Unlocking the Mystery of Lactase Persistence: A Guide to Genetic Testing and Diagnosis

Expert Reviewed By: ⁠Dr. Brandon Colby MD

For many people across the globe, consuming dairy products is a normal part of their daily diet. However, for those with lactase persistence, a condition where the body continues to produce lactase, the enzyme needed to break down lactose found in milk and dairy products, this seemingly simple act can lead to digestive issues and discomfort. Lactase persistence is an inherited genetic trait, and understanding, diagnosing, and using genetic testing for this condition can provide valuable insights into one’s own health and dietary needs.

The Science Behind Lactase Persistence

Research has shed light on the genetic basis of lactase persistence, revealing that it is primarily determined by specific nucleotide variants in the lactase gene. In a study titled In Vitro Functional Analyses of Infrequent Nucleotide Variants in the Lactase Enhancer, scientists examined four candidate functional variants in the lactase gene, uncovering different molecular routes to increased lactase promoter activity and lactase persistence.

Historical and Cultural Context

Historically, lactase persistence was not as common as it is today. In a study analyzing lactase gene-associated single nucleotide polymorphisms (SNPs) in Joseon period human remains from Korea, titled Revealing Joseon period People’s single nucleotide polymorphism associated with lactase gene by ancient DNA analysis of human remains from archaeological sites in Korea, researchers confirmed lactase non-persistent genotypes in pre-modern Korean people. This finding is consistent with other studies exploring the evolution of genetic and cultural variation, such as Demography and the evolution of genetic and cultural variation, which uses gene-culture coevolution and population genetics theories, along with genetic and archaeological data, to better understand the development of this trait over time.

Health Implications of Lactase Persistence

While lactase persistence may seem like a harmless genetic variation, it has been linked to certain health outcomes. In a study titled Evaluation of Relationships Among National Colorectal Cancer Mortality Rates, Genetic Lactase Non-Persistence Status, and Per Capita Yearly Milk and Milk Product Consumption, researchers found a positive correlation between dairy food intake and colorectal cancer mortality rates, and a negative correlation between lactase non-persistence prevalence and colorectal cancer mortality rates. This highlights the importance of understanding one’s lactase persistence status in relation to overall health and disease risk.

Genetic Testing for Lactase Persistence

Thankfully, advances in genetic testing have made it possible to determine an individual’s lactase persistence status with relative ease. Genetic testing can be helpful for this disorder in several ways:

1. Identifying Lactase Persistence

Genetic testing can identify the specific nucleotide variants associated with lactase persistence, allowing individuals to better understand their own genetic makeup and how it may affect their ability to digest lactose.

2. Guiding Dietary Choices

Knowing one’s lactase persistence status can inform dietary choices, helping individuals make more informed decisions about consuming dairy products and potentially avoiding the discomfort and digestive issues associated with lactose intolerance.

3. Assessing Disease Risk

As mentioned earlier, lactase persistence has been linked to certain health outcomes, such as colorectal cancer. Genetic testing can provide individuals with valuable information about their own disease risk, allowing them to take preventative measures and work with their healthcare providers to develop personalized health plans.

In conclusion, understanding, diagnosing, and using genetic testing for lactase persistence can provide valuable insights into an individual’s health, dietary needs, and disease risk. As genetic testing becomes more accessible and affordable, it is becoming an increasingly important tool in the quest for personalized healthcare and disease prevention.

About The Expert Reviewer

Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of  and the author of ⁠⁠Outsmart Your Genes.

Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (⁠⁠ACMG), an Associate of the American College of Preventive Medicine (⁠⁠ACPM), and a member of the National Society of Genetic Counselors (⁠NSGC)