What is Lactose?
August 28, 2024 ⬝ Written by Lactose Liberators
What is Lactose?
Lactose is a natural sugar found in milk and dairy products, serving as the primary carbohydrate in these foods [1]. Understanding lactose and its effects on the body is essential for many people’s dietary choices and health management.
A Brief History of Lactose Intolerance
Lactose intolerance has been a part of human history for thousands of years. Originally, all humans, like other mammals, lost the ability to digest lactose after weaning. However, around 10,000 years ago, a genetic mutation appeared in some populations, allowing them to continue producing lactase into adulthood. This trait, known as lactase persistence, became more common in populations that relied heavily on dairy farming such as those in northern Europe [2,3].
The Role of Lactase and Lactose
Lactose is a disaccharide composed of glucose and galactose and has the chemical formula C₁₂H₂₂O₁₁. Lactase, an enzyme produced in the small intestine, breaks down these simpler sugars, as illustrated in Figure 1.
Figure 1. Lactase enzyme breaks down lactose in galactose and glucose [6].
In people with lactose intolerance, the production of lactase is reduced or absent, leading to difficulties in digesting lactose [3,4]. This lack of sufficient lactase means that lactose passes undigested into the large intestine. There, gut bacteria ferment the lactose, producing gasses and other byproducts. This process leads to the characteristic symptoms of lactose intolerance [3,4].
Symptoms of Lactose Intolerance
Common symptoms include:
- Bloating
- Belly (abdominal) cramps and pain
- Gas
- Nausea
- Diarrhea
These symptoms typically occur 30 minutes to 2 hours after consuming lactose-containing foods [1,4].
Prevalence and Genetic Factors
Contrary to common misconceptions, lactose intolerance is not a disorder or disease, but rather a normal biological state for most of the world’s adult population [2,3]. It’s estimated that about 65% of the global human population has a reduced ability to digest lactose after infancy. The prevalence varies widely between populations, influenced by long-term dietary habits and genetic factors [3,5].
Lactase persistence - the ability of adults to digest the lactose in milk - is actually the genetic exception, not the norm. Understanding this can help destigmatize lactose intolerance and recognize it as a common and natural variation in human biology.
Diagnosis and Management
Lactose intolerance can be diagnosed through various methods, including:
- Hydrogen breath test
- Lactose tolerance test
- Genetic test
- Stool acidity test
Management typically involves reducing or eliminating lactose from the diet, using lactase enzyme supplements, or consuming lactose-free dairy products. Many people with lactose intolerance can tolerate small amounts of lactose, especially when consumed with other foods. It is important to recognize that everyone reacts to lactose differently and there may be certain foods that cause less severe symptoms which can be good dietary choices [1,4]. For instance, you may prefer having yogurt over ice cream since it causes much less bloating for you.
Remember that having lactose intolerance doesn't mean you're unhealthy or your diet is deficient without milk. Many cultures around the world have thrived on low-lactose or lactose-free diets. With proper nutritional planning, individuals with lactose intolerance can easily meet their dietary needs and lead healthy lives [4].
Our Mission
We hope this information about lactose and lactose intolerance has been helpful and provides you with a comprehensive understanding of this common condition. Whether you're dealing with lactose intolerance yourself, know someone who is, or are simply curious about the science behind it, we believe that knowledge is the first step toward destigmatizing lactose intolerance. While lactose intolerance can be challenging, many people successfully manage it with dietary adjustments and medical guidance. If you suspect you might be lactose intolerant, we encourage you to speak with a healthcare professional for proper diagnosis and personalized advice.
References
[1] National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). "Lactose Intolerance." https://www.niddk.nih.gov/health-information/digestive-diseases/lactose-intolerance
[2] Ségurel L, Bon C. On the Evolution of Lactase Persistence in Humans. Annu Rev Genomics Hum Genet. 2017;18:297-319. doi:10.1146/annurev-genom-091416-035340
[3] Mattar R, de Campos Mazo DF, Carrilho FJ. Lactose intolerance: diagnosis, genetic, and clinical factors. Clin Exp Gastroenterol. 2012;5:113-121. doi:10.2147/CEG.S32368
[4] Misselwitz B, Butter M, Verbeke K, Fox MR. Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. Gut. 2019;68(11):2080-2091. doi:10.1136/gutjnl-2019-318404
[5] Itan Y, Jones BL, Ingram CJ, Swallow DM, Thomas MG. A worldwide correlation of lactase persistence phenotype and genotypes. BMC Evol Biol. 2010;10:36. doi:10.1186/1471-2148-10-36
[6] Image: Lactase breaking down lactose. https://www.shutterstock.com/image-illustration/lactose-made-galactose-glucose-intolerance-occurs-1299524908
