton of LP model parameters was done n Mcrosoft Excel These parameters ncluded food subgroups, a medan servng sze for each food subgroup, the lower, medan, and upper lmts of servng szes, and the maxmum number of servngs per week for food groups and food subgroups. Food subgroups were defned by grams (servng szes) of ndvdual foods that were consumed by 5% of chldren and nutrent-dense foods consumed by 5%. The servng sze for each food subgroup was defned by the medan servng sze for chldren who consumed the food n each age group. The lower, medan and upper lmts of servng szes were defned as 10th, the 50th and 90th percentle of food patterns for all nfants and young chldren n each age group. The maxmum number of servngs per week for optmal food patterns was defned as 1, 2, 3, 4, 5, 6 or 7 when 0 5%, 6 12%, 13 22%, 23 34%, 35 47%, 48 65% and %, respectvely, of the chldren consumed the food [26]. These LP parameters were used to set up the LP models for the analyses n LPS software verson The dets were modelled for a 7-day perod. Food composton database Detary ntakes of nutrents were estmated based on Tanzana Food Composton Tables (TFCT) [27] and Unted States Department of Agrculture Food Composton Database (USDA) [28]. In some cases, the amount of foods served and consumed were converted to ther raw form usng cooked to raw converson factors so as to match nutrent values n food composton databases [24]. An average of 33 food tems appeared n the detary records and were categorsed nto seven major food groups and 11 food subgroups based on the WHO food groups and culnary usage for both breastfed and non-breastfed nfants and young chldren aged 6 23 months [29]. The seven major food groups ncluded: grans, roots and tubers; legumes, nuts and seeds; dary products; flesh foods; eggs; vtamn-a rch fruts and vegetables, other fruts and vegetables; and a mscellaneous group. The nutrent profles were created based on 7- days weghed ntakes usng medan proporton weghts per food tem. In order to avod

4 4 J. RAYMOND ET AL. overestmaton, nutrent values for the foods consumed n cooked state were adjusted for cookng losses usng USDA retenton factors [30]. Nutrent profles were calculated separately for each age group and were used as nput data for our LP models. Objectve functon of lnear programmng models The objectve functon was to mnmse devatons from the populaton s food sub-group patterns for 11 food sub-groups whle smultaneously meetng the requred detary standards. Based on the study by Okubo et al. [31], the objectve functon s represented by: Y ¼ Xn ¼1 ðq opt Q obs Þ=Q obs where Y denotes the objectve functon to mnmse, and Q opt denotes the quantty (g) of food subgroup n the optmsed food ntake pattern, and Q obs denotes the medan quantty (g) of food subgroup n the observed food ntake pattern. The absolute value Y was nonlnear. In order to apply LP, we had to transform Y nto a lnear functon usng goal programmng approach descrbed n prevous studes [19,31,32]. New decson varables 0, representng postve (P 1 to P 33 ) and negatve (N 1 to N 33 ) devaton from the quantty of the observed food subgroup, were created and defned as follows: If Q opt If Q opt If Q opt < Q obs < Q obs then N ¼ðQ obs then N ¼ 0 and P ¼ ðq opt < Q obs then N ¼ 0; and P ¼ 0: Subject to : P N ¼ðQ obs Q opt Þ=Q obs and P ¼ 0: Q obs Þ=Q obs : Q opt Þ=Q obs : The new lnear functon termed Yʹ was expressed as the sum of the devatonal varables and mnmsed as follows: Mnmze Y 0 ¼ Xn ¼1 ðn þ P Þ where N and P are negatve and postve devatonal varables representng devatons from the th goal. Each food subgroup n the objectve functon was lnked to the nutrent profle and cost databases establshed for the present study. The model calculated the ntake of food subgroups at all tmes and checked whether nutrtonal constrants were satsfed. The observed ntake of each food subgroup was defned accordng to the medan ntake of that food subgroup across the whole populaton. Nutrtonal constrants for lnear programmng models We ntroduced a set of constrants to our LP models to mnmse the gap between