Say Cheese! The 3-step lactose challenge & 4 science-backed strategies for managing an intolerance

Have you ever heard that cutting out certain foods is the key to optimal gut health? Gluten, dairy, and sugar have all been in the spotlight of restrictive trends over the years. But for most of us, restriction isn’t the answer—your gut microbes thrive on variety, after all.

When it comes to managing certain food intolerances, though a restrictive approach might be even more tempting and historically even recommended, especially if you’re dealing with uncomfortable symptoms like bloating, cramps, or diarrhoea. But here’s the good news: for certain types, such as lactose intolerance, with a few science-backed strategies, most people don’t need to eliminate them entirely.

Let’s explore the important differences between allergies and intolerance, and how to identify lactose intolerance with our simple at-home testing protocol. Most importantly, find out how you can still have your (lactose-containing) cake and eat it too.

What’s the difference between an allergy and an intolerance?

While both food allergies and intolerances are types of hypersensitivity, they’re not the same and need different approaches. Food allergies involve the immune system, which mistakenly sees certain foods as threats. Symptoms can be severe—like difficulty breathing or a racing heart—and require complete avoidance. Allergies affect around 1–2% of adults and should be diagnosed only by a qualified clinician. If you suspect an allergy, consult an allergy-specialist dietitian or an allergist before making any changes. Intolerances, on the other hand, don’t involve the immune system and are often due to a lack of certain digestive enzymes, as in the case of lactose intolerance.

What is lactose intolerance?

Lactose, the natural sugar found in many dairy foods, needs to be broken down into two simple sugars before your gut can absorb it. This breakdown happens with the help of an enzyme called lactase, found in the small intestine. Many people produce less lactase than they need, which can lead to lactose intolerance. When lactose isn’t absorbed properly, uncomfortable gut symptoms can kick in, such as bloating, altered bowel movements, cramping, etc. This is surprisingly common in certain populations: up to 90% of people in Asian, African, and Caribbean populations are affected, compared to only about 5% in northern regions.

We know that there are two main types of lactose intolerance:

• Primary: This common type is inherited and usually starts anywhere between the ages of five and 20 when lactase production decreases naturally (in certain populations).
• Secondary: This type can develop after illness or damage to the small intestine, like after gut infections, periods of gut inflammation, if you have undiagnosed coeliac disease, or active Crohn’s disease. The good news? It’s often temporary, and lactase levels can return to normal after three to six months of healing.

Test your intolerance – take the 3-step lactose challenge

So you suspect you have lactose intolerance because every time you enjoy a latte, creamy pasta or ice cream, your gut tells you it isn’t happy. If you’re struggling with waiting lists or would rather play food detective at home, put down Dr Google and take this lactose challenge to help determine whether lactose really is the culprit. Aim to do this blinded, which, in research speak, means that you are unaware if you are having the lactose-containing product or a placebo (i.e., a matched food that doesn’t contain lactose). This comes back to the gut:brain axis. Remember: the communication between the two is bidirectional, which explains why if we perceive something to be bad for us (even if it’s not), it can actually manifest in physical gut symptoms. Blinding a food challenge removes this type of bias.

Step 1. 48 hours prior to each challenge 

Swap all lactose-containing foods for low lactose foods**. Following a low lactose diet for 48 hours prior to and during the challenge will ensure your trial is more accurate.

Step 2. To prepare, you will need:

• 400mls of low fat cow’s milk (active challenge).
• 400mls of low fat lactose-free cow’s milk (placebo challenge).
• A loved one or friend. They will be in charge of blinding you to the different challenges. Ask them to disguise the milk so you can’t tell the difference between the active and the placebo.

Step 3. Begin the challenge:

• Test your milks one week apart, on the same day and ideally at the same time. So, if you choose a Wednesday evening for the first challenge, stick to the following Wednesday evening for the second challenge. This will help keep the testing conditions the same.
• Remember to continue on a low lactose diet during and for 24 hours following the challenge.

**Check out this comprehensive lactose resource for more tips on completing this lactose challenge (including a detailed list of what foods contain lactose) and managing your intolerance.

Can you tolerate it?

While intolerances can be uncomfortable if you consume too much of certain foods, because they don’t involve the immune system, most people can often still enjoy some without symptoms. Despite this, it’s common for people to become hypervigilant of certain foods after suspecting an intolerance—especially if they’ve relied on online intolerance tests, which are unfortunately unreliable. In fact, even when you have an accurately diagnosed intolerance, like lactose, for example, avoiding lactose completely might actually do more harm than good. More specifically, doing so can reduce your tolerance further over time, meaning symptoms become worse even after small amounts. This can make it harder to manage when eating out, which anyone with a food intolerance will know can take the fun out of dining with friends and family.

As we touched on above, the good news is that most people with lactose intolerance can still enjoy small portions of lactose spread throughout the day without symptoms. For example, around 3g of lactose per meal (about 70ml of milk) with up to 3 sittings per day is often well tolerated e.g totalling 12g per day. With time, you may even be able to increase this threshold by following these tips: