Malabsorção de lactose do adulto. Prevalencia na população sulina. Aspectos geneticos e evolutivos do polimorfismo da atividade da lactose

AUTOR(ES)
DATA DE PUBLICAÇÃO

1990

RESUMO

A lactose loading test was applied to seventy healthy adults, well nourished, from Southern Brazil (48 caucasoids and 22 negroids) with no secondary lactase deficiency. The distribution of the examined individuals according to race and to maximum blood glucose rise after the lactose loading test showed an antimode at the interval bet ween 14 and 17 mg% and another antimode between 33 and 36 mg%. It seems, therefore, that a maximum blood glucose rise of less than 17 mg% after the lactose loading test should indicate lactose malabsorption. On the basis of this criterion, adult type lactose malabsorption was manifested by 18 caucasoids (37,5%) and 15 negroids (6B,l8Ji). It was not demonstrated significant association among adult type lactase malabsorption and milk consumption or history of milk intolerance. However, lactose malabsorption was associated with lactose intolerance. Moreover, it seems attractive to suppose that a maximum blood glucose rise between 17 and 36 mg% would indicate heterozygous lactose absorbers, while a maximum blood glucose rise of 36 mg% or more would indicate homozygous lactose absorbers. There is an indication drawn from population genetics which favors this hypothesis. The variability of adult lactase activity represents a genetic polymorph ism. The mechanism by which this polymorphism evolved from the ubiquity of lactose malabsorption in early human populations is controversial. The two most accepted hypothesis, the culture historical and the calcium absorption, were critically analysed and refuted. I propose an alternative hypothesis which seems better suited to explain the evolution of this polymorphism.

ASSUNTO(S)

leite como alimento lactose

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