Regardless of the type of infant feeding, the first signs of malnutrition appear with a slightly foaming green-colored stool; also the green frothy stool in the baby can be due to intestinal microbiota disturbance and the prevalence of pathogenic microbes in it.
In other cases, the reasons for the foamy stool in the baby are associated with genetically conditioned fermentopathies, as well as congenital intolerance to milk sugar (lactose), cow's milk proteins (lactoglobulins), gluten (wheat, rye, oats and barley) gluten.
According to the pediatricians, frequent bloating, colic and foamy stool in breastfed babies immediately leads to suspicion that the child has hypolactasia or secondary malabsorption of lactose (insufficient digestion), which is usually called lactase deficiency in children or allergy to lactose. It should be noted that the complete congenital absence of lactase, inherited as an autosomal recessive trait, is rarely diagnosed.
More often, the pathogenesis of a disturbed metabolism of lactose is associated with a decreased expression or activity of lactase (glycoside hydrolase), an intestinal enzyme that is localized in membranes of the epithelial mucosal enterocytes of the small bowel (microvilli) of the small intestine.
In this type of fermentopathy flatulence and yellow frothy stools appear as a result of the fact that in case of insufficient expression of lactase, the carbohydrate of breast milk lactose [β-D-galactopyranosyl (1-4) -D-glucose] is not practically digested, that is, it does not split in the small intestine, digestible monosaccharides, D-glucose and D-galactose, are digested by the body.
Studies have shown that partial deficiency of lactase due to immaturity of the intestine has premature babies, but it is impossible to increase the activity of this enzyme, since it refers to non-insulinable enzymes. However, as soon as the lactose digesting bacterium-symbionts Lactobacillus and Bifidobacterium appears in the intestine of the infant, its stool is normalized.
In addition, a decrease in lactase expression in infants may occur due to an excessively high level of the thyroid hormone thyroxine, although in all newborns the levels of triiodothyronine and thyroxine necessary for the development of the central nervous system are slightly increased.
Malabsorption of lactose is fraught with infectious enteritis and inflammation of the intestine of any etiology, medications (in particular antibiotics), congenital small bowel syndrome in an infant. Presence of any of these factors can be caused by a frothy stool with blood in the baby.
When there is a frothy stool in a breastfed on mixed feeding, the cause may be not only lactase deficiency or the reaction of the intestine to a new complementary product, but also an allergic reaction to gluten proteins of cereal crops - celiac disease. Its pathogenesis is the abnormal immune response of the body and the production of autoantibodies to gluten or gliadin, which leads to an inflammatory reaction in the small intestine epithelium with atrophy of a part of the microvilli.
Loss of appetite, bloating, chronic diarrhea and frothy stool in infants with artificial feeding can also be due to gluten intolerance.
The yellow frothy stool in the baby, and sometimes the liquid frothy stool with blood can be the result of milk allergy in children, more precisely, whey proteins of cow's milk.
And in the case of hereditary intolerance to sucrose, caused by a lack of intestinal enzymes of isomaltase and alpha-glucosidase, a watery frothy stool appears in the infants, whose diet contains sugar-containing milk formulas, fruit purees and juices.