Can’t Digest Dairy? Here’s What Might Be Happening

If your stomach protests every time you enjoy a scoop of ice cream or pour milk into your tea, you might be dealing with lactose intolerance. It’s incredibly common and often misunderstood. Let’s clear things up and explore how your gut health might be involved.

What Is Lactose Intolerance?

Lactose is the natural sugar found in dairy products. Our bodies need an enzyme called lactase to digest it. If we do not produce enough lactase, that lactose moves through the gut undigested. This can lead to symptoms like bloating, tummy pain, loose stools, nausea and excess wind.

But why does this happen? And does it affect everyone the same way?

Can You Develop Lactose Intolerance Later in Life?

Yes, you absolutely can.

Lactose intolerance is not just something you are born with. It can develop gradually. In fact, most cases of primary lactose intolerance begin in later childhood, during the teenage years or in adulthood. This happens naturally as your body starts to produce less lactase over time.

For many people, the change is so slow they do not notice it at first. You might find that foods you once ate without issue now leave you feeling bloated or uncomfortable. That is completely normal.

It is also worth knowing that the ability to digest lactose varies depending on your genetics and cultural background. Some people continue to produce lactase throughout life, while others do not. Your body may simply be asking for a gentler approach.

Types of Lactose Intolerance

Once you understand how your body processes lactose, it becomes easier to figure out what kind of support it might need. There are two main types of lactose intolerance.

Primary Lactose Intolerance

This is the most common form. It is genetic and lifelong. After weaning (the transition from breastmilk or formula), our bodies naturally reduce lactase production. In many parts of the world, especially where dairy was not traditionally a part of the diet, this is completely normal.

Symptoms tend to appear gradually, often in the teenage years or adulthood, and they usually continue throughout life.

Secondary Lactose Intolerance

This form is different and often temporary.

Secondary lactose intolerance occurs when the lining of the small intestine becomes damaged. That damage can reduce lactase production. It might be triggered by a tummy bug, untreated coeliac disease, Crohn’s disease or even chemotherapy.

Unlike primary lactose intolerance, this type can improve. Once the gut lining heals, your ability to digest lactose may return.

How the Gut Microbiome Affects Dairy Digestion

This is where things become particularly interesting.

Your gut microbiome plays a big role in how you break down food. Some of these bacteria can help digest lactose, even if your own lactase levels are low.

A review of clinical trials found that probiotics (which are live, beneficial bacteria) can help reduce symptoms of lactose intolerance. Strains such as Lactobacillus and Bifidobacterium were shown to support digestion and ease discomfort after eating dairy.

You can take these as supplement, or you can find them naturally in fermented foods such as kefir, live yoghurt and sauerkraut.

That same study also highlighted the benefits of prebiotics, which are types of fibre that feed your helpful gut bacteria. Think of them as nourishment for your microbiome. Foods like onions, garlic, oats and bananas help maintain a healthy balance in your gut.

What This Means for You

If dairy has been making you feel uncomfortable, it does not necessarily mean you need to give it up completely. This is especially true if you are dealing with secondary lactose intolerance or milder symptoms.

Here are a few ways to work with your body:

• Try lactose-free dairy. It is still real milk, just without the lactose.
  

• Take it slowly. Many people can handle small amounts of lactose, especially when eaten with other food. 

• Include fermented dairy such as yoghurt or kefir that contain live bacteria.

• Consider probiotic supplements. Look for strains such as Lactobacillus acidophilus or Bifidobacterium longum, which have shown promise in clinical research.

• Add prebiotic foods to your meals. Onions, bananas, oats and garlic are all great options.
  
  

You might even try reintroducing small amounts of lactose gently over time. This gradual approach can help your microbiome adapt. It is known as colonic adaptation. Although it sounds technical, the idea is simple: your gut bacteria learn to support you more effectively.

Of course, everyone’s experience is different. Some people adjust quickly, while others need more time. If you believe you might have dairy intolerance, it is a good idea to speak with your GP or a registered dietitian.

References

Malik, T. F., & Panuganti, K. K. (2023). Lactose intolerance. In StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK532285/

Saiprasad, S. M., Moreno, O. G., & Savaiano, D. A. (2023). A narrative review of human clinical trials to improve lactose digestion and tolerance by feeding Bifidobacteria or galacto-oligosaccharides. Nutrients, 15(16), 3559. https://doi.org/10.3390/nu15163559

Szilagyi, A. (2015). Adaptation to lactose in lactase non persistent people: Effects on intolerance and the relationship between dairy food consumption and evaluation of diseases. Nutrients, 7(8), 6751–6779. https://doi.org/10.3390/nu7085309