observed and optmsed food ntake patterns. The ntenton was to ensure that the soluton selected by a model satsfes each of the specfed constrants. Food use lmts were set to ensure that program models dd not exceed the amount of foods that s usually consumed by the target populaton. These lmts were derved from the actual ntake patterns for each age group as reported n a 12-hour WDR. The detary ntake of all foods from each food subgroup was requred not to exceed the 90th percentle of ntake for each age group. Food group and subgroup constrants were defned by the grams of ndvdual foods n each age group. Food ntakes were constraned wthn the range from the 10th percentle to 90th percentle of the observed ntakes for each age group [31]. In the present study, however, the ntake of small dred fsh (sardnes), meat, vegetables, fruts and seeds was very low. For these foods, we, therefore, had to exceptonally set a maxmum ntake level to 90th percentle for each age group amng to promote consumpton of these nutrent-dense foods. Nutrtonal constrants were ncluded to ensure that the nutrtonal content of each optmsed food ntake pattern was equal to or greater than the desred value, whch was based on the DRIs for nfants and young chldren. DRIs for the selected nutrents such as proten, calcum, ron, znc, copper, magnesum, manganese, phosphorus, potassum, sodum, vtamn A (RE), folate, vtamn B 1, vtamn B 2 nacn, vtamn B 6, vtamn B 12, vtamn C, vtamn D, vtamn E and pantothenc acd publshed by the World Health Organzaton (WHO) for nfants and young chldren [33] was the crteron for determnng whether each nutrtonal goal had been acheved by the optmsed food ntake pattern. Our LP model assumed low boavalablty of ron and znc. In some cases, tolerable upper ntake level (UL) was also used to create acceptable nutrent ranges. Energy constrant for moderately breastfed chldren was also ncluded n the model to ensure that the energy content of the optmsed food ntake pattern was equal to the estmated energy requrement (EER) for each age group. The energy and nutrent contrbuton from breast mlk was taken nto account to ensure that the realstc dets were selected. Snce the mean breast-mlk ntakes for the study populaton were unknown, we, therefore, used the publshed WHO average breast mlk ntakes of 660 g/d, 616 g/d and 549 g/d for chldren aged 6 8 months, 9 11 months and months, respectvely, n our LP models [34]. In addton, the cost

5 FOOD & NUTRITION RESEARCH 5 Table 1. Soco-demographc characterstcs of the study populaton (n = 400 chld mother pars). Varable Mean/Frequency Std. Devaton/ (%) Mn, Max Age Age of the respondent sd 16,56 Head of household If respondent s head of household Martal status Marred Sngle Wdowed Separated Maternal educaton Illterate Read and wrte Prmary Secondary Tertary Household sze Number of people lvng n the household sd 2,14 Chld nutrton status (aged 6 23 months) Heght-for-age z-score < 2 SD constrant was set to ensure that the cost of the optmal formulaton was equal to the maxmum cost of all dets consumed by the chldren n each age group. Results Characterstcs of subjects Four hundred nfants and young chldren from 400 predomnantly rural households were surveyed n Bah Dstrct n Dodoma Regon of central Tanzana. Among the 400 subjects, 50% were chldren aged months, 25% were nfants aged 9 11 months and 25% were nfants aged 6 8 months. Overall, 40% of chldren n the study area were facng chronc undernutrton,.e. ther heght-for-age z-scores were less than 2 SD (Table 1). All nfants and young chldren n the present study were stll beng breastfed at the tme of the survey. Optmal food ntake patterns Optmal food patterns were generated and the dfferences between observed and optmsed food ntake patterns were establshed (Table 3). In the present analyss, the dfference between observed and optmal ntakes of fruts was 3.6, 23.8 and 17.4 g for chldren aged 6 8, 9 11 and months, respectvely. Also, the dfference between observed and optmal green and yellow vegetable ntake was g for chldren aged 6 8, 86.3 g for chldren aged 9 11 months and 184 g for chldren