By Helen West

Food allergies are extremely common. In fact, they affect around 5 percent of adults and 8 percent of children—and these percentages are rising (1).

Interestingly, although it's possible for any food to cause an allergy, most food allergies are caused by just eight foods (2).

This article is a detailed review of the 8 most common food allergies. It discusses their symptoms, who is at risk and what you can do about it.

What Is a Food Allergy?

A food allergy is a condition in which certain foods trigger an abnormal immune response (2).

It's caused by your immune system wrongly recognizing some of the proteins in a food as harmful. Your body then launches a range of protective measures, including releasing chemicals like histamine, which causes inflammation.

For people who have a food allergy, even exposure to very small amounts of the problem food can cause an allergic reaction.

Symptoms can occur anywhere from a few minutes after exposure to a few hours later and they may include some of the following:

  • Swelling of the tongue, mouth or face
  • Difficulty breathing
  • Low blood pressure
  • Vomiting
  • Diarrhea
  • Hives
  • Itchy rash

In more severe cases, a food allergy can cause anaphylaxis. Symptoms, which can come on very quickly, include an itchy rash, swelling of the throat or tongue, shortness of breath and low blood pressure. Some cases can be fatal (3).

Many food intolerances are often mistaken for food allergies.

However, food intolerances never involve the immune system. This means that while they can severely impact your quality of life, they are not life threatening.

True food allergies can be divided into two main types: IgE antibody or non-IgE antibody. Antibodies are a type of blood protein used by your immune system to recognize and fight infection (4).

In an IgE food allergy, the IgE antibody is released by your immune system. In a non-IgE food allergy, IgE antibodies aren't released and other parts of the immune system are used to fight the perceived threat.

Here are the eight most common food allergies.

1. Cow's Milk

An allergy to cow's milk is most often seen in babies and young children, especially when they have been exposed to cow's milk protein before they are six months old (5, 6).

It's one of the most common childhood allergies, affecting 2–3 percent of babies and toddlers (7).

However, around 90 percent of children will outgrow the condition by the time they're three, making it much less common in adults.

A cow's milk allergy can occur in both IgE and non-IgE forms, but IgE cow milk allergies are the most common and potentially the most serious.

Children or adults with an IgE allergy tend to have a reaction within 5–30 minutes of ingesting cow's milk. They experience symptoms like swelling, rashes, hives, vomiting and, in rare cases, anaphylaxis.

A non-IgE allergy usually has more gut-based symptoms like vomiting, constipation or diarrhea, as well as inflammation of the gut wall (6).

A non-IgE milk allergy can be quite difficult to diagnose. This is because sometimes the symptoms can suggest an intolerance and there is no blood test for it (8).

If a diagnosis of a cow's milk allergy is made, the only treatment is to avoid cow's milk and foods that contain it. This includes any foods or drinks that contain:

  • Milk
  • Milk powder
  • Cheese
  • Butter
  • Margarine
  • Yogurt
  • Cream
  • Ice cream

Breastfeeding mothers of babies with an allergy may also have to remove cow's milk and foods that contain it from their own diets.

As for babies who aren't breastfeeding, a suitable alternative to a cow's milk-based formula will be recommended by a health professional (9).

Summary: A cow's milk allergy mostly affects children under the age of three. A diagnosis of cow's milk allergy means that all milk and milk products must be avoided.

2. Eggs

An egg allergy is the second most common cause of food allergy in children (10, 11).

However, 68 percent of children who are allergic to eggs will outgrow their allergy by the time they're 16 (12).

Symptoms include:

  • Digestive distress, such as a stomach ache
  • Skin reactions, such as hives or a rash
  • Respiratory problems
  • Anaphylaxis (which is rare)

Interestingly, it's possible to be allergic to egg whites, but not the yolks and vice versa. This is because the proteins in egg whites and egg yolks differ slightly.

Yet most of the proteins that trigger an allergy are found in egg whites, so an egg white allergy is more common (11).

Like other allergies, the treatment for an egg allergy is an egg-free diet (13).

However, you may not have to avoid all egg-related foods, as heating eggs can change the shape of the allergy-causing proteins. This can stop your body from seeing them as harmful, meaning they're less likely to cause a reaction (14, 15, 16).

In fact, one study found that around 70 percent of children with an egg allergy could tolerate eating biscuits or cakes containing a cooked egg component (17).

Some studies have also shown that introducing baked goods to children with an egg allergy can shorten the time it takes for them to outgrow the condition (18).

Nevertheless, this isn't the case for everybody and the consequences of ingesting eggs when you are allergic to them can be severe. Because of this, you should check with your doctor before you reintroduce any egg-containing foods.

Summary: The most common type of egg allergy is an egg white allergy. The treatment is an egg-free diet. However, some people may be able to reintroduce some foods containing cooked eggs into their diet.

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