Impact Evaluation of Food Fortification Programs

Chapter 32

Impact Evaluation of Food Fortification Programs: Review of Methodological Approaches Used and Opportunities to Strengthen Them Lynnette M. Neufeld and Valerie M. Friesen Global Alliance for Improved Nutrition (GAIN), Geneva, Switzerland

Chapter Outline 32.1 Introduction 32.2 Brief Overview of Findings From Fortification Program Impact Evaluations 32.3 Evaluation Designs Used to Assess Impact of Food Fortification Programs

305 306 309

32.1 INTRODUCTION The nutrition field benefits from a strong evidence base that is summarized in accessible overview papers, for example, the Lancet Maternal and Child Nutrition series 2008 (Bhutta et al., 2008; Black et al., 2008; Bryce et al., 2008; Morris et al., 2008; Victora et al., 2008) and 2013 (Bhutta et al., 2013; Black et al., 2013; Gillespie et al., 2013; Ruel et al., 2013) and many systematic reviews and meta-analyses. For many interventions, including food fortification, this evidence has been reviewed and synthesized in global guidelines (World Health Organization and Food and Agriculture Organization, 2006). The guideline process uses primarily meta-analysis of randomized controlled trials (RCTs) to assess the strength of the evidence and, taking into consideration certain programmatic considerations, the potential for impact of each intervention for specific nutrition outcomes (Pena-Rosas et al., 2012). The guidelines are meant to serve exactly as such, i.e., options for consideration for countries to choose in addressing nutritional problems in their countries. Moving from efficacy evidence (under controlled conditions) to effectiveness (under realistic program

32.4 Beyond Impact: Assessing Program Pathways and Evaluability 32.5 Implications for Improving Food Fortification Program Evaluations 32.6 Conclusions References

312 312 313 314

conditions), however, has a number of limitations and the evidence for program impact from rigorous impact evaluations is scarce for many nutrition interventions (Habicht and Pelto, 2014). Depending on the stage of the program and the specific questions being addressed, impact evaluations can serve formative or summative purposes. Formative evaluations are specifically designed to identify and address issues that will result in improved program design and/or implementation. Summative evaluations permit conclusions to be made related to the program for the purposes of accountability (e.g., whether specific targets or objectives were met, value for money, cost-effectiveness) and/ or further decision-making (e.g., continue, expand, change, or cancel a program) (Habicht et al., 1999). Much has been written on when and why to evaluate programs and we refer the readers to these resources for more detailed information related to formulating evaluation questions and choosing approaches for impact evaluation more generally (e.g., Habicht et al., 1999; White, 2009; The World Bank Group, 2016). The many chapters of this book make reference to the strength of the evidence for fortification of diverse food

Food Fortification in a Globalized World. DOI: https://doi.org/10.1016/B978-0-12-802861-2.00032-8 Copyright © 2018 Elsevier Inc. All rights reserved.

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vehicles and specific nutrients, and identify a number of strengths and weaknesses of the evidence base for efficacy and safety of fortification programs. Several of those chapters and previous reviews have called for more and better evidence of the impact of food fortification programs (i.e., effectiveness) on diverse outcomes and in diverse population groups (Das et al., 2013; Martorell et al., 2015; Victora et al., 2012), many of which note the need for better methodological approaches to do so. The primary objectives of this chapter are to review the methodologies that have been used to evaluate the impact of food fortification programs in populations, to discuss the strengths and limitations of these methodologies and resulting evidence, and based on these findings present specific recommendations by which the evidence for the effectiveness and safety of food fortification programs could be further strengthened.

32.2 BRIEF OVERVIEW OF FINDINGS FROM FORTIFICATION PROGRAM IMPACT EVALUATIONS Evidence confirms that food fortification programs can improve micronutrient status (as assessed by response in specific nutrient biomarkers) and a range of micronutrient deficiency-related functional outcomes, for example, reduction in neural tube defect and reduced goiter. These results are summarized by micronutrient in previous chapters in this book (see Section 6), and similarly referred to in relation to specific food vehicles (see Section 5). The

majority of evaluations have assessed effects in women of reproductive age, usually 15 (or 18) to 49 years, with some also including school-aged children and/or infants and young children (under 5 years of age). As you will see, Table 32.1 provides all references reviewed in footnotes for each nutrient/vehicle combination. Briefly, vitamin A fortification in various food vehicles (e.g., sugar, oil, maize flour, and wheat flour) consistently increases serum retinol levels in women and children. Iron fortification in a number of food vehicles (e.g., soy sauce, fish sauce, maize flour, wheat flour, bread, and sugar) shows fairly consistent positive impacts on serum ferritin and iron deficiency prevalence but mixed results on hemoglobin concentration and the prevalence of anemia. Evidence for the functional benefits of iron and vitamin A fortification are lacking. Iodine fortification, specifically salt iodization, consistently increases population-level urinary iodine levels and has a positive impact on reducing goiter prevalence in contexts where goiter was prevalent, although substantial time is required to eradicate goiter (Erdo˘gan et al., 2009; Jooste et al., 2000; Sooch et al., 1973). Few evaluations have included child development outcomes. Fortification of wheat and maize flour and/or bread with folic acid has had a positive impact on reducing neural tube defects in multiple countries where surveillance systems permit this assessment and concomitant changes in folate status have been noted in most. The contribution of fortified foods to dietary intake of vitamin D was assessed in national surveys in the United States (Fulgoni et al., 2011) and Europe (Flynn et al., 2009), but no program evaluations assessing

TABLE 32.1 Impact Evaluations of Large-Scale Food Fortification Interventions by Study Design Study Design

Nutrient

Food Vehicle(s)

Number of Studies

Key Results

Ecological

Iron

Wheat flour, maize flour

5a

Status: positive effect on iron status in all but one study; positive effect on hemoglobin concentration and prevalence of anemia in studies that assessed it (n 5 3)

