2023
Abstract
Achieving a balanced and diverse diet remains a challenge for many people, contributing to an ongoing burden of micronutrient de-ficiencies, particularly in low-income settings. Fortification or dietary diversification are common food-based approaches. We conducted a scoping review to: 1) find evidence on whether combined food–based strategies are more effective than single strategies, and 2) understand how strategies implemented together could complement each other to achieve optimal nutritional impact on populations. Peer-reviewed articles selected (n ¼ 21) included interventions or observational studies (n ¼ 13) and reviews (n ¼ 8). We found little evidence of an added nutritional impact. On the other hand, it is apparent that fortification and dietary diversification target different types of settings (urban compared with rural) and foods (that is, low priced compared with highly priced). Further research is needed to understand the complementarity of these approaches and establish evidence of the effectiveness of combined strategies to foster policy adoption.
Keywords: food diversity, fortification, biofortification, hidden hunger, nutritional impact, integrated food-based strategies
Introduction
Micronutrient deficiencies continue to pose a major global public health problem, particularly in low- and middle-income countries (LMICs), contributing to impaired linear growth of children, reduced immunocompetence, and suboptimal cogni-tive development, thereby impeding the development of both individuals and societies. A recent study estimates that 1 in 2 preschool aged children, and 2 in 3 women of reproductive age are deficient in 1 vitamins or minerals [1]. Despite data gaps, global estimates based on the analysis of existing national sur-veys reveal that vitamin A deficiency in children has improved in East Asia but remains high in South Asia and Africa [2]. The extent of zinc deficiency remains uncertain due to limited data, but it is estimated to affect >20% of children living in LMICs [3]. Universal iodization of salt has significantly reduced iodine deficiency, but there are 25 countries in which mild to moderate forms of iodine deficiency remain prevalent [4]. In addition, folate deficiency is still a major issue, linked to an estimated 260,100 neural tube defects (including ~175,000 stillbirths and neonatal deaths) [5]. Anemia continues to affect an estimated 41.6% of children and 32.6% of women of repro-ductive age globally, with data suggesting iron deficiency to be an important, but not the only cause [6,7].
Efforts to combat the burden of these deficiencies over many decades have included a range of nutrition-specific and nutrition-sensitive interventions [8] which can be broadly grouped into four categories: micronutrient supplementation; fortification A. Bechoff et al.
(including biofortification); dietary diversification; and public health and disease control (Figure 1). Fortification and dietary diversification fall under food-based strategies whereas the other two strategies are part of a health approach. These strategies were first described at the International Conference on Nutrition, organized by the FAO and WHO in December 1992 [9]. Bio-fortification—referred to as micronutrient-enhanced crops by the European Commission—was not developed at this time, but was included in later guidelines [10]. Food-based approaches to improve micronutrient status focus on the consumption of foods that are either naturally rich in micronutrients or have been enriched through fortification [11].
We distinguish different forms of fortification depending on the process and the stage at which micronutrients are added. With industrial fortification, home fortification or food-to-food fortification, micronutrients are added at the site of processing or point of use (consumption), whereas in biofortification, micronutrient content is increased during cultivation, generally using conventional breeding techniques or micronutrient-enhanced fertilizers. Dietary diversification involves increasing the range of foods consumed to better meet the requirements for macro- and micronutrient intake. Although food fortification focuses on increasing the content of one or more specific nutri-ents in staple foods, dietary diversification typically relates to the introduction or more frequent consumption of nonstaple foods in existing diets.
Industrial fortification and biofortification have gained most attention in nutritional policies, but concerns have been raised about whether promoting fortification as a standalone approach could divert policy makers from other strategies such as supporting diverse and healthy diets [12,13]. Fortification strategies could lead to a limited impact on micronutrient deficiencies, because food fortification is often with a limited number of micronutrients (for example, iodized salt or vitamin A fortified oils), and there are constraints to the amount of micronutrients in biofortified foods that can be achieved through breeding. Likewise, there are chal-lenges linked to the implementation of dietary diversification as a single strategy, as foods naturally rich in micronutrients are often unaffordable for the poorer segments of societies, and linear pro-gramming analyses suggest that local foods may be unable to meet nutrient requirements for some population groups in some settings [14–16]. Moreover, producers in rural settings often face various constraints to produce diversified commodities, and the effects of production diversity on smallholder farming households’ diets varies between settings [17,18].
To accelerate progress in improving micronutrient status of populations globally, policy recommendations have called for integrating food-based approaches [6,9]. Despite a body of evi-dence to support the impact on nutritional status of food-based strategies taken separately, there is a knowledge gap about the effectiveness of those actions used in combination [19]. We hy-pothesize that combining food fortification with diversification of diets would lead to improved nutritional outcomes compared with strategies focusing on either approach alone. The objective of this article is to evaluate the combination, and potential complementarity, of fortification and dietary diversification to improve the micronutrient status of populations.