Understanding lactose and the over-diagnosis of lactose intolerance

What is lactose? Lactose is the primary carbohydrate component in milk. It is a disaccharide, a small sugar unit composed of two smaller monosaccharides. The human body uses enzymes to help breakdown lactose and convert it into usable forms of energy. Lactose is one part glucose and one part galactose, both of which are naturally occurring sugars used by the human body. How is lactose digested and what are its benefits? After consumption, lactose is broken apart into its monosaccharide components with the help of the enzyme lactase. The lactase enzyme is produced by cells that line the small intestine of the human digestive system. The glucose that is released from this cleaving process can be used immediately for energy production. The galactose is first sent to the liver for processing by several enzymes and is then converted into glucose or glycogen (stored glucose). Lactose makes up over a third of the consumable calories in a newborn’s diet and is an extremely rich and beneficial source of energy for growth and development. Emerging research also suggests lactose plays an important role in fortifying gut health and reinforcing bone growth and development. What is lactose intolerance and what is a milk allergy? Lactose intolerance is a condition in which the human body does not naturally produce the lactase enzyme for the breakdown of lactose. Lactose intolerance is not an allergy, as it does not involve an immune system response. Nearly every infant is born with the ability to produce lactase and it is exceedingly rare for an infant to be lactose intolerant. Studies and estimates suggest 1 in every 60,000 newborns may be lactose intolerant. This can be explained through biological evolution, as mammalian young are biologically programmed to consume milk during their infancy. The prevalence of lactose intolerance among older children and some adults is also biologically rooted, as most mammals do not continue to consume dairy after the weaning process. Outside of extremely rare genetic conditions, most infants have no need for a lactose free diet in the first years of life. A milk allergy, also known as Cow Milk Protein Allergy, or CMPA, involves a bodily immune response to the protein content in cow milk. With CMPA, the body biologically views certain casein and whey proteins as potential pathogens and stimulates an immune response releasing histamine and other inflammatory signals in an attempt to protect the body. This response can lead to digestive problems and skin related issues. While still relatively rare, studies estimate CMPA may affect between 2 to 3% of newborns. If a milk related diagnosis is suspected for an infant, there is a much higher probability it is a CMPA issue and not a lactose related issue. Research showing the benefits of lactose for infants and the statistical data on lactose intolerance supports the continued use of lactose in infant based formula. Summary Lactose intolerance, a condition in which the lactase enzyme is not produced naturally, is distinct from a milk allergy, which involves an immune response to cow milk proteins. Lactose intolerance is rare among infants, while a milk allergy, known as Cow Milk Protein Allergy (CMPA), affects a small percentage of newborns. Research supports the use of lactose in infant formula due to its benefits and the low incidence of lactose intolerance. Understanding the differences between lactose intolerance and milk allergy is crucial in avoiding the overdiagnosis of lactose intolerance in infants.

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References

• https://medlineplus.gov/genetics/condition/lactose-intolerance/#frequency Date Accessed 5/28/2023
• Malik TF, Panuganti KK. Lactose Intolerance. [Updated 2023 Feb 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532285/
• Deng Y, Misselwitz B, Dai N, Fox M. Lactose Intolerance in Adults: Biological Mechanism and Dietary Management. Nutrients. 2015 Sep 18;7(9):8020-35. doi: 10.3390/nu7095380. PMID: 26393648; PMCID: PMC4586575.