by Deborah Lynn Blumberg April 19, 2021 4 min read

According to worldwide testing and research, a dairy allergy or intolerance is the most common food sensitivity. Despite this, many people who are sensitive to dairy are not aware of it.

When people are unable to digest the sugar in cow's milk (known as lactose), this is considered an intolerance. When people have a reaction to the proteins in cow's milk, this is considered an allergy. Both are widespread: In the United States, an estimated 30 to 50 million adults are believed to be lactose intolerant, while research has shown a milk allergy affects half of the food-allergic kids under age 1.

Lactose intolerance presents itself primarily through digestive issues such as bloating, gas and diarrhea. But a dairy allergy can often be hard to identify. Consuming dairy when you're allergic to it, can trigger an unhealthy inflammatory response, which can lead to several issues such as mucus congestion in the sinuses and skin conditions like acne and eczema. Here's a breakdown of the types of allergic reactions to dairy, common signs and symptoms, and what you can do if you're concerned you may have a dairy allergy.

Types of Allergic Reactions to Dairy

If you have a dairy allergy, this means your immune system overreacts to casein and whey, the specific proteins found in cow's milk. But not all allergies are the same. There are two types of allergic reactions to dairy: IgE and IgG. Both involve the immune system.

IgE reaction

An IgE reaction is immediate and obvious, classified as a type I allergy. When some people eat yogurt or drink a glass of milk, within minutes their body produces an antibody called immunoglobulin E, or IgE, to attack the proteins, which it sees as foreign invaders. These antibodies activate immune cells to release a chemical called histamine. This can cause swelling, breathing difficulties, skin flare-ups (such as hives), or even anaphylactic shock, which is a life-threatening allergic response requiring immediate medical attention during which a person's airway narrows, blocking their ability to breathe and causing a sudden drop in blood pressure.

IgG reaction

Others can have what's known as an IgG reaction, which is less immediate — sometimes taking hours or days to appear. Known as a type III allergy, this is when the immune system produces an antibody called immunoglobulin G, or IgE, leading to inflammation. Some symptoms can be difficult to identify, seeing as you may not associate your discomfort with something you ate up to three days ago. These might include:

  1. Skin reactions: Some people may experience acne or eczema after consuming dairy. The cause might be mistaken for dryness or breakouts but is, in fact, the body's response to dairy.
  2. Sinus issues: Dairy products can also lead to congestion, sinus pressure and thickened mucus. You might attribute your discomfort to seasonal allergies or a mild cold, but it could be a sensitivity to milk.
  3. Gut issues: Some experience diarrhea, gas or bloating after consuming dairy products. Dairy can also affect the gut by inducing nausea or vomiting that could be confused with food poisoning or a stomach bug.
  4. Chronic inflammation: If you're allergic to dairy and your immune system becomes overworked, you might experience chronic inflammation. Signs include unexplained fatigue, body or joint pain, and low energy. Chronic inflammation means your body is in a constant state of alert. This can ultimately be harmful to your body's organs and tissues.

Common and Hidden Dairy Sources

Obvious sources of dairy include cow's milk and cheese, but dairy is often an ingredient in a host of other foods, including chocolate, breaded foods (often dipped in milk) and packaged foods, like cookies or butter-flavored popcorn.

Other potential hidden sources of dairy include equipment like deli slicers, which are used to cut both meat and cheese, and ice cream scoopers, which are often used to serve both dairy and non-dairy ice creams at ice cream shops.

Alleviating Symptoms

The best way to determine if you are reacting to certain foods is through a simple at home food sensitivity test. Simply reducing or eliminating dairy from your diet can also results in many benefits. You could try an elimination diet, removing dairy from your diet for a period of time. Then, reintroduce these products, and take note of any issues that might pop up. If symptoms reappear, it's a good sign that you may be allergic to dairy or have a sensitivity.

After removing dairy from their diet, some people find they have noticeably clearer skin, especially if their hives or eczema have cleared up. Others might find relief from ongoing joint pain, see an improvement in their problematic sinus issues or realize they no longer experience lower energy or fatigue.

Dairy alternatives can help you keep allergies at bay without sacrificing taste. Plant milk (which also has 50% more calcium) is a good substitute, including almond or coconut milk. Some people who have a problem with cow's milk products may tolderate goat or sheep milk alternatives — or even ghee, which is clarified butter that doesn't contain casein or lactose (the components of cow's milk people often react to).



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