aged months. Smlarly, the dfference between observed and optmsed ntakes of flesh foods (fsh and meat) was 0.6 g for chldren aged 6 8 months,28.7 g for chldren aged 9 11 months and47.2gforchldrenaged12 23 months. Furthermore, the dfference of 24.5, 34.0 and 26.2 g for chldren aged 6 8, 9 11 and months, respectvely, was observed n oly seed ntakes. Eventually, a total dfference of 4.2, 4.9 and 4.2 g for chldren aged 6 8, 9 11 and months respectvely was observed n a mscellaneous food group such as fats/ol, salt and sugar. Observed food patterns The total of 28, 32 and 42 food tems were reported n the detary data for chldren aged 6 8 months, 9 11 months and months, respectvely. The observed dets were manly cereal-based, wth few anmal-source foods across all age groups. From the lst of all foods, seven major food groups were formed based on the WHO food groups for both breastfed and nonbreastfed nfants and young chldren aged 6 23 months [29]. Man food groups that were formed nclude grans, roots and tubers; legumes, nuts and seeds; dary products; flesh foods; eggs; vtamn-a rch fruts and vegetable; other fruts and vegetables; and a mscellaneous group. In addton, the 10th, 50th and 90th percentles of the observed ntake of all foods that could be successfully promoted were establshed across age groups (Table 2). Nutrent profles for observed and optmsed dets The nutrent profles for observed and optmsed food patterns were generated n each age group (Table 4). Based on the reference detary ntake values publshed by WHO for nfants and young chldren [33,35,36], our results showed that the number of nutrents for whch nutrtonal goals were not acheved n the observed food ntake pattern was sx for nfants aged 6 8 months, three for nfants aged 9 11 months, and three for chldren aged months. The number of nutrents for whch the nutrtonal goals were not acheved n the optmsed dets was two for both chldren aged 6 8 and 9 11 months. Optmal formulaton for chldren aged months acheved the nutrtonal goal of DRIs for all 22 studed nutrents ncludng energy, proten, calcum, ron, znc, copper, magnesum, manganese,

6 6 J. RAYMOND ET AL. Table 2. Food group and sub-food group constrants ncluded n lnear programmng models. 6 8 months (n = 100) 9 11 months (n = 100) months (n = 200) Lower Average a Upper Lower Average a Upper Lower Average a Upper Food group (g/day) Subgroup (g/day) P10 P50 P90 P10 P50 P90 P10 P50 P90 Grans, roots and tubers Whole grans, flour Refned grans, flour Irsh potatoes, raw Sweet potatoes, raw Legumes, nuts and seeds Seeds, dred, raw Pulses, dred, raw Dary products Cow mlk, raw Flesh foods Meat Fsh, dred Eggs Egg, boled Vtamn-A rch fruts and vegetables Fruts Green and yellow vegetables Other fruts and vegetables Others Fats and ols Salt Sugar a Average servng szes were based on the number of observed medan servngs of food n each food subgroup. Table 3. Comparson of food quanttes (g/day) between observed and optmsed food ntakes. 6 8 months (n = 100) 9 11 months (n = 100) months (n = 200) Food group Subgroup Observed Optmsed Observed Optmsed Observed Optmsed Grans, roots and tubers Whole grans, flour Refned grans, flour Irsh potatoes, raw Sweet potatoes, raw Legumes, nuts and seeds Seeds, dred, raw a a a Pulses, dred, raw a Dary products Cow mlk, raw Breast mlk Human mlk b Flesh foods Meat, raw a a a Fsh, dred a a a Eggs Egg, boled Vtamn-A rch fruts and vegetables Fruts a a a Green and yellow vegetables a a a Other fruts and vegetables Others Fats and ols Salt Sugar Total cost TZS (USD) 500 (0.3) 1122 (0.6) 780 (0.4) 1335 (0.7) 1325 (0.7) 2650 (1.3) a 90th percentle upper lmt constrant was reached for the food group and subgroup patterns. The amount of breast mlk was estmated from values publshed by WHO [34]. phosphorus, potassum, sodum, folate, nacn, vtamn A, vtamn B1, vtamn B12, vtamn B2, vtamn B6, vtamn C, vtamn D, vtamn E and pantothenc acd. Dscusson Age-specfc optmsed food ntake formulatons that acheved a set of nutrent recommendatons were generated usng LP models gven the DRIs for nfants and young chldren aged 6 23 months n developng countres. The present analyss demonstrates how nutrent-based recommendatons can be turned nto nutrtonally adequate food ntake patterns wth mnmal modfcaton of current feedng practces among young chldren n low-ncome communtes. Most of our optmsed food ntake patterns ranged wthn 10th and 90th percentle lmts of the observed

