Efectos diferenciales del condicionamiento aversivo a sabores sobre la ingesta de sacarosa y estevia / Differential effects of conditioned taste aversion on sucrose and stevia intake

Resumen La asociación entre un estímulo alimentario y una sensación de malestar produce una aversión alimentaria, procedimiento denominado condicionamiento aversivo a sabores (CAS). Dado que no existen evidencias claras acerca de los efectos de este procedimiento sobre el consumo de endulzantes, el propósito de este estudio fue examinar la efectividad del CAS para disminuir el consumo de dos endulzantes naturales. Se trabajó con 30 ratas Wistar, distribuidas en tres grupos. En la fase 1 los grupos fueron expuestos a alimento y cada uno a una solución distinta: agua + sacarosa (G1), agua + estevia (G2) y agua sin endulzar (GC). En la fase 2 los grupos experimentales recibieron una inyección intraperitoneal de cloruro de litio. En la fase 3 los grupos retornaron a las condiciones de la primera fase. Después del CAS, G1 y G2 disminuyeron significativamente su consumo de bebida, sin embargo fue mayor al registrado en GC. Los resultados se discuten en función de la asociación entre el sabor y el contenido energético, lo que permite establecer nuevas directrices en el estudio del consumo de endulzantes. Se concluye que los procedimientos que producen aversión condicionada podrían resultar eficaces en el control de algunas conductas alimentarias alteradas.

Abstract The association between a food stimulus and a feeling of discomfort produces a food aversion; this procedure is called aversive taste conditioning (ATC). Since there is no clear evidence about the effects of this procedure on the consumption of sweeteners, the purpose of this study was to examine the effectiveness of ATC to decrease the consumption of two natural sweeteners. Thirty Wistar rats were divided into three groups. In phase 1 all groups were exposed to free food access and each group to a different solution: water + sucrose (G1), water + stevia (G2) and unsweetened water (CG). In phase 2 the experimental groups received an intraperitoneal injection of lithium chloride. In phase 3 the groups returned to the conditions of the first phase. After the ATC, the G1 and G2 significantly decreased their beverage consumption, although it was higher than the consumption of CG. The results are discussed in terms of the association between flavor and energy content, which allows establishing new guidelines in the study of the consumption of sweeteners. It is concluded that procedures such as ATC are effective in the control of some disordered eating behaviors.

Percepção de sabores em pessoas normais / Flavor perception in healthy volunteers

Introdução: percepção do sabor do alimento ingerido pode ter importante papel na proteção do sistema digestivo. Objetivo: avaliar a capacidade de percepção dos sabores amargo, azedo, doce e neutro em pessoas normais. Método: foram estudados 46 indivíduos saudáveis, 22 homens e 24 mulheres com idades entre 23 e 71 anos, média de 45 anos. Cada sujeito deglutiu, em sequência aleatória, 5 mL de bolos líquidos com 4 sabores: amargo (chá de Peumus boldus), azedo (suco de limão diluído), doce (sacarose diluída) e neutro (água) na temperatura ambiente. Após cada deglutição, os participantes foram questionados sobre o sabor do líquido deglutido. Resultados: não houve diferença na frequência de acertos na identificação dos sabores (amargo: 80%, azedo: 85%, neutro: 89% e doce: 89%). Não houve diferenças relacionadas ao gênero na identificação dos sabores. Cinco indivíduos (25%) entre os jovens (23-39 anos) não identificaram o sabor azedo, o que aconteceu em 2 (8%) dos mais idosos (40-71 anos). Vinte e sete (59%) indivíduos identificaram todos os sabores, 13 (28%) não identificaram um sabor, 5 (11%) não identificaram dois sabores e um indivíduo (2%) não identificou 3 sabores. Conclusão: entre 80% e 90% dos sujeitos da população estudada foram capazes de identificar o gosto do líquido que deglutiu, mas 41% não identificou pelo menos um sabor entre os quatro avaliados.

Introduction: perception of the swallowed bolus taste may have an important role in the protection of the digestive tract. Objective: to evaluate the perception of bitter, sour, sweet and neutral tastes of a liquid bolus in normal individuals. Method: we studied 46 healthy subjects, 22 men and 24 women aged 23 to 71 years, mean 45 years. Each subject swallowed in a random sequence, 5 mL of a liquid bolus with four flavors: bitter (Peumus Boldus tea), sour (limon juice diluted), sweet (sucrose diluted) and neutral (water) all at room temperature. After each swallow the participants were asked about the taste of the liquid swallowed. Results: there was no difference in the frequency of the correct identification of flavors (bitter: 80%, sour: 85%, neutral: 89% and sweet: 89%). There was no gender difference in the flavor identification. Five (25%) of the younger subjects (20-39 years) did not identify the sour taste, what happen in 2 (8%) of older subjects (40-71 years). Twenty-seven (59%) individuals identified all flavors, 13 (28%) did not identify one flavor, 5 (11%) did not identify two flavors and only one individual (2%) did not identify three flavors. Conclusion: between 80% to 90% of the population studied was able to identify the taste of the liquid they swallowed, but 41% did not identify at least one flavor.

Context-switch Effect Produced by the Ambiguity of the Meaning of a Cue / Efecto de cambio de contexto producido por la ambigüedad del significado de la clave

One experiment analyzed whether context dependency of a flavor-illness association depends on the extinction of a different flavor-illness association in rats. There were two sessions per day, one in context A and the other session in context B. A half of the rats were allowed to drink distilled water within context B, while the other half of the group spent the same amount of time in context B without access to water. In context A, half of the subjects received conditioning and extinction of flavor X, while the other half did not received extinction. Then conditioning of flavor Y was conducted for all rats in context A. Finally, testing of Y was conducted in context A for half of the rats, while the other half received the test in context B. Results shown that extinction of flavor X affected the recovery of subsequently acquired information about flavor Y regardless the treatment received in context B. This data is consistent with Atttentional Theory of Context Processing.

Un experimento analizó si la dependencia contextual de una asociación sabor - enfermedad depende de la extinción de una asociación sabor - enfermedad distinta en ratas. Se realizaron dos sesiones diariamente, una en el contexto A y la otra en el contexto B. Una mitad del grupo ratas bebieron agua destilada en el contexto B, mientras que la otra mitad del grupo se colocó por el mismo tiempo en el contexto A sin beber nada. La mitad de las ratas recibieron condicionamiento y extinción de un sabor X en el contexto A, mientras que la otra mitad no recibió extinción. Luego todas las ratas fueron condicionadas con el sabor Y en el contexto A. Por ultimo, se hizo la prueba de Y en el contexto A para la mitad del grupo, y en el contexto B para la otra mitad. Los resultados mostraron que la extinción del sabor X afectó la recuperación del favor Y sin importer si el tratamiento se hizo en el contexto B. Estos datos son consistentes con la Teoría Atencional de Procesamiento del Contexto.