1) Describing lactose-free infant formula
Lactose is the main sugar in breast milk, cow’s milk, and many formulas. Lactose-free formula contains cow’s milk protein, but nearly all of the lactose has been replaced by another sugar such as corn syrup solids or brown rice syrup. Formula can also have reduced amounts of lactose.
2) The use of lactose-free infant formula
Lactose-free infant formula was previously recommended for infants with diarrhea and other gut problems. It was thought even mild gut illness caused damage to the lining of the gut and resulted in low levels of the enzyme lactase, needed to digest lactose. It was even used instead of breast milk.
Research has since shown that for most babies, lactose-free formula did not have any advantages over regular formula and was inferior to breast milk.
Infant formula-fed babies with persistent diarrhea or who have major health problems that can reduce the amount of lactase enzyme may benefit from a short trial of lactose-free infant formula.
There are very few conditions in which babies cannot tolerate lactose. Two conditions are congenital lactase deficiency, caused by the baby's bowel not making the lactase enzyme, and galactosemia, a disorder that prevents the body from processing the milk sugar component galactose. Lactose-free infant formula is not suitable for these babies as it may contain residual lactose.
Both lactose-reduced and lactose-free formula are often marketed as decreasing stomach gas and crying. There is very little evidence to support this (Sherman 2015).
3) The risks of using lactose-free infant formula
There are drawbacks to using lactose-reduced or lactose-free formula. These formulas are generally more expensive than regular formula.
Lactose itself has beneficial effects (Romero-Velarde 2019):
- Compared to glucose or sucrose, it is less likely to stimulate the reward centre of the brain.
- Formula with corn sugar has been shown to raise the insulin level higher than lactose-containing formula.
- Lactose helps the body absorb calcium from milk.
Brown rice syrup, which is sometimes used to replace lactose, may contain arsenic.