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Liquid, frothy stools in the infant yellow, green color
Medical expert of the article
Last reviewed: 04.07.2025
Pediatricians always pay attention to any changes in the nature of feces in infants as the main indicator of the state of the digestive system, on the correct functioning of which the child's development depends. Therefore, the appearance of such a symptom as foamy stool in an infant requires finding out its causes and taking appropriate measures.
Epidemiology
In domestic pediatrics, statistics on enzymatic pathologies among infants are practically non-existent. But specialists in neonatal endocrinology emphasize that congenital lactase deficiency is extremely rare, and much more common diagnoses are: glucose-galactose malabsorption (lactase deficiency) and milk protein allergy.
Premature babies born at 28 weeks of gestation have minimally low levels of lactase in their intestines. But almost 40% of babies born at 34 weeks have significantly higher levels of lactase activity, making it possible to breastfeed them.
It is estimated that nearly 4 billion people worldwide have lactose malabsorption, but symptoms of lactose intolerance rarely develop in children under six years of age.
Intolerance to cow's milk lactoglobulins occurs in 2-5% of infants in the first three months of life.
Causes frothy stools in a baby
Regardless of the type of infant feeding, the first signs of malnutrition are slightly foamy, greenish stool; green foamy stool in infants can also be due to a violation of the intestinal microbiota and the predominance of pathogenic microbes in it.
In other cases, the causes of foamy stools in infants are associated with genetically determined enzyme deficiencies, as well as congenital intolerance to milk sugar (lactose), cow's milk proteins (lactoglobulins), and cereal gluten (wheat, rye, oats, and barley) - gluten.
According to pediatricians, frequent bloating, colic, and foamy stools in a breastfed infant immediately raise suspicions that the child has hypolactasia or secondary lactose malabsorption (insufficient digestion), which is commonly called lactase deficiency in children or lactose allergy. It should be noted that complete congenital absence of lactase, inherited as an autosomal recessive trait, is diagnosed extremely rarely.
Most often, the pathogenesis of lactose metabolism disorders is associated with reduced expression or activity of lactase (glycoside hydrolase), an intestinal enzyme that is localized in the membranes of enterocytes of the mucous epithelium of the brush border (microvilli) of the small intestine.
With this type of fermentopathy, flatulence and yellow foamy stool in infants appear as a result of the fact that, with insufficient expression of lactase, the carbohydrate in breast milk, lactose [β-D-galactopyranosyl-(1-4)-D-glucose], is practically not digested, that is, it is not broken down in the small intestine into monosaccharides that are absorbed by the body - D-glucose and D-galactose.
Studies have shown that premature babies have partial lactase deficiency due to intestinal immaturity, but it is impossible to increase the activity of this enzyme, since it is a non-individual enzyme. However, as soon as a sufficient number of lactose-digesting symbiotic bacteria Lactobacillus and Bifidobacterium appear in the infant's intestines, their stool normalizes.
In addition, decreased lactase expression in infants may occur due to excessively high levels of the thyroid hormone thyroxine, although all newborns have slightly elevated levels of triiodothyronine and thyroxine, which are necessary for the development of the central nervous system.
Lactose malabsorption can be caused by infectious enteritis and intestinal inflammation of any etiology, medications (especially antibiotics), and congenital short bowel syndrome in infants. The presence of any of these factors can cause foamy stools with blood in infants.
When foamy stools are observed in a mixed-fed infant, the cause may be not only lactase deficiency or an intestinal reaction to a new complementary food product, but also an allergic reaction to gluten proteins in cereals - celiac disease. Its pathogenesis consists of an abnormal immune response of the body and the production of autoantibodies to gluten or gliadin, which leads to an inflammatory reaction in the epithelium of the small intestine with atrophy of part of the microvilli.
Loss of appetite, bloating, chronic diarrhea and foamy stools in a formula-fed baby can also be caused by gluten intolerance.
Yellow foamy stool in infants, and sometimes liquid foamy stool with blood, can be the result of an allergy to milk in children, more precisely, to the whey proteins of cow's milk.
And in the case of hereditary sucrose intolerance, caused by a deficiency of the intestinal enzymes isomaltase and alpha-glucosidase, watery foamy stools appear in infants whose diet includes sugar-containing milk formulas, fruit purees and juices.
Risk factors
The likelihood of foamy stools in infants increases if:
- the mother does not have enough breast milk;
- the child has intestinal microflora disorders;
- the baby was born prematurely (premature babies, in addition to having an immature intestine, are distinguished by the fact that they suckle poorly at the breast and often suffer from malnutrition);
- parents introduce complementary foods incorrectly;
- there is a family history of enzyme pathologies;
- the child has a family history of celiac disease (first-degree blood relatives);
- The child's blood has elevated levels of thyroid hormones.
Complications and consequences
The inability of the child's intestines to digest lactose not only slows down the growth of beneficial bifidobacteria and the formation of healthy microbiota, but also reduces the intake of galactose, which is part of lactose and necessary for the formation of glycolipids in cell membranes.
Complications of milk intolerance - if proper nutrition is not prescribed in time - lead to damage to the mucous membrane of the large intestine, chronic diarrhea and delayed development of children.
Nutritional deficiencies, B vitamin deficiencies, anemia and growth retardation are possible consequences of gluten protein allergy.
Diagnostics frothy stools in a baby
In pediatrics, diagnosis of foamy stool in infants is based on the anamnesis and complaints of the parents, examination of the child, assessment of the level of his development and dynamics of weight gain.
The following tests are taken:
- stool analysis (microbiological, for carbohydrate content, for pH level);
- general blood test;
- blood test for thyroid hormones (T3 and T4);
- Blood ELISA for immunoglobulin IgE (to cow's milk lactoglobulins) and antibodies to gliadin (IgA).
Differential diagnosis
Differential diagnostics is necessary to accurately determine the nature of the existing pathology – enzymatic or immune.
Who to contact?
Treatment frothy stools in a baby
The only treatment for foamy stool in infants with the above metabolic pathologies is a diet depending on the etiology: lactose-free, dairy-free, sucrose-free, gluten-free.
Read also: What to do if your child is lactose intolerant?
Probiotics recommended by pediatricians only help in cases of intestinal microflora disorders.
Prevention
To date, there are no preventive measures to prevent the development of lactose malabsorption, congenital intolerance to milk proteins or gluten.
Forecast
Foamy stool in infants returns to normal if restrictions are observed that are introduced into the child's nutrition system. In the case of celiac disease, these restrictions must be observed throughout life.
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