What is Lactose? How is it digested?
The main sugar in both breast milk and other animal milks is lactose., and it is digested by an enzyme (chemical which helps digestion) Lactase present on our upper small intestine cell lining.
The enzyme level increases in the immediate newborn period and over time, the levels reduce. Lactose is the most abundant carbohydrate of most mammalian milk types, human milk contains approximately 70 g/L of lactose, for comparison, cow’s milk contains approximately 46 g/L of lactose.
What is the importance of Lactose?
Lactose has important benefits-its components are needed for brain tissue growth and maturation, it helps with calcium absorption, it reduces risk of dental caries and does not stimulate the reward center of the brain, so does not prompt overeating!
What is Lactose intolerance?
When we are deficient in the enzyme lactase (to varying degrees), the lactose passes unabsorbed in our intestine-there is more production of products like acetic and butyric acids. This leads to flatulence, bloating, griping and in younger kids, frothy acidic stools which causes persistent diaper rash.
How does it affect babies?
In the newborn period and in the first 2-3 months of life, many parents are concerned about the watery stool pattern, diaper rash and colic in babies. Many physicians consider these as evidence of lactose intolerance and advice stool tests (including reducing sugars, stool pH etc.). There is also significant confusion due to the overlapping features of lactose intolerance and cow’s milk protein intolerance. There is a range of lactase levels in babies, and the enzyme increases with time with consistent exposure to lactose in milk-so in most babies, the symptoms improve with time.
How do we manage this in babies?
Appropriate and adequate skin care of the nappy area to avoid rash (avoiding pressure during cleaning, preventive use of barrier nappy cream) and avoiding overfeeding to avoid exposure to a high lactose load are the only measures needed in breast feeding babies.
Colic is a transitional phase in the infant’s development, and though a degree of lactose intolerance could contribute, it is not justified to substitute breast milk for this reason. The benefits of breast milk far outweigh any transient discomfort the baby faces-and simple reassurance that the problem is transient and supporting the family should be adequate.
If the baby is partly on infant formula feeds for any reason (difficulty in exclusive breast feeding, family choice etc.), a trial on low lactose infant formula could be considered, with stress on not modifying the breast feeding at the same time. Mothers may benefit from feeding support.
What is secondary lactose intolerance?
There is a pattern of transient and secondary lactase deficiency due to loss of the brush border cells of the small intestine following an acute gastroenteritis-this usually follows an episode of diarrhea, and leads to persistent loose stools, diaper rash etc. A brief period of low or lactose free infant formula can help in this setting. Once the stool pattern improves and the nappy rash has healed (zinc supplements could help too in this setting), gradual change back to the previous feeding pattern is usually well tolerated over a 10-14 day period.
Does lactose intolerance affect older children and adults?
Most mammals stop producing lactase enzyme after the breastfeeding phase. However, after domestication of cow and intake of dairy products by humans, lactase persistence has been noted in varying proportions-largely related to proportion of milk intake in the population group (cultural and ethnic variations).
Nearly 70% of adults in the world are lactase non persistent to a degree-this proportion is lower in Northern Europe (only around 2%) while in other regions like South America, Africa and parts of Asia, it is as high as 50%. Very few children under 6 years of age also have lactase non-persistence leading to lactose intolerance-the incidence increases with age. In older kids, the symptoms can be overcome by reducing the dose of dairy products to a level that is tolerated so that the lactose dose is reduced.
The composition of breast milk and the reason why nature has designed it this way is intriguing. Lactose in milk is one such factor and though majority of older kids and adults have relative lactase deficiency due to non-persistence of lactase enzyme, a simple approach to the management as dictated by common sense is adequate in majority of the situations.
One very important message here is that breast feeding should not be disturbed for transient lactose intolerance-supporting breast feeding and helping the mother come out of this transient phase is very important.