Folic acid

Wheat flour, maize flour

12b

Status: positive effect on serum folate levels across studies

Salt

1c

Iodine Repeat crosssectional

Functional outcomes: positive effect on prevalence of neural tube defects in all but one study Status: positive effect on urinary iodine concentration

d

Status: positive effect on serum retinol levels across studies; positive effect on breast milk retinol concentrations in one study that assessed it

Vitamin A

Oil, sugar

2

Iron

Wheat flour, Maize flour

12e

Status: positive effect on iron status; mixed results (positive and no effect) across studies on hemoglobin concentration and prevalence of anemia

Iodine

Salt

5f

Status: mixed results (positive and no effect) across studies on urinary iodine concentration and goiter prevalence (Continued )

Impact Evaluation of Food Fortification Programs Chapter | 32

307

TABLE 32.1 (Continued) Study Design

Nutrient

Food Vehicle(s)

Number of Studies

Key Results

Cohort

Vitamin A

Oil, sugar

2g

Status: positive effect on serum and breast milk retinol concentrations in one study that assessed it; positive effect on vitamin A status (increased vitamin A stores, liver vitamin A concentrations, and plasma retinol concentrations) in one study that assessed it

Iron

Wheat flour, maize flour, soy sauce, rice

7h

Status: positive effect on iron status and hemoglobin concentration in 4 studies; mixed results (positive and no effect) across studies on prevalence of anemia

Folic acid

Wheat flour, maize flour

3i

Status: positive effects on serum folate status across studies

Iodine

Salt

2j

Status: no effect on thyroid autoimmunity in severely iodinedeficient children in one study Functional outcomes: reduction in prevalence of goiter in one study

Iodine

Salt

1k

Status: positive effect on urinary iodine concentration

Experimental

Functional outcomes: positive effect on prevalence of neural tube defects in one study that assessed it

Functional outcomes: no effect on cognitive and language development Iron

Sugar, soy sauce, fish sauce, wheat flour, bread

5l

Status: positive effect on iron status across studies; positive effect on hemoglobin levels and prevalence of anemia in two studies that assessed it

Vitamin A

Maize flour

1m

Status: no effect on serum retinol concentration Functional outcomes: increased body weight of children 1 3 years of age

Vitamin A

Wheat flour

1n

Status: positive effect on vitamin A status in children with marginal-to-low initial serum retinol concentrations

Vitamin D

Milk

2o

Status: positive effect on serum vitamin D concentration across studies

Vitamin D and calcium combined

Milk

4p

Status: mixed results (positive and no effect) across studies on serum vitamin D and calcium concentrations; positive effect on serum parathyroid hormone in 4 studies

a Martorell, R., Ascencio, M., Tacsan, L., Alfaro, T., Young, M.F., Addo, O.Y., et al., 2015. Effectiveness evaluation of the food fortification program of Costa Rica: impact on anemia prevalence and hemoglobin concentrations in women and children. Am. J. Clin. Nutr. 101, 210 217; Layrisse, M., Chaves, J.F., Bosch, V., Tropper, E., Bastardo, B., Gonzalez, E., 1996. Early response to the effect of iron fortification in the Venezuelan population. Am. J. Clin. Nutr. 64, 903 907; da Silva, C.L., Saunders, C., Szarfarc, S.C., Fujimori, E., da Veiga, G.V., 2012. Anaemia in pregnant women before and after the mandatory fortification of wheat and corn flours with iron. Public Health Nutr. 15, 1802 1809; Sato, A.P.S., Fujimori, E., Szarfarc, S.C., 2014. Hemoglobin curves during pregnancy before and after fortification of flours with iron. Rev. Esc. Enferm. USP 48, 409 414; Grimm, K.A., Sullivan, K.M., Alasfoor, D., Parvanta, I., Suleiman, A.J.M., Kaur, M., Al-Hatmi, F.O., Ruth, L.J., 2012. Iron-fortified wheat flour and iron deficiency among women. Food Nutr. Bull. 33, 180 185. b Abdollahi, Z., Elmadfa, I., Djazayery, A., Golalipour, M.J., Sadighi, J., Salehi, F., Sadeghian Sharif, S., 2011. Efficacy of flour fortification with folic acid in women of childbearing age in Iran. Ann. Nutr. Metab. 58, 188 196; Amarin, Z.O., Obeidat, A.Z., 2010. Effect of folic acid fortification on the incidence of neural tube defects. Paediatr. Perinat. Epidemiol. 24, 349 351; Sayed, A.-R., Bourne, D., Pattinson, R., Nixon, J., Henderson, B., 2008. Decline in the prevalence of neural tube defects following folic acid fortification and its cost-benefit in South Africa. Birt. Defects Res. A Clin. Mol. Teratol. 82, 211 216; Ricks, D.J., Rees, C.A., Osborn, K.A., Crookston, B.T., Leaver, K., Merrill, S.B., et al., 2012. Perus national folic acid fortification program and its effect on neural tube defects in Lima. Rev. Panam. Salud Pu´blica 32, 391 398; Corte´s, F., Mellado, C., Pardo, R.A., Villarroel, L.A., Hertrampf, E., 2012. Wheat flour fortification with folic acid: changes in neural tube defects rates in Chile. Am. J. Med. Genet. A 158, 1885 1890; Lo´pez-Camelo, J.S., Castilla, E.E., Orioli, I. M., INAGEMP (Instituto Nacional de Gene´tica Me´dica Populacional), ECLAMC (Estudio Colaborativo Latino Americano de Malformaciones Conge´nitas), 2010. Folic acid flour fortification: impact on the frequencies of 52 congenital anomaly types in three South American countries. Am. J. Med. Genet. A 152A, 2444 2458; Orioli, I.M., Lima do Nascimento, R., Lo´pez-Camelo, J.S., Castilla, E.E., 2011. Effects of folic acid fortification on spina bifida prevalence in Brazil. Birt. Def. Res. A Clin. Mol. Teratol. 91, 831 835; Chen, L.T., Rivera, M.A., 2004. The Costa Rican experience: reduction of neural tube defects following food fortification programs. Nutr Rev 62, S40-43; Hertrampf, E., Corte´s, F., 2008. National food-fortification program with folic acid in Chile. Food. Nutr. Bull. 29, S231 S237; Golalipour, M.J., Arabi, M., Ali Vakili, M., 2014. Impact of flour fortification with folic acid on the prevalence of neural tube defects in Northern Iran. J. Pediatr. Neurol. 12, 69 73; Alasfoor, D., Elsayed, M.K., Mohammed, A.J., 2010. Spina bifida and birth outcome before and after fortification of flour with iron and folic acid in Oman. East Mediterr. Health J. Rev. Sante´ Me´diterrane´e Orient. Al-Majallah Al-Sihh¯ıyah Li-Sharq Al-Mutawassit ˙ ˙ ˙ P., Crowley, M., ˙ 16, 533 538; De Wals, P., Tairou, F., Van Allen, M.I., Uh, S.-H., Lowry, R.B., Sibbald, B., Evans, J.A., Van den Hof, M.C., Zimmer, Fernandez, B., Lee, N.S., Niyonsenga, T., 2007. Reduction in neural-tube defects after folic acid fortification in Canada. N. Engl. J. Med. 357, 135 142.