7 FOOD & NUTRITION RESEARCH 7 Table 4. Comparson of nutrent contents between observed and optmsed daly food ntake patterns. 6 8 months (n = 100) 9 11 months (n = 100) months (n = 200) Nutrents c Observed b Optmsed Observed b Optmsed Observed b Optmsed Energy (Kcal/day) Proten (g/day) Calcum (mg/day) a a Iron (mg/day) 4.8 a 9.7 a 6.1 a 10.6 a 7.0 a 11.7 Znc (mg/day) 3.0 a Copper (mg/day) Magnesum (mg/day) Manganese (mg/day) Phosphorus (mg/day) a Potassum (mg/day) Sodum (g/day) c Folate (μg/day) Nacn (mgne/day) a 10.3 Vtamn A (μgre/day) Vtamn B1 (mg/day) 0.7 a Vtamn B12 (μg/day) Vtamn B2 (mg/day) Vtamn B6 (mg/day) Vtamn C (mg/day) Vtamn D (μg/day) 1.0 a 4.1 a 3.6 a 4.2 a 4.4 a 6.8 Vtamn E (mg/day) Pantothenc acd (mg/day) a Nutrents not meetng the detary recommended ntakes (DRIs). b Observed ntake of nutrents n each age group was based on the medan populaton ntake of nutrents. c Amount of breast mlk ntake used to calculate energy and nutrent ntakes was (g/day), (g/day) and (g/day) for chldren aged 6 8 months, 9 11 months and months, respectvely [34]. ntake patterns at food group levels (Table 3), demonstratng that the acheved soluton s wthn the cultural eatng habts of the study populaton. In addton, the ntake of some baselne nutrent-dense foods such as seeds, fsh, meat, fruts and vegetables reached the upper lmt (90th percentle). Ths fndng ndcates that the consumpton of foods wthn these food groups needs to ncrease. For easer nterpretaton of data, we assumed that detary modfcaton was requred when the dfference between observed and optmsed food ntake patterns was more than 10%. In the analyss, we observed that though nutrtonal constrants set by DRIs dd not dffer sgnfcantly between age groups, detary modfcatons that were needed to acheve the generated nutrtonal goals dffered accordng to age group. Fruts and vegetables, for example, needed to be ncreased by 119, 110 and 172% for chldren aged 6 8, 9 11 and months, respectvely. Also, foods of anmal source such as fsh and poultry meat needed to be ncreased by 526% for chldren aged 6 8 months, 401% for chldren aged 9 11 months, and 410% for chldren aged months. Lkewse, our analyss revealed that a 257, 236 and 58% ncrease of pulses and seeds were needed for chldren aged 6 8, 9 11 and months, respectvely. The present analyss demonstrated that meetng nutrtonal goals for the studed populaton requres a consderable ncrease n the consumpton of nutrent-rch foods such as fruts, seeds and anmal source foods for all age groups. These fndngs agree wth reports from prevous studes on the use of LP to mprove the ntake of problem nutrents among Myanmar and Kenyan chldren under two years of age [3,18]. Nutrent-based detary gudelnes for feedng Tanzanan chldren aged 6 23 months are not well documented, makng t dffcult to compare our modelled dets wth those of other studes. The present analyses mght, therefore, contrbute to the mprovement of detary gudelnes for nfants and young chldren n low-ncome communtes n Tanzana. The optmsed food ntake patterns called for a marked reducton of refned grans to keep consumpton of whole grans wthn at least 10th percentle lmt n all age groups. The optmsed models revealed a zero ntake of salt so as to mantan the consumpton of sugar and vegetable ol wthn at least 10th percentle across all age groups. Nevertheless, the gap between observed and optmsed food ntake patterns n chldren aged 6 8 months was to some extent hgher than n other age groups. These results were slghtly consstent wth food choces recommended n Canada s Food Gudelnes [37]. However, the reasons for dfferences n the degree of detary modfcaton requred for each age group are unclear, though they mght be explaned based on exstng age-specfc feedng practces. The observed ntake of most nutrent-dense foods was relatvely lower n chldren aged 6 8 months compared to older age groups (Table 3). Also, the energy requrement was relatvely lower n nfants aged 6 8 months

