Nutritional Assessment in a Rural Area of Bolivia. A Study of Zinc and Iron Deficiencies and Bioavailability

University dissertation from Media-Tryck

Abstract: While originally, protein-energy deficiency was considered the main factor of malnutrition, it is now understood that micronutrient deficiencies play a fundamental role in a variety of health and disease outcomes. Zinc and iron deficiencies are still highly prevalent in low-income countries, whereas insufficient intakes and diets with low mineral absorption are the major causes. Sustainable and feasible dietary strategies are needed to alleviate micronutrient deficiencies.
The present research was designed to evaluate the nutritional status of adults and children from a rural tropical area in Bolivia. The evaluation was made taking into account: nutrient intakes assessed by our new developed and validated dietary assessment method, anthropometric measurements and biochemical indicators of trace element status. With a focus on elucidating the causes of existing deficiencies of zinc and iron, the content of the mineral absorption inhibitor phytate was evaluated in the main foods and in the dietary intake of the studied populations; the presence of parasitic diseases and their effect on the trace element status was also evaluated. Furthermore, the inclusion of a fermented food in the basal tropical diet was carried out in order to improve the absorption of zinc in the diet, it was evaluated in Wistar rats and compared with zinc-supplemented diets.
The developed method for dietary assessment is based on digital photographs and it was satisfactorily validated against a reference method. Results of the dietary intake of children and adults showed the dietary patterns, mainly based on plant-foods: the main source of energy was carbohydrates 63-71%E from starchy tubers, cereals, and legumes, fat 16-23%E from oil or tallow, and protein 13-14%E from plant-foods and a small contribution of animal-food sources. In adults, 7% (women) were underweight. Zinc deficiency was found in 15% of controls and 29% of patients with leishmaniasis. The nutritional status of children was more diminished, indicating 37% as being stunted, 17% wasted and 17% underweight, 87% zinc deficient and 66% iron deficient. The zinc deficiencies were negatively associated to the high levels of phytate in the diet, indicated by the correlations between serum zinc and phytate:zinc molar ratios; for adults -0.410 and children -0.458 (P<0.01). Parasitic infections; leishmaniasis and intestinal parasites have also been shown to have a negative effect on zinc and iron status. Finally, the inclusion of fermented cassava, in the basal plant-based diet was shown to have a positive effect increasing the zinc apparent absorption of the diet from 16.5 to 40.2%, which is comparable to results obtained when the diet was supplemented with zinc.
In conclusion, this research presents a suitable and reliable method for assessing the dietary intake in rural populations in developing countries. The dietary patterns of a rural population from Bolivia are presented, shedding light on the existence of zinc and iron deficiencies indicated to be caused by high levels of phytates in their diet and by the presence of parasitic diseases. Additionally, fermentation is presented as an efficient dietary strategy for the improvement of zinc absorption in the plant-based diet of the studied population; it may represent a better nutritional and economical alternative than the use of supplements, adequate for rural areas in developing countries, where the diets are limited in animal-food sources.