Why can't celiacs have dairy? The crucial connection between gluten damage and lactose intolerance

October 4, 2025 •

4 min read

According to Beyond Celiac, secondary lactose intolerance is very common in newly diagnosed celiac disease patients. This occurs because the intestinal damage caused by gluten affects the body's ability to produce the enzyme needed to digest milk sugar, explaining why many celiacs initially struggle with dairy.

Quick Summary

Damage to the small intestine from celiac disease can cause temporary lactase deficiency, leading to lactose intolerance. Following a strict gluten-free diet often allows the gut to heal, potentially restoring the ability to digest dairy over time, though some may also have a separate milk protein sensitivity.

Key Points

Secondary Lactose Intolerance: The primary reason celiacs initially struggle with dairy is a temporary lack of the lactase enzyme, caused by gluten-induced damage to the small intestine.
Healing Restores Tolerance: As the small intestine heals on a strict gluten-free diet, lactase production can return to normal, allowing many individuals to tolerate dairy again over time.
Not a Milk Allergy: This is an intolerance to milk sugar (lactose), not an allergic immune response to dairy proteins, though a separate milk protein sensitivity can exist.
Overlap of Symptoms: Symptoms like bloating, gas, and diarrhea are common to both untreated celiac disease and lactose intolerance, which can be confusing prior to diagnosis.
Cautious Reintroduction: Dairy should be reintroduced slowly and carefully after the gut has healed, starting with low-lactose options like hard cheese and yogurt.
Consider Milk Protein Sensitivity: If digestive symptoms persist even after healing, the issue may be a sensitivity to milk proteins like casein or whey, which is a separate condition.
Nutritional Awareness: Individuals avoiding dairy must ensure they get enough calcium and vitamin D from fortified non-dairy foods or supplements to support bone health.

The Root Cause: Secondary Lactose Intolerance

The primary reason a person with celiac disease might temporarily experience issues with dairy is a condition called secondary lactose intolerance. Celiac disease is an autoimmune disorder where the ingestion of gluten triggers an immune response that damages the lining of the small intestine. The finger-like projections in the small intestine, known as villi, become flattened and damaged. These villi are where the enzyme lactase is produced. Lactase is necessary to break down lactose, the sugar found in milk and dairy products. When the villi are damaged, the body can't produce enough lactase, leading to lactose malabsorption and the resulting symptoms of intolerance.

Symptoms of lactose intolerance can be very similar to those of celiac disease, including bloating, gas, abdominal pain, and diarrhea. This overlap can make it difficult for an individual to distinguish which food is causing their discomfort before a celiac diagnosis is made. Because the intolerance is a secondary effect of the intestinal damage, it is not a direct immune reaction to dairy itself, unlike a true milk allergy.

The Path to Recovery: Is Dairy Intolerance Always Temporary?

For most people with celiac disease, the lactose intolerance is a temporary condition that improves as the small intestine heals on a strict gluten-free diet. As the villi recover, the body can once again produce sufficient lactase to digest dairy. The time it takes for tolerance to return can vary significantly from person to person, ranging from a few months to a couple of years.

However, it is not always a guarantee that dairy tolerance will return fully. Some people with celiac disease may have an underlying, unrelated lactose intolerance due to age or genetics that is not temporary. Additionally, a distinct issue can exist: milk protein sensitivity, which is different from lactose intolerance. This sensitivity involves a reaction to proteins like casein or whey, not the lactose sugar. If symptoms persist despite a lactose-free diet and gut healing, a milk protein sensitivity might be the culprit.

Reintroducing Dairy Safely

For those who suspect their lactose intolerance is temporary, reintroducing dairy should be done cautiously after the gut has had time to heal. Starting with small amounts of dairy and observing your body's reaction is key. A structured reintroduction can help you pinpoint your personal tolerance level.

Tips for safe reintroduction:

Start small: Begin with a quarter or half cup of a lower-lactose dairy product and consume it with a meal, not on an empty stomach, to aid digestion.
Choose wisely: Opt for hard, aged cheeses (like cheddar, Parmesan, and Swiss) or yogurt first, as they contain less lactose.
Monitor symptoms: Keep a food diary to track your intake and any resulting symptoms. This helps differentiate between lactose issues and potential milk protein sensitivity.
Use alternatives: Lactose-free milk, fortified plant-based milks, and lactase enzyme supplements can help manage symptoms during this phase.

