UBC Theses and Dissertations
Impact of vitamin A nutrified soybean oil on the vitamin A status of a selected community in Southern Brazil Fradera, Ursula G.
Previous studies have revealed that marginal vitamin A deficiency poses a common public health problem among poor population groups in Southern Brazil. Nutrification programs in Guatemala (sugar) and in the Philippines (MSG) have resulted in improved vitamin A status, accompanied by positive changes in the anthropometric and general health status. Accordingly, the main purpose of the present pilot study was to evaluate the potential impact of vitamin A nutrified soybean oil on the vitamin A status of a selected community in Southern Brazil. Additional objectives were to assess the vitamin A and general nutritional status of the participants. The study was conducted in Vila Piratininga, a shanty town located on the periphery of Ribeirao Preto, a typical agricultural town in the sugarcane and coffee region of the state of Sao Paulo. Fifty-seven families were randomly assigned to experimental and control groups and were provided for four months with soybean oil that was either fortified with vitamin A (92,000 IU of retinyl palmitate per one litre can) or unfortified. To evaluate the impact of nutrification, biochemical and dietary indicators of vitamin A status were assessed before and after the supplementation. Dietary intake data were obtained from the female head of each household using the 24 hour recall method. Additional information on the usual consumption pattern of vitamin A containing foods was collected at the start of the study, using a food frequency questionnaire. Plasma retinol and (β-carotene levels of all subjects were analysed. Anthropometric measurements served as additional indicator of general nutritional status. Furthermore, throughout the intervention mothers, were questioned about the incidence of diarrhea and respiratory diseases among their children. Results from the serum vitamin A analysis at baseline confirmed that vitamin A deficiency was a public health problem among this low income population. Forty percent (control group) and 59% (experimental group) of preschool children, the most vulnerable age group, had low or deficient serum retinol concentrations. Plasma (β -carotene and dietary data showed that the intake of vitamin A and carotenoids from the rice and bean based diet was very low. The consumption of nutrified soybean oil increased the estimated daily vitamin A intake of the experimental group by 500% (p<0.001). However, this improved intake was not reflected in plasma retinol levels. Plasma vitamin A values of supplemented individuals dropped significantly (p<0.001) during the intervention, indicating that vitamin A nutrified soybean oil was not effective in improving their vitamin A status. The lack of response to supplementation in this study does not necessarily suggest that soybean oil is not a feasible vehicle for vitamin A nutrification. The fortified oil was well accepted by the participants and used daily for the preparation of meals; eventual losses of vitamin A during cooking and/or storage can be regarded as minimal. Therefore, this negative impact is more likely due to other factors. In populations with marginal vitamin A deficiency, as in Vila. Piratininga, the limitations of serum retinol levels as an accurate indicator of vitamin A body reserves should be appreciated. In addition, morbidity data revealed that infections were common among participating children. Infections may have impaired vitamin A absorption and utilization, increased requirements and consequently interfered with a successful nutrification. This was the first study to use vegetable oil as the carrier for vitamin A. Although this trial did not result in the expected impact on vitamin A status of the present study population, the feasibility of this vehicle should be further studied. In future investigations, the relative dose response test (RDR), which is a more sensitive index of vitamin A body reserves, should be performed on a subsample of the whole study population. Furthermore, concurrent reduction in the magnitude and severity of precipitating or contributary risk factors such as parasitic infestation, diarrheal and respiratory infections could improve the outcome of a nutrification intervention.