Welcome back to my FODMAP Explained series! In this set of articles, I break down the acronym FODMAP and share practical tips to help you reduce digestive symptoms while still enjoying the widest variety of foods possible. In this post, we’re focusing on the letter “D,” which stands for Disaccharides, specifically, lactose.
As a registered dietitian specializing in IBS and the low FODMAP diet, my goal is to make this diet easy to understand and apply without unnecessary restrictions.
The “D” in FODMAP: Disaccharides (Lactose)
Disaccharides are sugars made up of two sugar molecules joined together. In the low FODMAP diet, the main disaccharide of concern is lactose.
Lactose is the natural sugar found in milk and dairy products.
Why Is Lactose a FODMAP?
To digest lactose properly, your body needs an enzyme called lactase, which breaks lactose down into its two smaller sugars: glucose and galactose.
Some people do not produce enough lactase, which means lactose is not fully digested in the small intestine. Instead, it travels to the large intestine, where gut bacteria ferment it.
This fermentation can lead to symptoms such as:
- Bloating
- Excess gas
- Abdominal pain
- Diarrhea or loose stools
This is why lactose is considered a FODMAP trigger for many people with IBS.
Is the Low FODMAP Diet Dairy-Free?
One of the most common misconceptions is that the low FODMAP diet is completely dairy-free.
It’s not!
The low FODMAP diet is actually a low-lactose diet, not a dairy-free diet. This means many people can still enjoy certain dairy products, especially those that are naturally low in lactose or lactose-free.
Examples include:
- Aged cheeses
- Lactose-free milk
- Lactose-free yogurt
- Butter and cream (in small amounts)
For the most up-to-date information on the lactose content of foods, the Monash FODMAP App is your best resource.
For a deeper look at how to incorporate dairy into a low FODMAP diet, read my full guide here: Can You Have Dairy on a Low FODMAP Diet? Discover the Surprising Truth About Dairy and FODMAPs!
How Much Lactose Can You Tolerate?
Interestingly, many people with lactose intolerance can still tolerate small amounts of lactose without symptoms.
Many people may tolerate up to about 1 cup (240 mL) of milk, while others may tolerate less (or more!). Everyone’s tolerance is different, which is why the reintroduction phase of the low FODMAP diet is so important.
This phase helps you identify your personal tolerance level so you can avoid unnecessary food restrictions.
Don’t Forget About Calcium
Including some dairy products during the low FODMAP diet can help improve variety and make it easier to meet your calcium needs.
If you avoid dairy due to lactose intolerance, a milk allergy, or a vegan lifestyle, there are still many good calcium sources available, including:
- Fortified non-dairy milks
- Legumes
- Certain vegetables
- Nuts and seeds
- Calcium-set tofu
The goal is always to create the most varied and nutritionally balanced diet possible.
FODMAP Lactose Explained: It’s a Wrap!
Lactose is the main disaccharide in the FODMAP acronym and can be a common trigger for digestive symptoms in people with IBS.
The good news? Following a low FODMAP diet does not mean giving up dairy completely.
During the elimination phase, it is possible to eat low-lactose or lactose-free dairy products. After that, many people discover during reintroduction that they can tolerate lactose in small amounts – or even fully reintroduce it without issues. And for those who remain sensitive, lactose-free products or lactase enzyme supplements can make dairy much easier to enjoy.
The goal is not long-term restriction: it’s finding what works best for your body.
If you’re feeling overwhelmed with what to eat, don’t go it alone. As a registered dietitian specializing in IBS and the low FODMAP diet, I’m here to help you build a personalized, sustainable plan that works for your life.
You can find out how I can help you get relief from uncomfortable gut symptoms and design a diet that works for you by booking your complimentary IBS Clarity Session.
We will review your symptoms and history and discuss the best next steps for you! You will come out of this call feeling relieved and hopeful that you can take control of your IBS.
Want to learn more?
Check out more Low FODMAP Diet Basics
Antonella Dewell, MS, RDN | IBS Resolution Expert
Antonella Dewell is a registered dietitian and IBS specialist based in California. She has over 2 decades of experience working in clinical research at Stanford. Since 2018, she has been running a private practice. She helps people with IBS gain real, lasting relief from IBS symptoms in just 2-4 weeks without giving up all the foods they love, so they can stop feeling anxious around food and get back to fully enjoying food and life again.
