Lactose: the Plain Truth

A brief Q&A article highlighting the facts about lactose.

What is lactose?

Lactose is the primary carbohydrate found in mammalian milk. Lactose is broken down into glucose and galactose by lactase in the small intestines. Galactose may be further metabolized to glucose or used to create galactose-containing proteins and fats, which are vital for functions such as chemical signaling and building cellular structures.

If galactose is not provided in the diet, the body is able to produce galactose to meet its requirements.1 Infants and young children have higher endogenous production rates of galactose compared to adolescents and adults.2

What is lactose intolerance?

When there is not enough lactase, the body is unable to digest significant amounts of lactose. This unabsorbed lactose leads to gastrointestinal problems such as abdominal pain, bloating, gassiness and diarrhea. The occurrence of symptoms associated with the incomplete digestion of lactose is known as lactose intolerance.

Decline in lactase concentrations occurs at weaning for most individuals, and the molecular basis of hypolactasia is hard-wired.3

If a child does not consume lactose, will there be any long term health effects?

Current evidence indicates that the absence of lactose from formulas does not compromise normal development or safety in infants.

A prospective, blinded, randomised clinical trial was conducted among healthy, normal term infants where participants were fed a lactose-free milk-based formula or a standard commercial lactose-containing milk-based formula for 112 days. Growth (weight, length, and head circumference) were found to be similar and normal in both groups, and serum biochemistries were also within infants’ normal reference ranges.4

In a recent prospective study of infants fed soy formulas (i.e. lactose-free), all scores on developmental testing, including cognitive test scores, were found to be within established normal ranges and did not differ significantly from infants fed a lactose-containing, cow milk-based formula.5

Will calcium intake be affected if a lactose-free formula is used?

Research has shown that the absorption of calcium from a lactose-free infant formula is adequate to meet the calcium needs of full-term infants when the formula’s calcium content is similar to that of lactose-containing, cow-milk-based infant formulas.6

What are the available lactose-free options?

Lactose-free options include soy and cow milk protein–based formulas. In these formulas, lactose is replaced with sucrose, maltodextrin or corn syrup to provide carbohydrates.


1. Harvey RA, Ferrier DR. Lippincott’s Illustrated Reviews: Biochemistry. Fifth Edition. Lippincott Williams & Wilkins; 2011.
2. Coelhoa AI, et al. Curr Opin Clin Nutr Metab Care 2015;18:422–427.
3. Kleinman RE, Greer FR (eds). Pediatric Nutrition. 7th edition. Elk Grove Village, IL: American Academy of Pediatrics; 2014.
4. Lasekan JB, et al. Clin Pediatr (Phila) 2011;50:330-7.
5. Andres A et al. Pediatrics 2012;129:1134-40.
6. Abrams SA et al. Am J Clin Nutr. 2002 Aug;76:442-6.

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