Is Lactose Intolerance Genetic?

Lactose intolerance is a common condition in which an individual lacks the ability to fully digest lactose, a sugar found in milk and dairy products.

The primary cause of lactose intolerance is the lack of an enzyme called lactase, which is responsible for breaking down lactose in the small intestine.

While there are many factors that can contribute to lactose intolerance, genetics play a major role in determining an individual’s risk for the condition.

What are the main genes that influence the risk for lactose intolerance?

Several genes have been identified that can influence an individual’s risk for lactose intolerance. These genes are involved in the production and regulation of lactase, the enzyme responsible for breaking down lactose. Here are some of the main genes that have been found to play a role in lactose intolerance:

LCT gene

The LCT gene provides instructions for making lactase, the enzyme responsible for breaking down lactose. Variations in this gene can affect the production and activity of lactase, and thus an individual’s ability to digest lactose. There are several known variations in the LCT gene that have been associated with lactose intolerance, including a mutation called C/T-13910, which is found in many individuals of East Asian and African descent.

MCM6 gene

The MCM6 gene is located next to the LCT gene and is involved in regulating its activity. Specifically, variations in the MCM6 gene can affect the production of a protein called a lactase enhancer, which can increase or decrease the activity of the LCT gene. Variations in the MCM6 gene have been found to be strongly associated with lactose intolerance in many populations.

TPH2 gene

The TPH2 gene is involved in the production of serotonin, a neurotransmitter that plays a role in regulating mood and appetite. However, recent studies have also found that the TPH2 gene may be involved in lactose intolerance. Specifically, variations in the TPH2 gene have been found to be associated with a decreased production of lactase and an increased risk for lactose intolerance.

LPH gene

The LPH gene provides instructions for making an enzyme called lactase-phlorizin hydrolase, which is also involved in the breakdown of lactose. Variations in the LPH gene have been found to be associated with lactose intolerance in some populations.

Environmental factors affecting lactose intolerance

While these genes have been identified as playing a role in lactose intolerance, it’s important to note that genetics is only one factor that can contribute to the condition.

Environmental factors, such as diet and gut microbiota, can also play a role in lactose intolerance.

Additionally, the expression of these genes can be influenced by epigenetic factors, such as DNA methylation and histone modifications, which can affect how genes are turned on or off.

Final remarks

Lactose intolerance is a common condition that is influenced by genetics as well as environmental and epigenetic factors. Several genes have been identified that play a role in the production and regulation of lactase, the enzyme responsible for breaking down lactose.

While more research is needed to fully understand the complex interplay between genetics and lactose intolerance, these findings can provide valuable insights into the underlying mechanisms of the condition and may help guide the development of new treatments and interventions in the future.

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References

Enattah, N. S., Sahi, T., Savilahti, E., Terwilliger, J. D., Peltonen, L., & Järvelä, I. (2002). Identification of a variant associated with adult-type hypolactasia. Nature Genetics, 30(2), 233-237. doi: 10.1038/ng826 Link
Ingram, C. J., Mulcare, C. A., Itan, Y., Thomas, M. G., & Swallow, D. M. (2009). Lactose digestion and the evolutionary genetics of lactase persistence. Human Genetics, 124(6), 579-591. doi: 10.1007/s00439-008-0593-6
Hertzler, S. R., & Savaiano, D. A. (1996). Colonic adaptation to daily lactose feeding in lactose maldigesters reduces lactose intolerance. The American Journal of Clinical Nutrition, 64(2), 232-236. doi: 10.1093/ajcn/64.2.232
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Kim, J. H., Kim, Y. H., Kim, D. H., & Jung, H. C. (2019). Association between genetic polymorphism of tryptophan hydroxylase 2 and lactose intolerance in Korean adults. Nutrients, 11(11), 2803. doi: 10.3390/nu11112803
Krawczyk, M., & Wolska, M. (2017). The role of epigenetic modifications in the development of lactose intolerance. Nutrients, 9(3), 212. doi: 10.3390/nu9030212