8 8 J. RAYMOND ET AL. compared to older groups. Thus, achevng nutrtonal goals for nfants aged 6 8 months needed a substantal ncrease n nutrent-dense foods such as pulses and seeds, small dred fsh, fruts and vegetables. Prevous studes conducted n Kenya reported smlar fndngs about the requred detary modfcaton based on age group [15,18]. These two Kenyan studes revealed that achevng nutrtonal goals for nfants and young chldren needs addtonal modfcaton to local dets. Such nterventons may nclude low-cost fortfed foods, ncreased access to anmal-source foods or home fortfcaton strateges usng mcronutrent powders. Our present analyss showed that about 70% of all studed nutrents met the RDI usng the observed food patterns. The number of nutrents that acheved recommended ntakes reached 91% for chldren aged 6 11 months and 100% for chldren aged months after usng det optmsaton models. Ths ndcates that our modelled dets from local foods could mprove the nutrtonal qualty of complementary foods for rural Tanzanan chldren aged 6 23 months. However, t should be noted that although our optmal modelled dets acheved nutrtonal goals for chldren aged months, the optmal formulaton contaned exactly 100% RDIs of ron and nacn, ndcatng that these are lmtng nutrents n the studed populaton. Also, one should note that modelled dets acheved only 50% RDI for ron n nfants and young chldren aged 6 8 months and 9 11 months, suggestng that ron s the problem nutrent n a populaton. Iron defcency durng 6 23 months of age has been assocated wth mpared cogntve performance and other rreversble potental lfelong behavour changes whch can lmt a chld s ablty to beneft from economc opportuntes n adulthood [38]. Ths underscores the need for desgnng a cost-effectve nutrton nterventon that can meet RDIs for the dentfed problem nutrents n the populaton. In the present study, a mxture of whole grans flour and Irsh potatoes (33 g), pulses and seeds (47 g), dred sardnes and other anmal source foods (5.6 g) and vtamn A rch fruts and vegetables (228 g) acheved the RDIs for 20 selected nutrents at a cost of 1122 Tanzanan shllngs per day (TZS/day) (approxmately 0.6 USD/day), whch doubles the cost of the observed average food cost per day for a chld aged between 6 8 months. Smlarly, a mxture of whole grans flour (61 g), pulses and seeds (41 g), dred sardnes and other anmal source foods (36 g) and vtamn A rch fruts and vegetables (224 g) acheved the RDIs for 20 selected nutrents at a cost of 1335 TZS/day (approxmately 0.7 USD/day), whch s approxmately twce the observed cost of food purchase per day for a chld aged 9 11 months old. Lkewse, a mxture of whole grans flour (85 g), pulses and seeds (44 g), dred sardnes and other anmal source foods (59 g) and vtamn A rch fruts and vegetables (348 g) acheved the daly ntake recommendatons for all selected nutrents at a cost of 2650 TZS/day (approxmately 1.3 USD/day), whch s a twofold ncrease of the observed food purchase cost for a chld aged between 12 and 23 months. These results suggest that the alternatves for mprovng detary adequacy of lmtng nutrents are avalable but at a relatvely hgher cost than observed cost across all age groups. The ncrease n cost may affect the feasblty of optmal formulatons n a populaton, especally n poor famles. These fndngs propose the need for assessng det patterns n other seasons as well as n other areas to dentfy other local, low-cost, nutrent-dense foods that can overcome the dentfed mcronutrent gaps at an affordable cost for the studed populaton. As n smlar studes from other countres such as Indonesa, Myanmar and Camboda, t was observed that essental mcronutrents such as ron, znc and calcum were the most dffcult constrants to acheve gven the exstng complementary feedng practces [3,25,26,39]. Even though our modelled dets could not acheve DRIs for vtamn D, we dd not regard ths vtamn as a problem nutrent. Ths s