Lactose is the sugar (carbohydrate) found in milk and milk products. It is present in the milk of all mammals but is not found anywhere else in nature. Human breast milk contains around seven per cent lactose. Infant formula contains a similar amount.
Lactose is a disaccharide (which means it's a combination of 2 sugars). In its original form as a disaccharide it's too large to be absorbed by the body, so it needs to be broken down into glucose and galactose, which are monosaccarides (single sugars), by the digestive enzyme 'lactase'. Glucose and galactose can then be absorbed into the blood stream and used by the body.
Lactose is important in our diet. It aids the absorption of calcium and phosphorus and is thought to support the growth of friendly bacteria needed to fight undesirable organisms and promote health in the human intestine.
Galactose, a simple sugar that comes from the breakdown of lactose, is vital to a healthy brain and nerve tissues. Galactose can be found in some foods, but for a baby milk containing lactose may be his/her only source of galactose during what is an important stage of brain development. The effect of long term use of lactose-free formulas (which does not provide galactose) on babies' brain development is yet to be fully studied.
Glucose, the other simple sugar that bonds with galactose to form lactose in milk, provides a major source or energy (calories) in an infant's diet. Glucose is essential for growth, energy and for cell development. Without glucose in the diet a child will start to use body fat as a source of energy and will lose weight. If deprived of dietary glucose for a long period, the child will not survive. Glucose is found in most foods including lactose-free milk.
Lactose overload, also called 'functional lactase insufficiency', is a temporary problem related to immaturity of an infant's digestive system. An overload of lactose occurs when a baby's digestive system is unable to produce sufficient quantities of the digestive enzyme lactase to break down all of the lactose received.
Around two thirds of healthy, thriving breastfed babies experience some degree of lactose overload in the early months of life due to foremilk-hindmilk imbalance. This generally occurs when a nursing mother has an oversupply of breast milk and switches sides too soon. As a result the baby receives large volumes of low fat foremilk that is disproportionate to the amount of hindmilk received.
Formula feed babies can also experience gastrointestinal symptoms associated with lactose overload as a result of receiving excessive volumes of milk in the situation of overfeeding. The reasons for a baby to overfeed can be varied - see our article on hungry baby for examples.
Symptoms are often mistakenly diagnosed as colic, lactose intolerance or milk allergy or intolerance. Because lactose overload is associated with an oversupply of milk and/or overfeeding, spitting up is increased and a diagnosis of gastro-esophageal reflux is common.
When all is running smoothly, lactose is broken down into simple sugars, glucose and galactose, in the small intestine by the digestive enzyme lactase. Glucose and galactose can then be absorbed from the small intestines into the blood supply and used by the body.
When a nursing mother has an oversupply of breast milk (which is common in the early weeks of breastfeeding) switches sides too soon, or feeds baby frequently alternating breasts at each feeding, this can result in a baby receiving large volumes of foremilk (which has a low fat content). The lower the fat content of the milk the faster it will empty from the baby's stomach and the faster it will travel through the intestinal tract. Breastfeeds which provide a disproportionate amount of foremilk compared to hindmilk may pass through a baby's small intestines too quickly to provide sufficient time for all the lactose to be broken down.
Overfeeding is a common problem for bottle-fed babies in the newborn period (birth to three months) because newborns have limited ability to control the flow of milk though an artificial nipple or indicate when they have had enough owing to the presence of their sucking reflex. A baby's digestive system can become overloaded when it receives excessive amounts of milk from large volume feeds or frequent feeding patterns. The larger the volume of milk, the quicker it passes through the digestive tract. Large volumes of milk may pass through a baby's small intestine too quickly for all of the lactose to be digested.
Feeding stimulates the gastro-colic reflex. This reflex causes contractions of the intestines which move the contents along. (This reflex action is why babies often poop or pass gas during feeding). If a baby is fed again before the previous feed is fully digested the gastro-colic reflex will push some of the undigested milk from the small intestine through to the large intestine (bowel).
In the large bowel, undigested lactose draws in extra water through a process called osmosis. The lactose is then fermented by bacteria normally present in the bowel, and this produces gas. The end result is excessive gas, cramps, bloating and frequent watery, acidic stools (poop) which may scald a little bottom.
As the gas and fluid build up in the baby's large bowel this causes her discomfort. She then begins to act like she's hungry because she knows that feeding will provide comfort for her, which it does - but only temporarily. Unfortunately, this may provide another large feed or another feed with a disproportionate amount of foremilk to hindmilk, which then results in more gas, more watery stools and more discomfort, and the cycle continues.
Lactose overload is frequently misdiagnosed as lactose intolerance. Both conditions display identical gastric symptoms. However, unlike lactose intolerance, where the child fails to gain weight (or loses weight) and is very unwell, an infant with lactose overload is healthy and thriving.
Lactose intolerance arises when a person does not produce enough lactase to break-down lactose into glucose and galactose, which can then be absorbed into the blood supply. For an infant, this means they are then deprived of their major source of energy (calories) provided by glucose. Along with the gastric symptoms, the lactose intolerant child will fail to gain weight or lose weight and become very unwell.
In lactose overload, the infant produces sufficient quantities of lactase to break down enough lactose to provide glucose and galactose essential for healthy growth, but does not produce enough lactase in time to digest all of the lactose contained in feedings that contain a disproportionate amount of foremilk to hindmilk. Or in the situation of an overfed formula fed baby, does not produce enough lactase to adequate digest all of the lactose contained in large volumes of milk. As the undigested lactose passes into the large bowel this causes gastrointestinal symptoms. However, unlike the child with lactose intolerance, these infants are healthy and thriving
A baby experiencing gastrointestinal symptoms due to lactose overload will show positive results to present day tests for lactose intolerance. As a result they are commonly misdiagnosed as lactose intolerant. Sadly, many nursing mothers are mistakenly advised to wean their babies from the breast onto a lactose-free formula. Lactose-free formula will relieve the symptoms of lactose overload but is totally unnecessary (in most situations) as minor changes to feeding management will also relieve the symptoms - without the need to wean to formula.
Lactose-free formula will relieve gastrointestinal symptoms related to lactose overload in formula fed babies as well. However, lactose-free formula is rarely necessary when the problems leading to overfeeding have been addressed.
Unfortunately, many healthy, thriving baby's are incorrectly labeled as 'lactose intolerant'. This may result in a lifetime of unnecessary dietary restrictions, deprived of their only or most valuable source of galactose.
For breast fed babies
The key to correcting the problem of foremilk-hindmilk imbalance, which leads to lactose overload, is to ensure your breasts are adequately emptied before switching sides. You might be switching sides too soon by offering both breasts at each feed, or it could be that you are alternating sides too often if you are already one-sided breastfeeding.
You will know when you have this problem under control when your baby stools decrease in frequency, thicken in consistency and gassiness lessens. Green stools will gradually become yellow/mustard color.
IMPORTANT: Caution should be used with same side feeding as it can decrease supply. When making changes to feeding management it is important to closely monitor the number of wet diapers your baby has each day. There should be 5 or more wet disposable diapers or 6 or more wet cloth diapers each day. Weekly weight checks may also be helpful to reassure you that your baby is getting enough.
Facts about lactose and breast feeding
For formula fed babies
Written by Rowena Bennett
Infant sleep problems often underpin feeding problems like lactose overload. If you like this article you will love Rowena's new book 'Your Sleepless Baby: The Rescue Guide'.
© Copyright www.babycareadvice.com 2003. All rights reserved.
Added Nov 2003. Last reviewed Mar 2013.
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