The Importance of Dairy-Free Nutrition

For those who must remain dairy-free, ensuring adequate intake of calcium and vitamin D is crucial for bone health, especially given that celiac disease can already cause malabsorption of these nutrients. It is essential to incorporate calcium-rich non-dairy foods and potentially consider supplements under a doctor's supervision.

Non-dairy sources of calcium include:

Fortified plant-based milks (almond, soy, rice)
Leafy green vegetables (kale, spinach, broccoli)
Fish with soft, edible bones (salmon, sardines)
Tofu and fortified orange juice
Sesame seeds

Lactose Intolerance vs. Milk Protein Sensitivity


Feature	Secondary Lactose Intolerance	Milk Protein Sensitivity (Casein/Whey)
Cause	Temporary deficiency of lactase enzyme due to intestinal damage from celiac disease.	Reaction to casein or whey proteins, a distinct issue from lactose intolerance.
Symptom Trigger	Ingestion of lactose, the sugar in dairy products.	Ingestion of dairy proteins (casein and whey), regardless of lactose content.
Intestinal Damage	Does not cause intestinal damage itself, unlike gluten.	Some studies suggest ongoing intestinal damage or celiac-like symptoms in some children with both conditions.
Permanence	Often temporary and may resolve with a strict gluten-free diet as the gut heals.	Can be a permanent issue requiring long-term dairy avoidance.
Reintroduction	Can often be reintroduced gradually over time.	May not be able to tolerate dairy at all, even in aged cheeses.

Conclusion

In summary, the reason many celiacs can't have dairy is not a direct consequence of the autoimmune disease but rather a temporary effect of the intestinal damage it causes. The inability to produce the lactase enzyme leads to secondary lactose intolerance, resulting in similar digestive symptoms to celiac disease. The good news is that for many, this is a reversible condition that improves as the small intestine heals on a gluten-free diet. However, it is important to also consider other possibilities like a persistent milk protein sensitivity. With careful reintroduction and management, including finding alternative calcium sources, many people with celiac disease can navigate their relationship with dairy safely. As always, consulting a healthcare provider or registered dietitian is recommended to create a personalized plan. For more information on navigating life with celiac disease, visit Beyond Celiac.

Frequently Asked Questions

Yes, people with celiac disease often can have dairy. However, many newly diagnosed celiacs experience temporary lactose intolerance due to intestinal damage from gluten. As their small intestine heals on a gluten-free diet, they are often able to reintroduce dairy.

Untreated celiac disease damages the small intestine's villi, which produce the enzyme lactase needed to digest lactose. This damage leads to a temporary lactase deficiency, resulting in secondary lactose intolerance until the gut heals.

The intolerance is likely temporary if symptoms improve as your small intestine heals on a strict gluten-free diet. If you are still experiencing symptoms after several months of healing, you may have a permanent intolerance to lactose or a separate milk protein sensitivity.

After several months on a gluten-free diet, start by reintroducing low-lactose dairy products like hard cheeses or yogurt in small amounts. Gradually increase the amount and try other dairy products while monitoring your symptoms. Using a food diary can be helpful.

A milk protein sensitivity is a separate issue from lactose intolerance and may cause persistent symptoms even with low-lactose dairy. In this case, you may need to avoid dairy entirely, as you are reacting to the casein or whey proteins.

If you need to avoid dairy, you can get calcium from fortified non-dairy milks (almond, soy, rice), leafy greens like kale and spinach, fortified orange juice, and bony fish like salmon and sardines. Discuss your nutritional needs with a doctor or dietitian.

Lactose intolerance is not a milk allergy. A true milk allergy is an immune system response that can cause severe reactions. While some celiacs may also have a milk protein sensitivity, it is distinct from a life-threatening allergy. Discuss any severe reactions with your doctor immediately.

Hard, aged cheeses (cheddar, Parmesan, Swiss), yogurt (especially Greek yogurt), and lactose-free milks are typically easier to digest and good options for starting dairy reintroduction.