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TABLE 32.1 (Continued) c Aga Khan University, 2001. National nutrition survey 2001. Planning Commission and Planning and Development Division, Government of Pakistan; Aga Khan University, 2011. National nutrition survey 2011. Planning Commission and Planning and Development Division, Government of Pakistan. d Sandjaja, Jusat, I., Jahari, A.B., Ifrad, Htet, M.K., Tilden, R.L., et al., 2015. Vitamin A-fortified cooking oil reduces vitamin A deficiency in infants, young children and women: results from a programme evaluation in Indonesia. Public Health Nutr. 18, 2511 2522; Arroyave, G., Mejia, L.A., Aguilar, J.R., 1981. The effect of vitamin A fortification of sugar on the serum vitamin A levels of preschool Guatemalan children: a longitudinal evaluation. Am. J. Clin. Nutr. 34, 41 49. e Kalimbira, A.A., MacDonald, C., Simpson, J.R., 2010. The impact of an integrated community-based micronutrient and health programme on anaemia in non-pregnant Malawian women. Public Health Nutr. 13, 1445 1452; Sadighi, J., Mohammad, K., Sheikholeslam, R., Amirkhani, M.A., Torabi, P., Salehi, F., Abdolahi, Z., 2009. Anaemia control: lessons from the flour fortification programme. Public Health 123, 794 799; Assunc¸a˜o, M.C.F., Santos, I.S., Barros, A. J.D., Gigante, D.P., Victora, C.G., 2007. Effect of iron fortification of flour on anemia in preschool children in Pelotas, Brazil. Rev. Sau´de Pu´blica 41, 539 548; Assunc¸a˜o, M.C., Santos, I.S., Barros, A.J., Gigante, D.P., Victora, C.G., 2012. Flour fortification with iron has no impact on anaemia in urban Brazilian children. Public Health Nutr. 15, 1796 1801; Layrisse, M., Garcı´a-Casal, M.N., Me´ndez-Castellano, H., Jime´nez, M., Olavarrı´a, H.C., Cha´vez, J.F., Gonza´lez, E., 2002. Impact of fortification of flours with iron to reduce the prevalence of anemia and iron deficiency among schoolchildren in Caracas, Venezuela: a follow-up. Food Nutr Bull 23, 384 389; Fujimori, E., Sato, A.P.S., Szarfarc, S.C., Veiga, G.V. da, Oliveira, V.A. de, Colli, C., Moreira-Arau´jo, R. S. dos R., Arruda, I.K.G. de, Uchimura, T.T., Brunken, G.S., others, 2011. Anemia in Brazilian pregnant women before and after flour fortification with iron. Rev. Saude Publica 45, 1027 1035; Costa, C.A., Machado, E.H., Colli, C., Latorre, W.C., Szarfarc, S.C., others, 2009. Anemia in pre-school children attending day care centers of Sa˜o Paulo: perspectives of the wheat and maize flour fortification. Nutr. Rev. Soc. Bras. Aliment. E Nutr. 34, 59 74; El Hamdouchi, A., El Kari, K., Rjimati, L., El Haloui, N., El Mzibri, M., Aguenaou, H., Mokhtar, N., 2010. Impact of flour fortification with elemental iron on the prevalence of anaemia among preschool children in Morocco. East. Mediterr. Health J. Rev. Sante´ Me´diterrane´e Orient Al-Majallah Al-Sihh¯ıyah Li-Sharq Al˙ ˙in˙ Fiji. 2010 Report. Mutawassit 16, 1148 1152; National Food and Nutrition Centre, 2012. Impact of iron fortified flour in child-bearing age (CBA) women ˙ National Food and Nutrition Centre, Suva; Micronutrient Initiative, 2008. Wheat flour fortification: a pilot project. Child in Need Institute, Department of Social Welfare in West Bengal State, Kolkata; Northrop-Clewes, C., Hund, L., Valadez, J, 2013. LC-LQAS survey report: Ministry of Health, Uzbekistan. National Flour Fortification Program. Ministry of Health, Tashkent; Nepali Technical Assistance Group, 2011. An impact study on small-scale fortification project in Lalitpur District Survey Period: February 2009 April 2011. Nepali Technical Assistance Group, Kathmandu. f Toma, A., Sava, M., Delia, C., Simescu, M., Tomescu, E., Coculescu, M., 2005. Universal salt iodization effects on endemic goiter in Arges county, ˘ ˘ Romania. Acta Endocrinol Buchar 1, 167; Erdogan, M.F., Demir, O¨., Emral, R., Kamel, A.N., Erdogan, G., 2009. More than a decade of iodine prophylaxis is needed to eradicate goiter among school age children in a moderately iodine-deficient region. Thyroid 19, 265 268.; Jooste, P.L., Weight, M.J., Lombard, C. J., 2000. Short-term effectiveness of mandatory iodization of table salt, at an elevated iodine concentration, on the iodine and goiter status of schoolchildren with endemic goiter. Am. J. Clin. Nutr. 71, 75 80; Sooch, S.S., Deo, M.G., Karmarkar, M.G., Kochupillai, N., Ramachandran, K., Ramalingaswami, V., 1973. Prevention of endemic goiter with iodized salt. Bull. World Health Organ. 49, 307; Mostafavi, H., 2005. Effect of adeequate salt iodization on the prevalence of goiter: A cross-sectional comparative study among school. Pak. J. Med. Sci. January March 21, 53 55. g Ribaya-Mercado, J.D., Solomons, N.W., Medrano, Y., Bulux, J., Dolnikowski, G.G., Russell, R.M., Wallace, C.B., 2004. Use of the deuterated-retinoldilution technique to monitor the vitamin A status of Nicaraguan schoolchildren 1 y after initiation of the Nicaraguan national program of sugar fortification with vitamin A. Am. J. Clin. Nutr. 80, 1291 1298; Sandjaja, Jusat, I., Jahari, A.B., Ifrad, Htet, M.K., Tilden, R.L., et al., 2015. Vitamin A-fortified cooking oil reduces vitamin A deficiency in infants, young children and women: results from a programme evaluation in Indonesia. Public Health Nutr. 18, 2511 2522. h Nestel, Nalubola, Sivakaneshan, Wickramasinghe, Atukorala, Wickramanayake, 2004. The use of iron-fortified wheat flour to reduce anemia among the estate population in Sri Lanka. Int. J. Vitam. Nutr. Res. 74, 35 51; Angeles-Agdeppa, I., Saises, M., Capanzana, M., Juneja, L.R., Sakaguchi, N., 2011. Pilotscale commercialization of iron-fortified rice: effects on anemia status. Food Nutr. Bull. 32, 3 12; Wang, B., Zhan, S., Sun, J., Lee, L., 2009. Social mobilization and social marketing to promote NaFeEDTA-fortified soya sauce in an iron-deficient population through a public-private partnership. Public Health Nutr. 12, 1; Huo, J., Sun, J., Huang, J., Li, W., Wang, L., Selenje, L., Gleason, G.R., Yu, X., 2012. Effectiveness of fortified flour for enhancement of vitamin and mineral intakes and nutrition status in northwest Chinese villages. Food Nutr. Bull. 33, 161 168; Huo, J.