What's the Difference? Lactose Intolerance, Sensitivity and Dairy Allergy

There tends to be a lot of confusion when it comes to digestive concerns and dairy products.

Let’s distinguish the differences between lactose intolerance, which is a type of carbohydrate intolerance, lactose sensitivity for patients with IBS, and finally, dairy allergy.‍‍

What is a Lactose Intolerance?

Lactose intolerance is a type of carbohydrate intolerance to the main sugar found in milk, lactose. For people with lactose intolerance, the cells on the lining of the small intestine are not producing enough of the enzyme lactase, which is needed to break down lactose.

Without enough of the enzyme lactase, lactose travels through the GI tract undigested, leading to some uncomfortable symptoms in the process.¹ These symptoms tend to appear very soon after eating a lactose-containing food  - often within 30 minutes.

Symptoms can be managed by avoiding lactose-containing foods and taking an over-the-counter enzyme, such as Lactaid, prior to eating a food containing lactose.¹

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Lactose & IBS

Lactose as it relates to a low FODMAP diet and patients with IBS is not the same as lactose intolerance, though interestingly enough a lot of patients with IBS may also have lactose intolerance. Patients with IBS have what’s called a functional bowel disorder and can experience symptoms due to a variety of variables, including experiencing higher levels of stress, lack of sleep, and how certain foods impact digestion.²

Not all patients with IBS will have a sensitivity to lactose, but many often do. For those without a known history of lactose intolerance, a trial elimination and reintroduction of lactose-containing foods (via a Low FODMAP diet) is the best way to tell if lactose is a trigger food. It’s possible some foods can be tolerated, and smaller amounts may be best. 

What is a dairy allergy?

A dairy allergy is actually pretty rare in adults compared to the previous two and is fundamentally different. Having an allergy to dairy is based on the body’s immune system response (IgE antibodies) to the protein in dairy.³ Your body sees dairy as a threat and reacts accordingly.

It’s also possible that some symptoms related to a dairy allergy are not GI specific, such as hives, itching, and in severe cases, anaphylaxis.³ If you suspect you may have a dairy allergy, avoidance is typically recommended. Nevertheless, it’s best to consult with a board-certified allergist to understand the best next steps.  

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Do you have lactose intolerance, or have issues tolerating lactose as identified by the low FODMAP diet?

Check out this article for lactose-free or low-lactose substitutions. In addition, feel free to utilize the resources below for more information on lactose intolerance, sensitivities and dairy allergies.

• Causes and diagnosis of lactose intolerance
• Definition & facts for lactose intolerance
• The Facts About Dairy Allergy

Sources

1. Misselwitz B, Butter M, Verbeke K, Fox MR. Update on lactose malabsorption and intolerance: pathogenesis, diagnosis and clinical management. Gut. 2019;68(11):2080-2091. doi:10.1136/gutjnl-2019-318404
2. Cancarevic I, Rehman M, Iskander B, Lalani S, Malik BH. Is There a Correlation Between Irritable Bowel Syndrome and Lactose Intolerance?. Cureus. 2020;12(1):e6710. Published 2020 Jan 20. doi:10.7759/cureus.6710
3. Flom JD, Sicherer SH. Epidemiology of Cow's Milk Allergy. Nutrients. 2019;11(5):1051. Published 2019 May 10. doi:10.3390/nu11051051

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