The Science Behind Lactose Intolerance: A Global Perspective

In this podcast episode, Adam Regusia discusses lactose intolerance and its prevalence in different populations. He explores the evolutionary history of lactase persistence, the ability to digest lactose beyond infancy, and how it is more common in Northern Europeans. He also discusses the various types of lactose intolerance and the potential role of gut microbiome in this condition. Adam shares personal experiences with lactose intolerance and highlights the availability of lactase supplements and alternative dairy products for those with lactose intolerance. He concludes by encouraging listeners to embrace their individual traits and choices surrounding lactose consumption.

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Key Insights:

  • Lactose intolerance is a common condition that affects many people globally.
  • Lactose intolerance can be intermittent, with symptoms such as bloating, cramping, gas, and diarrhea.
  • There are various factors that contribute to lactose intolerance, including genetics, age, and gut health.
  • Mammals, including humans, typically become lactose intolerant as they reach adulthood.
  • Lactose intolerance is considered the norm, with lactase persistence (ability to digest lactose) being a relatively recent evolutionary adaptation.
  • Northern Europe has a high prevalence of lactase persistence, likely due to historical and environmental factors.
  • Lactase supplements and other dairy alternatives are available to help manage lactose intolerance symptoms.
  • Different populations have different rates of lactose intolerance due to genetic and historical factors.
  • Lactose intolerance can be influenced by diet, with fiber and fat potentially affecting symptoms.


It’s the Adam regusia podcast episode 36 and I want to milk out an episode about milk. Lactose intolerance is on my mind lately as I seem to be experiencing bouts of it. Yes, lactose intolerance can apparently be intermittent, it comes and goes in some people. And let me tell you, it has come for me – bloating, abdominal cramping, gas, and diarrhea even from just a little ice cream. I know I shouldn’t be eating it, but have you tried these Nightingale ice cream sandwiches? #notanad. Nightingale is this originally mom and pop operation out of Richmond, Virginia. They make these giant, gold bar-shaped ice cream sandwiches that come in brown paper bag packaging. I get them at the grocery chain, Fresh Market. They’re apparently available nationwide in the United States. The cookies are super thick and chewy, and the ice cream layer is really thick too. I usually use a knife to cut little bites off of the sandwich. The triple chocolate flavor is my favorite, but there’s also a blondie flavor that is insane. Get yourself a Nightingale Ice Cream Sandwich if you can find one. They have a line of mini sandwiches called Chomps that you can get at Walmart now. Just one little Chomp is enough to completely ruin my night at the moment because I am going through a majorly lactose intolerant phase, which much of the rest of the world might refer to as adulthood.

The pathologization of lactose intolerance is one of the classic examples of eurocentric bias in science and medicine, also the bias of the agro-industrial or regulatory complex. Most people on this Earth are lactose intolerant, or at least they are milk intolerant in some way. Most mammals on this Earth are milk intolerant when they become adults. One of the defining traits of the mammalian class of animals is our sweat glands that we use to maintain a constant body temperature, and some evolutionary biologists argue that mammary glands evolved from sweat glands. Mammals have mammary glands that make milk. It has been speculated that milk might have first evolved as a means of keeping eggs moist when they’re outside of the body. Essentially, milk is the perfect food for early development.

Milk contains lactose, which is a disaccharide like table sugar. Humans make a ton of lactose in our milk, whereas cow’s milk and goat’s milk have lower lactose content. Some people who can’t tolerate cow’s milk say that they can tolerate goat’s milk, but it could also have to do with the protein content of the milk. Scientists have implicated a particular protein called A1 beta casein as a digestive irritant in some people. Cow’s milk tends to have a lot of A1 beta casein, while goat’s milk has different beta caseins. Lactose intolerance may actually be cow’s milk intolerance specifically.

Lactose intolerance is the normal state of being for grown-up mammals. Most adult mammals, including humans, make little to no lactase enzyme, which is required to digest lactose. Congenital lactose intolerance, where babies are born without the ability to produce lactase, is very rare because historically, most people with that mutation would not have survived to pass it on to the next generation.

Lactase persistence is a relatively recent evolutionary adaptation among some human populations. Lactase persistence has evolved independently in a few different human populations, including in East Africa, Central Asia, and Arabia. However, lactase persistence is most prevalent in Northern Europe. The reason behind this prevalence is not entirely clear, but it may be linked to a combination of factors such as the need for calcium absorption in dark and cold environments, vitamin D deficiency due to lack of sunlight, and gut microbiome adaptations.

There are several types of lactose intolerance, and symptoms can vary from person to person. Some people can handle lactase supplements or lactose-reduced milk products, while others may experience no improvement. Gut health and microbiome composition may also play a role in lactose intolerance.

In conclusion, lactose intolerance is a normal and natural state for most people on Earth. While it may be viewed as a pathology on an individual level, it is important to respect and accept one’s own body and make choices based on personal needs and preferences. There are various options available for lactose-intolerant individuals, including lactase supplements, lactose-reduced products, and exploring alternative food sources.