-S., Sun, J., Huang, J., Li, W.-X., Wang, L.-J., Selenje, L., Gleason, G.R., Yu, X.-D., 2011. The effectiveness of fortified flour on micronutrient status in rural female adults in China. Asia Pac. J. Clin. Nutr. 20, 118 124; Modjadji, S.E.P., Alberts, M., Mamabolo, R.L., 2008. Folate and iron status of South African non-pregnant rural women of childbearing age, before and after fortification of foods. South Afr. J. Clin. Nutr. 20, 89 95; Tazhibayev, S., Dolmatova, O., Ganiyeva, G., Khairov, K., Ospanova, F., Oyunchimeg, D., et al., 2008. Evaluation of the potential effectiveness of wheat flour and salt fortification programs in five Central Asian countries and Mongolia, 2002 2007. Food Nutr. Bull. 29, 255 265. i Abdollahi, Z., Elmadfa, I., Djazayery, A., Golalipour, M.J., Sadighi, J., Salehi, F., Sadeghian Sharif, S., 2011. Efficacy of flour fortification with folic acid in women of childbearing age in Iran. Ann. Nutr. Metab. 58, 188 196; Hertrampf, E., Corte´s, F., Erickson, J.D., Cayazzo, M., Freire, W., Bailey, L.B., et al., 2003. Consumption of folic acid fortified bread improves folate status in women of reproductive age in Chile. J. Nutr. 133, 3166 3169; Modjadji, S.E.P., Alberts, M., Mamabolo, R.L., 2008. Folate and iron status of South African non-pregnant rural women of childbearing age, before and after fortification of foods. South Afr. J. Clin. Nutr. 20, 89 95. j Zimmermann, M.B., Moretti, D., Chaouki, N., Torresani, T., 2003. Introduction of iodized salt to severely iodine-deficient children does not provoke thyroid autoimmunity: a one-year prospective trial in northern Morocco. Thyroid 13, 199 203; Sooch, S.S., Ramalingaswami, V., 1965. Preliminary report of an experiment in the Kangra valley for the prevention of Himalayan endemic goiter with iodized salt. Bull. World Health Organ. 32, 299. k Note this is the only large effectiveness trial of large-scale food fortification that was identified as part of this review. Aboud, F.E., Bougma, K., Lemma, T., Marquis, G.S., 2017. Evaluation of the effects of iodized salt on the mental development of preschool-aged children: a cluster randomized trial in northern Ethiopia. Matern. Child Nutr. 13 (2) [ePub ahead of print]. l Note that the included studies are small scale RCT, more analogous to efficacy trials than true program evaluations. de Paula, R.A.C., Fisberg, M., 2002. The use of sugar fortified with iron tris-glycinate chelate in the prevention of iron deficiency anemia in preschool children. Arch. Latinoam Nutr. 51, 54 59; Chen, J., Zhao, X., Zhang, X., Yin, S., Piao, J., Huo, J., Yu, B., Qu, N., Lu, Q., Wang, S., 2005. Studies on the effectiveness of NaFeEDTA-fortified soy sauce in controlling iron deficiency: a population-based intervention trial. Food Nutr. Bull. 26, 177 186; Van Thuy, P., Berger, J., Nakanishi, Y., Khan, N.C., Lynch, S., Dixon, P., 2005. The use of NaFeEDTA-fortified fish sauce is an effective tool for controlling iron deficiency in women of childbearing age in rural Vietnam. J. Nutr. 135, 2596 2601; Sadighi, J., Sheikholeslam, R., Mohammad, K., Pouraram, H., Abdollahi, Z., Samadpour, K., Kolahdooz, F., Naghavi, M., 2008. Flour fortification with iron: a mid-term evaluation. Public Health 122, 313 321; Viteri, F.E., A´lvarez, E., Batres, R., Torun, B., Pineda, O., Mejı´a, L.A., Sylvi, J., 1995. Fortification of sugar with iron sodium ethylenediaminotetraacetate (FeNaEDTA) improves iron status in semirural Guatemalan populations. Am. J. Clin. Nutr. 61, 1153 1163. m Note that the included studies are small scale RCT, more analogous to efficacy trials than true program evaluations. Nesamvuni, A.E., Vorster, H.H., Margetts, B.M., Kruger, A., 2005. Fortification of maize meal improved the nutritional status of 1 3-year-old African children. Public Health Nutr. 8, 461 467. n Note that the included studies are small scale RCT, more analogous to efficacy trials than true program evaluations. Solon, F.S., Klemm, R.D., Sanchez, L., Darnton-Hill, I., Craft, N.E., Christian, P., West, K.P., 2000. Efficacy of a vitamin A-fortified wheat-flour bun on the vitamin A status of Filipino schoolchildren. Am. J. Clin. Nutr. 72, 738 744. o Note that the included studies are small scale RCT, more analogous to efficacy trials than true program evaluations. Khadgawat, R., Marwaha, R.K., Garg, M.K., Ramot, R., Oberoi, A.K., Sreenivas, V., Gahlot, M., Mehan, N., Mathur, P., Gupta, N., 2013. Impact of vitamin D fortified milk supplementation on vitamin D status of healthy school children aged 10-14 years. Osteoporos Int. 24, 2335 2343; Rich-Edwards, J.W., Ganmaa, D., Kleinman, K., Sumberzul,