because suffcent sun exposure could address the defcency of vtamn D [40]. Our LP analyss showed that optmsng the use of locally avalable nutrent-dense foods can mprove recommended detary ntakes (RDIs) for nutrents lke ron, znc and calcum that are frequently reported as lmtng nutrents among rural nfants and young chldren n developng countres. The fnal optmal formulatons of the present study contaned a varety of food ngredents such as wholegran cereals (maze flour, mllet, rce, wheat), Irsh potatoes, small dred fsh (sardnes), fruts (baobab powder), dred pulses, nuts and seeds (soybeans, peanuts, sesame seeds) and vegetables that can be sourced locally n the communty. Also, fnal formulatons contaned a mxture of ngredents that can naturally ncrease the boavalablty of ron, znc and vtamn A whch are usually n a non-boavalable form n most typcal SSA dets [41,42]. The baobab powder n the mxture, for example, s a rch source of ascorbc acd, whch s a well-known ron absorpton enhancer [43,44]. Fsh and poultry meat can ncrease the boavalablty of ron and znc n the modelled formula [44]. In addton, sesame seeds n the mxture provde essental ols that can enhance the boavalablty of beta-carotene n the formulaton

9 FOOD & NUTRITION RESEARCH 9 [45]. The modelled dets contaned ron and znc absorpton nhbtors such as phytates n whole gran cereals, seeds and legumes. Thus, expermental studes are needed to ascertan the bologcal value of essental nutrents n our optmal food formulatons. Any future changes n the avalablty of local foods or prce can be modfed usng the LP approach to generate deal formulatons that accommodate changes. Our goal s to ensure that the modelled formulatons are avalable n areas wth hgh prevalence of undernutrton. Despte the dentfed strengths, ths study has some lmtatons. The nutrent content of some canddate ngredents were mssng from Tanzana s Food Composton Tables, compellng us to use food composton databases from other countres. The content of nutrents n food s known to vary based on varety and locaton. Ths mght have affected the results of our study, especally f the nutrent database of the modelled local foods n the fnal formulaton was not accurate [3,46]. Also, we used medan porton szes above the 90th percentle forsomedentfedpotentalfoodsaswebelevedthat these foods could be successfully promoted. However, the feasblty of adoptng these formulatons may be dffcult at the populaton level. Another lmtaton s that, gven the range of the present study, our analyss dd not take seasonalty nto account. As such, nutrent ntakes and food consumpton patterns dentfed refer bascally to the dry season of the study area. Comprehensve studes, therefore, are needed to verfy the effect of seasonalty on food avalablty and consumpton habts n the study populaton. Moreover, even though the models mnmse devatons from the observed medan sub-group patterns, the model wll select the foods of hghest nutrent content n each food sub-group. For ths reason, other dets that conform to the medan food subgroup patterns wll not necessarly acheve the DRIs. These results mean there s one det from amongst all possble dets that wll acheve them. In concluson, our optmal food formulaton derved from local foods acheved the nutrtonal goals for chldren aged months at a twofold ncrease of the observed food budget per chld. Also, the LP optmal formulatons met the recommended ntakes for 20 selected nutrents and acheved about 50% RDI for ron, whch was dentfed as one of the problem nutrents among rural Tanzanan chldren aged 6 11 months. Ths mples that, gven the avalable food choces, t s possble to develop optmal formulatons that can mprove mcronutrent recommendatons for rural chldren aged 6 23 months but at a cost whch s relatvely hgher than the observed household budget. The fndngs from the present study suggest the need for settng nterventons that can help the households to ncrease access to nutrent-dense foods that can overcome the dentfed mcronutrent gaps n Tanzana. Acknowledgments We thank the Nelson Mandela Afrcan Insttuton of Scence and Technology (NM-AIST) for