Evaluating food-based programmes for their reduction of vitamin A deficiency and its consequences

Food-based approaches, using foods naturally rich in micronutrients, are one strategy for combating micronutrient deficiencies. They can have both a direct impact on nutritional status and health by changing the production, preparation, and consumption of foods, and an indirect impact by changing associated aspects such as income, expenditure, and empowerment of women. This combination of a direct and an indirect impact, each of which can also be confounded by other factors, complicates the evaluation of the impact of food-based approaches. In order to develop food-based approaches into a sound and well-recognized strategy for combating micronutrient deficiencies, with appropriate appreciation of their possible impact as well as of their limitations, food-based programmes have to be evaluated for their impact on nutritional status and health. This paper suggests ways to do this by using a conceptual framework for designing the programme and evaluating its impact, studying the relationship between the consumption of particular foods and nutritional status, and assessing the contribution of a food-based programme to reducing the risk of vitamin A deficiency relative to other programmes. One of the main conclusions is that intervention studies can be used to study particular relationships identified by the conceptual framework, such as the relationship between increased consumption of leafy vegetables and vitamin A status, but that specific evaluations are necessary to assess the impact of a particular food-based programme, because of the many confounding factors that are difficult to take into account in a smaller-scale intervention study.