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Impact Evaluation of Food Fortification Programs Chapter | 32

309

TABLE 32.1 (Continued) N., Holick, M.F., Lkhagvasuren, T., Dulguun, B., Burke, A., Frazier, A.L., 2011. Randomized trial of fortified milk and supplements to raise 25hydroxyvitamin D concentrations in school children in Mongolia. Am. J. Clin. Nutr. 94, 578 584. p Note that the included studies are small scale RCT, more analogous to efficacy trials than true program evaluations. Xueqin, D.U., Zhu, K., Trube, A., Zhang, Q., Ma, G., Hu, X., Fraser, D.R., Greenfield, H., 2004. School-milk intervention trial enhances growth and bone mineral accretion in Chinese girls aged 10 12 years in Beijing. Br. J. Nutr. 92, 159 168; Zhu, K., Du, X., Cowell, C.T., Greenfield, H., Blades, B., Dobbins, T.A., Zhang, Q., Fraser, D.R., 2005. Effects of school milk intervention on cortical bone accretion and indicators relevant to bone metabolism in Chinese girls aged 10 12 y in Beijing. Am. J. Clin. Nutr. 81, 1168 1175; Kruger, M.C., Ha, P.C., Todd, J.M., Kuhn-Sherlock, B., Schollum, L.M., Ma, J., Qin, G., Lau, E., 2012. High-calcium, vitamin D fortified milk is effective in improving bone turnover markers and vitamin D status in healthy postmenopausal Chinese women. Eur. J. Clin. Nutr. 66, 856 861; Kruger, M.C., Schollum, L.M., Kuhn-Sherlock, B., Hestiantoro, A., Wijanto, P., Li-Yu, J., Agdeppa, I., Todd, J.M., Eastell, R., 2010. The effect of a fortified milk drink on vitamin D status and bone turnover in post-menopausal women from South East Asia. Bone 46, 759 767.

impact on status or function were identified. Evidence of fortification program impact is lacking for other nutrients, for example, calcium and zinc, and for other food vehicles for which efficacy has been shown, such as double fortified salt (iron and iodine). The lack of evidence of impact of fortification programs on functional outcomes beyond goiter and NTDs is notable yet not surprising given the complexity to measure some functional outcomes, for example child development (see, for example, Aboud et al., 2017). Whether change in status is sufficient for impact assessment of food fortification programs will depend on many factors including the purpose for which the evaluation is being conducted, the strength of the existing evidence for changes in functional outcomes in response to changes in micronutrient status, as well as resource and time constraints in the evaluation. We found few program impact evaluations that purposefully assessed indicators of risk or potential adverse effects. Although generally considered safe, some concerns have been raised about the safety of fortification of commonly consumed foods for some nutrients. For example, high intakes of folic acid may affect vitamin B12 status and thus may increase risk in those already at risk, such as the elderly (see Rosenberg, Chapter 24). Concerns have been also been raised about iron, a nutrient essential to humans but also many harmful microorganisms, including malaria (see Hurrell, Chapter 20). One study in Morocco did purposefully assess and found no risk of adverse outcomes (thyroid autoimmunity) in severely iodine-deficient children 1 year after implementation of salt iodization in the country (Zimmermann et al., 2003). These examples demonstrate concerns related to the safety of food fortification in specific subgroups of the population based on other risks associated with age or health and nutritional status. Safety could also be a concern for most nutrients if programs lead to excessive intakes in populations, for example, where consumption of the nutrient is already adequate from dietary sources, other programs provide the same nutrients, or fortification levels are set too high.