provdng research grant to mplement the present study. We also thank Stephen A. Vost, Rena Engle-Stone, Mara E. Masawe and Chrstna N. Charles for sharng ther expertse and perspectves on the applcaton of LP n human nutrton and provdng feedback on early versons of ths manuscrpt. Dsclosure statement No potental conflct of nterest was reported by the authors. Fundng Ths work was supported by the Nelson Mandela Afrcan Insttuton of Scence and Technology (NM-AIST). References [1] Dewey KG, Vtta BS. Strateges for ensurng adequate nutrent ntake for nfants and young chldren durng the perod of complementary feedng: A&T Techncal Bref. Washngton (DC): Alve & Thrve-FHI360; [2] BMGF. Bll & Melnda Gates Foundaton (BMGF) nutrton strategy. Seattle (WA): Bll and Melnda Gates Foundaton; [3] Hlang LM, Fahmda U, Htet MK, et al. Local foodbased complementary feedng recommendatons developed by the lnear programmng approach to mprove the ntake of problem nutrents among monthold Myanmar chldren. Br J Nutr. 2015;116: [4] Black RE, Vctora CG, Walker SP, et al. Maternal and chld undernutrton and overweght n low-ncome and mddle-ncome countres. Lancet. 2013;382(9890): [5] Zmmermann MB, Hurrell RF. Nutrtonal ron defcency. Lancet. 2007;370: [6] FANTA. Valdaton of food-based recommendatons developed usng optfood for groups at nutrtonal rsk n the Western Hghlands of Guatemala. Washngton (DC): FHI 360/FANTA; 2015 Aug. p [7] FAO. Human nutrton n the developng world. FAO food and nutrton seres. Rome: Food and Agrculture Organzaton of the Unted Natons; [8] Osendarp SJM, Broersen B, van Lere MJ, et al. Complementary feedng dets made of local foods can be optmzed, but addtonal nterventons wll be needed to meet ron and znc requrements n 6- to

10 10 J. RAYMOND ET AL. 23-month-old chldren n low- and mddle-ncome countres. Food Nutr Bull. 2016; 37:1 27. [9] FAO/WHO. New busness models to help elmnate food and nutrton nsecurty: roadmap for exploraton. Rome: Food and Agrculture Organzaton of the Unted Natons (FAO); [10] Vtta BS, Benjamn M, Pres AM, et al. Infant and young chld feedng practces among chldren under 2 years of age and maternal exposure to nfant and young chld feedng messages and promotons n Dar es Salaam, Tanzana. Matern Chld Nutr. 2016;12: [11] TDHS. Tanzana demographc and health survey Dar es Salaam; Calverton (MD): Natonal Bureau of Statstcs; ICF Macro; p [12] Huffman SL, Pwoz EG, Vost SA, et al. Babes, soft drnks and snacks: A concern n low- and mddlencome countres? Matern Chld Nutr. 2014;10(4): [13] WHO. Global strategy for nfant and young chld feedng [Internet]. Geneva: World Health Organzaton (WHO); [cted 2016 Aug 28]. Avalable from: feedng_eng.pdf. [14] Parlesak A, Tetens I, Jensen JD, et al. Use of lnear programmng to develop cost- mnmzed nutrtonally adequate health promotng food baskets. PLoS One. 2016;11(10):1 19. [15] Vossenaar M, Knght FA, Tumlowcz A, et al. Contextspecfc complementary feedng recommendatons developed usng Optfood could mprove the dets of breast-fed nfants and young chldren from dverse lvelhood groups n northern Kenya. Publc Health Nutr [Internet]. 2016;1 13. [cted 2017 Mar 17]. Avalable from: %5Cn; abstract_s [16] Termote C, Raner J, Deptford A, et al. Assessng the potental of wld foods to reduce the cost of a nutrtonally adequate det: an example from eastern Barngo Dstrct, Kenya. Food Nutr Bull. 2014;35 (4): [17] Parlesak A, Geelhoed D, Robertson A. Toward the preventon of chldhood undernutrton: det dversty strateges usng locally produced food can overcome gaps n nutrent supply. Food Nutr Bull. 2014;35(2): [18] Ferguson E, Chege P, Kmywe J, et al. Znc, ron and calcum are major lmtng nutrents n the complementary dets of rural Kenyan chldren. Matern Chld Nutr. 2015;11(2015):6 20. [19] Ferguson EL, Darmon N, Fahmda U, et al. Desgn of optmal food-based complementary feedng recommendatons and dentfcaton of key problem nutrents usng goal programmng. J Nutr. 2006;136(9): [20] Brend A, Darmon N, Ferguson E, et al. Lnear programmng: a mathematcal tool for analyzng and optmzng chldren s dets durng the complementary feedng