Breast‐milk amylase activities during 18 months of lactation in mothers from rural Zaire

Abstract

Breast milk collected from mothers in rural Zaire was analyzed in order to determine if differences in amylase activities are maintained throughout a prolonged lactational period that could potentially make a valuable contribution to the digestion of cereal-based weaning foods in young and poorly nourished children. Breast milk samples were collected 9 times during 18 months of lactation from 12 mothers who were 20-53 years old with parity of 1-6. They were of poor nutritional status (mean standard deviation weight-for-height = 84 (12)% of the WHO median and 4 subjects were malnourished as judged by serum albumin levels less than 32 g/l. Solid foods were introduced to infants in this community at 2-5 months of age. Amylase activities were measured in skimmed breast milk by the hydrolysis of maltotetraose at 37 degrees Celsius using a centrifugal analyzer. The range of activities showed a decrease during the first months of lactation. Expressing the results relative to protein concentrations reduced but did not abolish the decrease in activity with stage of lactation. Breast milk amylase activities varied widely between individuals by 10- to 100-fold; and depending on the stage of lactation differentials observed in early lactation were maintained throughout the 18-month period. Analysis of variance demonstrated that the differences in amylase activities between mothers and with stage of lactation were highly significant (effect of the individual (df = 1177): F = 13.3 p < 0.001; effect of stage of lactation (df = 777): F = 3.3 p < 0.01). No associations were found between an individuals breast milk amylase activity at any stage of lactation and her age parity nutritional status or breast milk protein concentration. Considerable long-term differences occur in the amylase activity of breast milk between mothers although breast milk contains significant amounts of amylase throughout lactation. The daily ingestion of amylase by breast-fed infants therefore will also vary substantially between individuals.