Such risks can be minimized with proper program design, monitoring, and evaluation. The example of sugar fortification in Guatemala (see Tanumihardjo, Chapter 24) clearly demonstrates that even when programs have been designed appropriately, program evaluation should regularly include risk assessment to determine whether the underlying assumptions that guided the need for and design of the program hold, particularly deficiency rates and dietary intake patterns of the food vehicle.

32.3 EVALUATION DESIGNS USED TO ASSESS IMPACT OF FOOD FORTIFICATION PROGRAMS An overview of available impact evaluation studies for food fortification, classified by the study methodology used is shown in Table 32.1. Studies were compiled from an extensive review of available electronic reference libraries (i.e., PubMed), and cross-referenced from existing and forthcoming systematic reviews, and from other chapters in this book. Unpublished evaluations, those in unindexed journals, and those published in languages other than English, French, Spanish, or Portuguese may have been missed. The majority of the evidence for impact of food fortification programs comes from observational evaluations, specifically ecological, cross-sectional, and cohort designs. There have been a number of very small-scale randomized trials but only one large randomized controlled effectiveness trial was identified. This section provides an overview of a number of strengths and limitations of each methodology for evaluating impact of food fortification programs, drawing on examples from published reports. A number of evaluations of fortification programs have used a retrospective ecological design, particularly for assessing impact of folic acid fortification (12 studies) and iron fortification (five studies). Ecological studies use existing population-based data to assess trends pre- and post-fortification or can be used to assess relationships

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between exposure and outcome by examining populationlevel data rather than individual-level data at a single point in time (Aschengrau and Seage, 2013). The main advantage of such designs is that they are low cost as they use existing data (for example, nutritional surveillance, national surveys, or hospital records). As such, ecological evaluation designs are summative and rarely provide the type of information needed for formative purposes, i.e., program improvement. Like other observational studies, analyzing time trends in such data can help strengthen the quality of the evidence related to the impact of food fortification programs. For example, trends in the prevalence of anemia from existing household surveys have been analyzed in Costa Rica to assess changes before and after the implementation of the food fortification program (Martorell et al., 2015, Chapter 35). Cross-sectional studies assess the prevalence of the outcome of interest in a population at a specific point in time (Aschengrau and Seage, 2013). A large proportion of the existing evidence for food fortification comes from studies using repeat cross-sectional designs (i.e., cross-sectional surveys implemented pre- and post-fortification), including 12 studies of iron fortification, five of iodine fortification, and two of vitamin A fortification. For example, Sandjaja et al. used both repeat crosssectional surveys and a cohort study to evaluate the oil fortification program on vitamin A status of women of reproductive age and children less than 6 months of age in Indonesia (Sandjaja et al., 2015). Cohort studies follow subjects over time and are able to directly measure exposure levels and incidence of outcomes (Aschengrau and Seage, 2013). This design may meet more causal criteria (see below) than an ecological or cross-sectional design; however the disadvantage is that they are often expensive and time-consuming to implement, as they require ongoing data collection. Cohort designs have also been used to assess effects of iron in a number of food vehicles, folic acid in wheat and maize flour, and iodine in salt. RCTs have long been considered the gold standard in epidemiology to demonstrate causality of an intervention as they minimize confounding factors and bias that may arise in observational designs (Aschengrau and Seage, 2013). In the context of a population-based program such as food fortification however, this type of experimental design is rarely feasible, as it requires being able to manipulate the exposure to food fortification among different groups over time. A number of small RCTs have been used to evaluate the impact of food fortification, but are more analogous to a research trial (where researchers assure quality of implementation) than a true program evaluation. We found only one randomized controlled program evaluation that assessed the impact of

salt iodization in Ethiopia on status, physical growth, and mental development of preschool-aged children using a cluster randomized design (Aboud et al., 2017). The evaluation took advantage of the gradual rollout of the fortification program and randomly allocated villages to receive iodized salt early (intervention group) or later (control group). This was a unique opportunity that required careful planning, foresight, and collaboration from government and salt distributors alike to permit the planned program rollout in the country and the careful design and implementation of the evaluation around this. Although highly desirable in terms of assessing change in diverse outcomes and attribution of these to fortification, this type of evaluation would not be feasible in contexts with existing programs or where government and other stakeholders are not willing to manage planned program rollout. The primary weakness of all observational study designs, and thus the majority of evidence for effectiveness of food fortification programs, is the lack of basis for attribution of any observed changes to the program (i.e., no counterfactual that permits assessment of what would have happened in the population in the absence of the program). Paying close attention to epidemiological criteria for causal attribution, specifically consistency and strength of association, dose response, biological plausibility, and temporality (Potischman and Weed, 1999) can substantially increase the strength of the evidence. For ecological studies, this has limitations unless additional data on potential external factors that would influence results are available and can be adjusted for in multivariate analyses, which has been done in some cases (Martorell et al., 2015; Sato et al., 2014). Information on potential confounding factors can be collected as part of prospective evaluations, and has been reported for some (see, for example, Sandjaja et al., 2015 and Nestel et al., 2004) but not others (see, for example, Tazhibayev et al., 2008 and Modjadji et al., 2008). Evaluations that purposefully assess causal criteria, regardless of study design, could be considered analogous to plausibility evaluation, in the terminology proposed by Habicht et al. (1999). “Plausibility designs” (i.e., those that attempt to adjust for potential confounding factors) have a number of advantages in terms of feasibility and cost compared to “probability designs” (i.e., randomized program evaluations). They are also advantageous compared to “adequacy designs” (i.e., comparison of outcomes with preset objectives) in terms of potential to attribute changes to the program. Thus, many of the program evaluations to date for food fortification have largely been fit-to-purpose in that they have utilized feasible and, in many cases, relatively low-cost methodologies that provide some potential to address causal criteria. For

