A breastfeeding mother often keeps a close eye on her baby’s bowel movements to help keep track of the baby’s milk intake. While most bowel movements from breastfed babies do not have a strong smell, an acidic smell from your baby’s stool could indicate a dietary sensitivity, or a more serious medical condition. Fortunately, most cases of acidic-smelling stools in breastfed babies are preventable and treatable with simple changes in your diet, or your baby’s.
Unusual-smelling stools in your baby’s diaper often result from dietary causes. Sensitivity to lactose is a cause of foul-smelling stools in a breastfed baby, as the cow’s-milk proteins you consume are passed to your baby through your breast milk. Feeding your baby solids such as dairy products, or foods containing nuts, eggs or gluten also trigger sensitivities in some babies, leading to foul odors and other changes in bowel movements. Less commonly, medical problems with your baby’s digestive system such as malabsorption, Crohn’s disease or cystic fibrosis lead to acidic-smelling stools.
A slightly acidic smell, such as that of sour milk, is the normal and expected odor of a breastfed baby’s stool, explains the North Dakota Department of Health website. For most nursing mothers, there is no reason to reduce the amount of foods you enjoy or eliminate anything in your usual diet. According to the Kelly Mom website, while cow’s milk proteins are the most common cause of food sensitivities and related foul-smelling stools, very few babies have actual milk allergies or intolerance. Alleriges are also highly variable; foods that irritate one baby’s belly do not necessarily cause problems for another nursing baby, explains the website.
If your pediatrician suspects your baby’s acidic stool is due to an intolerance or allergy to a food you're eating, an elimination diet on your part is often enough to correct the condition. According to the Kelly Mom website, your body might need up to two weeks to eliminate all the trigger proteins, and your baby’s body may need another week or two on top of that to rid him of the offending proteins. Acidic-smelling stools caused by intestinal infections require no specific treatment, unless your baby develops severe diarrhea and vomiting. In that case, an oral rehydration or electrolyte solution, in addition to your breast milk, treats dehydration symptoms related to your baby’s illness.
You do not need to stop breastfeeding your baby if his stools develop an acidic or foul-smelling odor. Keep a diary of foods you eat, or foods you give your baby, and his bowel movements, to pinpoint trigger foods. Then you can eliminate them from your diet. Adding one new food to your baby’s diet, every four to five days, and giving solids and single-ingredient foods, makes it easier to identify foods that irritate your baby’s tummy.