It has been our experience to find that the stools from all babies receiving breast milk give an acid or neutral reaction when tested with litmus and that the stools from bottle-fed babies receiving simple cow's milk mixtures may be acid, neutral or alkaline when so tested. It has also been our experience to note that excoriation of the buttocks may often be associated with the elimination of acid stools.
The cause of the acid stools from bottle-fed babies has been a question of much theory and conjecture and up to the present time has not received any satisfactory explanation. It is our belief that the reaction of the stools may be dependent, to a great extent, on the chemical composition of the food ingested; that the composition of the food influences the bacterial growth within the intestines and determines the predominance of bacterial types; and that the type of
ALFRED W. BOSWORTH, H. KENNETH WILDER, MARGUERITE E. BLANCHARD, ELSIE W. BROWN, MARION F. McCANN. STUDIES OF INFANT FEEDING. XVII. A BACTERIOCHEMICAL STUDY OF THE ACID STOOLS EXCRETED BY BREAST-FED AND BOTTLE-FED INFANTS. Am J Dis Child. 1922;23(4):323–337. doi:10.1001/archpedi.1922.01910400043004