Impact Evaluation of Food Fortification Programs Chapter | 32

the purposes of this chapter, we have summarized in Table 32.2 the overall direction of the evidence of impact for fortification programs and provided a qualitative (subjective) assessment of the extent to which the causal criteria for each have been met. Based on an overview of the evidence for an impact of food fortification on vitamin A, iron, and folate status, most causal criteria are met and thus it is highly plausible that observed results are attributable to those programs. Similarly, the reduced prevalence of neural tube defects (folic acid) and goiter (iodine) can likely be attributed to food fortification programs, based on the assessment of causal criteria. The evidence for all other nutrients and

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outcomes is weak due to lack of evaluations, poor study design, and/or inconsistency among published studies. The causal criteria that are weakest for most nutrient/outcome combinations are dose response and biological plausibility, criteria that can be assessed only by including a number of factors across the pathway to impact for fortification. Some evaluations (for example, Sandjaja et al., 2015) have included measures of exposure of the population studied to fortified foods, in this case contribution of vitamin A from fortified foods to total vitamin A intake, but did not go on to perform dose response analyses. For many other evaluations, such data is not reported and assumed to be unavailable. An assessment of biological

TABLE 32.2 Direction and Strength of the Evidence for Casual Inferences From Impact Evaluations of Food Fortification on Status and Function for Diverse Nutrientsa Nutrient

Outcome

Direction of Association

Strength and Consistency of Evidenceb

DoseResponsec

Biological Plausibilityd

Temporalitye

Vitamin A

Statusf

Positive

Yes

No

Yes (in one study)

Yes

Functional outcomes

(Not assessed)

Statusf

Positive

Yes

No

Yes (in some studies)

Yes

Hemoglobin and anemia

Inconsistent

No

No

No

Yes

Functional outcomes

Inconsistent (child development)

No

No

No

Yes

Statusf

Positive

Yes

No

Yes

Yes

Functional outcomes

Positive (neural tube defects)

Yes

No

Yes

Yes

Statusf

Positive

Yes

No

Yes

Yes

Functional outcomes

Positive (goiter)

Yes

No

Yes

Yes

No effect (child growth and/or development)

No

No

No

Yes

Statusf

Positive

Yes (but few studies)

No

No

Yes

Functional outcomes

Not assessed

Iron

Folic acid

Iodine

Vitamin D

a For the purpose of this paper we classify each based on a subjective assessment of the extent to which epidemiological causal criteria (Potischman and Weed, 1999) are met. b Strength and consistency of the evidence were assessed together, based on whether the majority of studies (arbitrarily defined as .75%) for any given nutrient/outcome combination reported statistically significant results for the outcome. c Dose response was based on whether studies assessed the magnitude of impact in relation to level of exposure to the program, based on assessment of coverage and/or reported utilization of the fortified food in the population studied. d Plausibility was assessed based on whether the direction of any effect could be explained considering the quality of program implementation across a pathway to impact assessment (see Fig. 32.1). e Temporality was classified as met if the majority (arbitrarily defined as .75%) of the studies for any given nutrient/outcome combination were based on time trend analysis for ecological studies, repeat cross-sectional studies, longitudinal cohort or randomized effectiveness trials. f Including significant change in biomarker of nutrient status and/or prevalence of deficiency as assessed based on such biomarkers.

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plausibility for an attributable effect of food fortification would also require assessment of key variables that quantify need (i.e., deficiency and/or inadequate intake of nutrients in the diet) and impact potential (i.e., bioavailable form of the nutrient, appropriate food vehicle consumed regularly and in appropriate quantities by those in need, and actual fortification of the food at recommended levels). Including such information routinely in program evaluations would substantially improve their utility for program improvement purposes.

32.4 BEYOND IMPACT: ASSESSING PROGRAM PATHWAYS AND EVALUABILITY Despite being conceptually simple, food fortification programs require a number of conditions to be met to be impactful. These conditions are clearly articulated in a simple impact pathway put forth by Martorell et al. (2015), as you will see in Fig. 32.1. Specifically, programs should be implemented in populations where there is need for the intervention (i.e., evidence of deficiency and/or inadequate nutrient intakes). The right foods should be chosen that will reach those in need, and those

foods must actually be fortified at appropriate levels and with appropriate (i.e., bioavailable) forms of the nutrient. Finally, those in need must consume fortified foods in sufficient quantity to have a public health impact. Evidence to demonstrate these factors is absent from many fortification program evaluations. This limits the ability to assess biological plausibility for any demonstrated association. It also limits the ability to explain null findings, specifically whether the program is not impactful or whether it is not adequately implemented to reach its potential impact. A number of the evaluations with null findings have reported program design (e.g., low fortificant content, poor bioavailability of the fortificant, or low consumption of food in the population) as potential explanations for null findings (see, for example, Assunc¸a˜o et al., 2012; Ricks et al., 2012). An additional challenge for fortification program evaluation, as with impact evaluations of many nutrition programs, is the relatively short duration of most studies compared to the relatively long time needed to correct functional outcomes. Short evaluation duration has been cited as a potential explanation for null findings for functional outcomes in a number of program evaluations (see, for example, Aboud et al., 2017; Jooste et al., 2000; Mostafavi, 2005). Unfortunately, without assessing all critical components of fortification programs, as shown in Fig. 32.1, such explanations for null findings are at best speculative.

32.5 IMPLICATIONS FOR IMPROVING FOOD FORTIFICATION PROGRAM EVALUATIONS

FIGURE 32.1 Program impact pathway for mass fortification programs. Reproduced with permission from Martorell, R., Ascencio, M., Tacsan, L., Alfaro, T., Young, M.F., Addo, O.Y., et al., 2015. Effectiveness evaluation of the food fortification program of Costa Rica: impact on anemia prevalence and hemoglobin concentrations in women and children. Am. J. Clin. Nutr. 101, 210 217.