perod. J Pedatr Gastroenterol Nutr. 2003;36(1): [21] Brend A, Ferguson E, Darmon N. Local food prce analyss by lnear programmng: a new approach to assess the economc value of fortfed food supplements. Food Nutr Bull. 2001;22(2): [22] Tanzana Food and Nutrton Centre. Mnstry of health and socal welfare. Tanzana natonal nutrton survey. Dar es Salaam: Tanzana Food and Nutrton Centre (TFNC); [23] WHO. WHO chld growth standards: length/heght-forage, weght-for-age, weght-for-length, weght-forheght and body mass ndex-for-age: methods and development. Geneva: World Health Organzaton (WHO) Press; [24] Pan Amercan Health Organsaton (PAHO). ProPAN process for the promoton of chld feedng feld manual. 2nd ed. Washngton (DC): PAHO; [25] Santka O, Fahmda U, Ferguson EL. Development of food-based complementary feedng recommendatons for9-to11-month-oldper-urbanindonesannfants usng lnear programmng. J Nutr. 2009;139(1): [26] Skau JKH, Bunthang T, Chamnan C, et al. The use of lnear programmng to determne whether a formulated complementary food product can ensure adequate nutrents for 6- to 11-month-old Cambodan nfants. Am J Cln Nutr. 2013;99(1): [27] Lukmanj Z, Hertzmark E, Mlng N, et al. Tanzana food composton tables. 1st ed. Muhmbl Unversty of Health and Alled Scence (MUHAS),Tanzana Food and Nutrton Centre (TFNC) and Havard School of Publc Health (HSPH). Dar es Salaam: MUHAS- TFNC, HSPH; [28] USDA. USDA natonal nutrent database for standard reference release 28. Natonal Nutrent Database for Standard Reference. Washngton (DC); p , 13972, 17002, 17199, [29] WHO. Indcators for assessng nfant and young chld feedng practces: part I defntons. Geneva: World Health Organzaton (WHO); [30] USDA. USDA table of nutrent retenton factors, release 6 [Internet]. Washngton (DC): U.S. Department of Agrculture (USDA); [cted 2016 Aug 18]. Avalable from: retn6/retn06.pdf. [31] Okubo H, Sasak S, Murakam K, et al. Desgnng optmal food ntake patterns to acheve nutrtonal goals for Japanese adults through the use of lnear programmng optmzaton models. Nutr J. 2015;14:57. [32] Masset G, Monsvas P, Mallot M, et al. Det optmzaton methods can help translate detary gudelnes nto a cancer preventon food plan. J Nutr. 2009;139(8): [33] FAO/WHO. Vtamn and mneral requrements n human nutrton. 2nd ed. World Health Organzaton, edtor. Rome: WHO; [34] WHO. Complementary feedng of young chldren n developng countres: a revew of current scentfc knowledge. Geneva: World Health Organzaton (WHO); [35] FAO/WHO/UNU. Human energy requrements. Rome: (Food and Agrculture Organzaton of the Unted Natons (FAO)); 2004.

11 FOOD & NUTRITION RESEARCH 11 [36] FAO/WHO/UNU. Proten and amno acd requrements n human nutrton. World Health Organ Tech Rep Ser. 2007;935: [37] Health Canada. Canada s food gude. Ottawa (ON): Health Canada; [38] Jáuregu-Lobera I. Iron defcency and cogntve functons: revew. Neuropsychatr Ds Treat. 2014;10: [39] FANTA. Development of evdence-based detary recommendatons for chldren, pregnant women, and lactatng women lvng n the Western Hghlands of Guatemala. Washngton (DC): FHI 360/FANTA; [40] Nar R, Maseeh A. Vtamn D: the sunshne vtamn. J Pharmacol Pharmacother. 2012;3(2): [41] Gbbs M, Baley KB, Lander RD, et al. The adequacy of mcronutrent concentratons n manufactured complementary foods from low-ncome countres. J Food Compos Anal. 2011;24(3): [42] Gbson RS, Baley KB, Gbbs M, et al. A revew of phytate, ron, znc, and calcum concentratons n plant-based complementary foods used n low-ncome countres and mplcatons for boavalablty. Food Nutr Bull. 2010;31(2 SUPPL.):S134 S146. [43] Teucher B, Olvares M, Cor H. Enhancers of ron absorpton: ascorbc acd and other organc acds. Int J Vtam Nutr Res. 2004;74(6): [44] Hurrell R, Egl I. Iron boavalablty and detary reference values. Am J Cln Nutr. 2010;91(5):1461S 1467S. [45] Nagao A, Kotake-Nara E, Hase M. Effects of fats and ols on the boaccessblty of carotenods and vtamn E n vegetables. Bosc Botechnol Bochem. 2013;77 (5): [46] Merchant AT, Dehghan M. Food composton database development for between country comparsons. Nutr J. 2006;5:2.