A parent emailed me via our iPhone App and asked if her childs constipation, which started as he was transitioning from formula to whole milk, could be a sign of lactose intolerance. She is concerned because her son is now having very hard stools.
Actually, lactose intolerance does not typically cause constipation, but conversely causes abdominal pain and often loose stools or diarrhea. In the case of this 1 year old child who suddenly is having hard stools, it may seem to be caused by the switch from formula to whole milk, but is probably coincidental.
It is routinely recommended that parents stop giving a child a bottle and formula at 1 year, which often results in a toddler drinking less milk (recommended amount is about 16 ounces /day) and therefore they are getting less fluid which may result in harder stools. This is also the age that childrens diets are changing as they are self feeding and often eat a lot of carbohydrates (breads, noodles, rice etc) and fewer fruits and vegetables, even when offered as they become pickier eaters.
All told this often leads to bouts of constipation that can be managed with the addition of more fluids as well as clever ideas such as apple prune juice, bite sized prunes (often can be sold as raisins to a young child) and even with milk of magnesia if necessary. (see older posts on constipation)
Lactose intolerance is defined as the inability to digest lactose which is a sugar found in milk and milk products. It is due to a deficiency in the enzyme lactase, which is produced by cells lining the small intestine. Lactose intolerance is uncommon in young children and is typically not seen before the age of 2 -3 years. It is more common in older children and teens who may complain of abdominal pain, cramping, gas, bloating and diarrhea after ingesting dairy products. In most cases lactose intolerance is diagnosed on clinical history alone, and if suspected is managed by eliminating dairy products to see if the symptoms improve.
In many cases even children with a lactase deficiency may tolerate some lactose in their diet such as a scoop of ice cream, or milk on their cereal, but only experience symptoms when they have too much milk. Fortunately, there are products, such as lactose free milk, which will provide a child with the necessary vitamin D and calcium which is so important during childhood. Dietary supplements should also be used in children who do not drink milk in order that they meet their daily calcium and vitamin D requirements. Lastly, lactose intolerance is different than a milk allergy which is fairly uncommon and is due to an allergy to the proteins in milk, not the lactose. True milk allergy usually presents in early infancy.