The challenges of program evaluation highlighted here are not new and many frameworks and approaches have been developed to strengthen the quality of evaluations in timing, scope, and design. Since the mid-1970s, evaluation literature has sought to find approaches that would improve the quality and utility of evaluations such as program evaluability and evaluation readiness (Cohen et al., 1985). Both seek to increase the value and utility of program evaluations for decision-making by ensuring that programs are evaluated only when: (1) program implementers/managers are willing to collaborate in the evaluation, for example, by providing information, being interviewed, and being prepared to accept the evaluation results; and (2) appropriate data exists and/or can be generated to assess sufficient relevant elements. Evaluation readiness adds the additional component of ensuring that clear program objectives and understanding of how the program is anticipated to work have been articulated, whether that be through a logic model or comprehensive results framework (Cohen et al., 1985) or an impact pathway (Habicht and Pelto, 2014).

Impact Evaluation of Food Fortification Programs Chapter | 32

More recently, “theory-based evaluation” has been put forth as the most appropriate methodology to ensure relevance, quality, utility, and value of impact evaluations (White, 2009). A theory-based evaluation approach maps the impact pathway or causal chain, from program inputs and activities through outputs and outcomes to impact, then purposefully tests the underlying assumptions as part of the evaluation. Unfortunately, the use of impact pathways (or theory-based evaluation) is still the exception rather than the norm and this review shows the same to be true for food fortification evaluation. One notable exception is the evaluation of fortification of multiple vehicles in Costa Rica (Martorell et al., 2015). The evaluation used a clear impact pathway to guide the design of the evaluations and to seek available information from diverse sources to strengthen the ability to address the extent to which each step in the pathway was met. National micronutrient surveys and other studies implemented before fortification were used to establish that there was a need for fortification (i.e., high prevalence of iron deficiency and anemia) and program monitoring data were used to confirm that the appropriate type of fortificant had been used, and that food was in effect fortified (i.e., compliance of industry). Thus despite using an ecological design, one which might normally be criticized for the low potential for causal attribution, the evaluation was able to make strong conclusions related to the likely impact of the program. The case of Costa Rica provides an excellent example of using impact pathways to strengthen the quality and utility of summative (retrospective) evaluations, but this approach is equally or possibly more important to use for formative (prospective) evaluations, i.e., those with the purpose of improving program design and implementation. In fact, developing and using impact pathways to guide the design of programs and not waiting to identify design and/or implementation issues during evaluation is urgently needed in food fortification. These challenges were clearly highlighted in a recent publication of a series of surveys implemented to assess coverage of food fortification programs (Aaron et al., 2017; Knowles et al., 2017). The surveys identified a number of cases where food fortification had low potential for impact due to choice of a fortifiable food vehicle with low coverage and/or utilization in the population, and/or poor compliance with fortification regulations. Ensuring that programs are designed with high potential for impact and implemented with high quality should be prerequisites as part of program design and implementation. These conditions (i.e., high enough coverage and utilization, and adequate fortification of the food vehicle) should be confirmed before attempting to measure impact. High coverage is a prerequisite for impact of any intervention or program and many factors, including

313

availability, accessibility, and acceptability of products/ services, may affect program coverage (Tanahashi, 1978). Currently, information on program coverage and the factors that limit or facilitate it is rarely available in nutrition programs, and in particular in food fortification (International Food Policy Research Institute, 2016; Sight & Life, 2014). Coverage estimates can be used to directly assess the potential of programs for impact and to identify solutions to improving potential during program implementation prior to assessing impact on biochemical or functional outcomes. The need for the generation and use of this evidence for program decision-making on food fortification has been specifically highlighted in the global nutrition community in recent years (International Food Policy Research Institute, 2016; Neufeld et al., 2016; Sight & Life, 2015, 2014). Standardizing the use of impact pathways to guide evaluation would go far to improve the quality of evidence for food fortification. Six elements of good practice and some concrete mechanisms to ensure their implementation have been well articulated (White, 2009). This begins by mapping the impact pathway (also referred to as causal chain or program theory). A clear understanding of program context must be brought in from the outset, as well as ensuring the variability within that context (e.g., geographical, cultural, economic differences in deficiency prevalence and fortifiable food consumption patterns) and the extent to which these may influence program potential is anticipated. Mixed methods and rigorous analysis of data are critical, as is ensuring the choice of best fit-to-purpose methodology with credible counterfactual. For food fortification, like other untargeted interventions, there are clearly limitations in the extent to which this counterfactual can be a true control group. Working within that limitation and ensuring rigorous implementation of the best feasible methodology for evaluation would greatly strengthen evidence for food fortification.

32.6 CONCLUSIONS Evidence for the impact of food fortification with some nutrients based on biochemical indicators of status is relatively consistent for vitamin A, iodine, folate, and iron status. Evidence is weak for functional outcomes other than neural tube defects and goiter, and for improving status of nutrients others than those listed above. While limited in potential for direct causal inferences, the use of observational designs for impact evaluation of food fortification programs is often unavoidable and some studies have used methods that permit a reasonable assessment of causal criteria. Using clear impact pathways to guide evaluations, regardless of the study design, is essential to ensure quality, relevance, and value of evidence. Bringing

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the same theory into program design from the outset can help avoid erroneous assumptions related to the need and potential for impact, and aid in identifying implementation challenges that may limit potential. Prospective evaluations should therefore be prioritized over retrospective evaluations, as a means to ensure that such challenges can be identified and acted on in a timely fashion. The majority of the studies reviewed in this chapter have evaluated mandatory fortification programs (i.e., fortification of food vehicles that are mandated and regulated by government authorities). As the number and coverage of mandatory and voluntary (i.e., the addition of nutrients to specific foods at the will of industry) fortification programs increases in many countries, it will become imperative to evaluate the impact and ongoing relevance of fortification programs and to include assessment of the risks of high intakes in subgroups of the population that may be consuming multiple fortified foods.

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