Reviewed by: Tori Schmitt, MS, RDN, LD, Director of Nutrition Services
Lactose is the main carbohydrate in human milk, and it is often included in infant formula. This article summarizes the science on lactose in infant formula to better understand this important energy source as a key building block of both human milk and infant formula.
What is lactose?
Human milk and infant formula are both composed of protein, carbohydrates, fat, vitamins, and minerals. Lactose is the primary carbohydrate in human milk and makes up about 40% of the total energy intake of breastfed babies.2 Lactose is composed of two simple sugar molecules, glucose and galactose, and our bodies can break aprt lactose in our small intestine using an enzyme called lactase.-
Lactose in infant formula
There is a large amount of lactose-reduced formula purchased in the United States. In a study exploring the macronutrient content of powdered infant formula purchased in the United States between 2017 and 2019, 59% of all formula purchased was lactose-reduced, meaning that formula was made with partial lactose or as a lactose-free formula. Of all standard formulas, 32% were lactose-reduced. The same study found that hypoallergenic formula was purchased in greater volume than anticipated given the prevalence of cow’s milk protein allergy, suggesting that a greater number of infants were fed this formula type than might be medically indicated.
What does the research about lactose and infant formula tell us?
As the prevalence of lactose-reduced formula has risen in the United States, an increasing amount of research has been done exploring the impact of lactose-reduced formula on infants receiving it. Below are the key takeaways regarding lactose and infant formula, with a focus on findings from recent studies:
Lactose intolerance in infants is quite rare
Most babies begin making lactase, the enzyme that helps break down lactose, while they are still in utero so they are ready to digest lactose from either human milk or formula from the moment they are born.While a phenomenon called lactose intolerance, characterized by a gradual decline in lactase activity, affects about 70% of the adult population, it occurs gradually after a baby has weaned, typically no sooner than 5 years of age. True lactase deficiency, characterized by extremely low or absent lactase activity, is incredibly rare and is identified shortly after birth.3 Even infants born prematurely, who may experience reduced lactase activity or developmental lactase deficiency, tend to experience symptoms that are typically transient.3
Lactose alternatives are not the ideal choice for the healthy term infant.
All infant formulas made and sold in the US have to meet the US FDA nutrition requirements as outlined in the Infant Formula Act, which includes strict total amounts of carbohydrates. When lactose is removed from formula, it is replaced with other carbohydrates, such as corn syrup solids, to ensure the total carbohydrate content meets the FDA requirement. Research has found that the implications of these substitutions are not benign. A recent observational study investigated the impact of formula carbohydrate composition on children exclusively formula-fed from 3 months of age onward. The study involved over 15,000 children enrolled in WIC and followed them through four years of age. When exploring associations between obesity prevalence and consumption of lactose-reduced formula containing corn syrup solids, it was found that children receiving lactose-reduced infant formula with corn syrup solids were likelier to be obese in toddlerhood than children who had not consumed lactose-reduced formula. “The trend towards replacing lactose in infant formula with glucose-based sugars like corn syrup is concerning because it deprives infants of galactose, an essential sugar for growth and development, and increases glucose-based sugars, which does not reflect the composition of breast milk,” states author Michael Goran, Ph.D.
Shift the focus to protein
There is no strong evidence that a reduced lactose or lactose-free formula will alleviate fussiness, or colic in infants without an identified medical problem., If there is concern about an infant tolerating a formula, the focus does not necessarily have to be carbohydrates, as the lactose intolerance myth has been busted. Instead, the discussion can, and often should, be about protein. For some infants who experience excessive gas, fussiness, crying, or allergies - smaller protein sizes may be beneficial. Breaking down the protein size is what occurs via a process called ‘hydrolysis’. This is used to make partially hydrolyzed, extensively hydrolyzed, and amino acid-based formulas and can occur independent of lactose substitutions.
Conclusion
Understanding the role of lactose and the current science on lactose in infant formula helps us better understand clinical implications from scientific publications and identify additional areas that require research. Possible areas of future research include additional large-scale studies replicating the results of current studies and mechanistic studies. Further exploration is also warranted around the impact of lactose-reduced formula as relates to changes in the gut microbiota and its impact on blood glucose.6
Want to learn more about lactose in infant formula? Check out our CE Webinar on Carbohydrates in Infant Formula featuring Dr. Michael Goran.
References
1 Martin, C. R., Ling, P. R., & Blackburn, G. L. (2016). Review of infant feeding: key features of breast milk and infant formula. Nutrients, 8(5), 279.
2 Grenov, B., Briend, A., Sangild, P. T., Thymann, T., Rytter, M. H., Hother, A. L., Mølgaard, C., & Michaelsen, K. F. (2016). Undernourished children and milk lactose. Food and nutrition bulletin, 37(1), 85–99. https://doi.org/10.1177/0379572116629024
3 Heine, R. G., AlRefaee, F., Bachina, P., De Leon, J. C., Geng, L., Gong, S., Madrazo, J. A., Ngamphaiboon, J., Ong, C., & Rogacion, J. M. (2017). Lactose intolerance and gastrointestinal cow's milk allergy in infants and children - common misconceptions revisited. The World Allergy Organization journal, 10(1), 41. https://doi.org/10.1186/s40413-017-0173-0
4 Delahanty, L., et. al. Nutrition in the prevention and treatment of disease. Netherlands: Elsevier Science. 2017.
5 Fassio, F., Facioni, M. S., & Guagnini, F. (2018). Lactose maldigestion, malabsorption, and intolerance: A Comprehensive review with a focus on current management and future perspectives. Nutrients, 10(11), 1599. https://doi.org/10.3390/nu10111599
6 Anderson, C. E., Whaley, S. E., & Goran, M. I. (2022). Lactose-reduced infant formula with corn syrup solids and obesity risk among participants in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). The American journal of clinical nutrition, 116(4), 1002–1009. https://doi.org/10.1093/ajcn/nqac173
7 Strzalkowski, A. J., Järvinen, K. M., Schmidt, B., & Young, B. E. (2022). Protein and carbohydrate content of infant formula purchased in the United States. Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology, 52(11), 1291–1301. https://doi.org/10.1111/cea.14232
8 Roy, D., Ye, A., Moughan, P. J., & Singh, H. (2020). Composition, Structure, and Digestive Dynamics of Milk From Different Species-A Review. Frontiers in nutrition, 7, 577759. https://doi.org/10.3389/fnut.2020.577759
9 Gordon, M., Biagioli, E., Sorrenti, M., Lingua, C., Moja, L., Banks, S. S., Ceratto, S., & Savino, F. (2018). Dietary modifications for infantile colic. The Cochrane database of systematic reviews, 10(10), CD011029. https://doi.org/10.1002/14651858.CD011029.pub2
10 Sherman, A. L., Anderson, J., Rudolph, C. D., & Walker, L. S. (2015). Lactose-Free Milk or Soy-Based Formulas Do Not Improve Caregivers' Distress or Perceptions of Difficult Infant Behavior. Journal of pediatric gastroenterology and nutrition, 61(1), 119–124. https://doi.org/10.1097/MPG.0000000000000743
11 Jones, R. B., Berger, P. K., Plows, J. F., Alderete, T. L., Millstein, J., Fogel, J., Iablokov, S. N., Rodionov, D. A., Osterman, A. L., Bode, L., & Goran, M. I. (2020). Lactose-reduced infant formula with added corn syrup solids is associated with a distinct gut microbiota in Hispanic infants. Gut microbes, 12(1), 1813534. https://doi.org/10.1080/19490976.2020.1813534
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