Around one or two people out of every 100 in the UK have a food allergy, but food intolerance is more common.

Genuine food allergy is rare. About 2% of the population and 8% of children under the age of three are affected.

What is a food allergy?

A food allergy is a rapid and potentially serious response to a food by your immune system. It can trigger classic allergy symptoms such as a rash, wheezing and itching.

The most common food allergies among adults are to fish and shellfish and nuts, including peanuts, walnuts, hazelnuts and brazil nuts. Children often have allergies to milk and eggs as well as to peanuts, other nuts and fish.

What is a food intolerance?

Food intolerances are more common than food allergies. The symptoms of food intolerance tend to come on more slowly, often many hours after eating the problem food.

It’s possible to be intolerant to several different foods. This can make it difficult to identify which foods are causing the problem.

Food intolerances can also be difficult to tell apart from other digestive disorders that produce similar symptoms, such as inflammatory bowel disease, gastrointestinal obstructions or irritable bowel syndrome (IBS).

1. Sulfite intolerance

Sulfites are preservatives used in some drinks, foods and occasionally medication. Sulfites can cause allergy like reactions (intolerances), most commonly asthma symptoms in those with underlying asthma, sometimes allergic rhinitis (hay fever) like reactions, occasionally urticaria (hives) and very rarely, anaphylaxis (severe allergic reactions). Wheezing is the most common reaction.

2. Fructose or Sorbitol Intolerance

Fructose and sorbitol are two sugars that often are added to processed foods and medicines to make them taste sweet. Fructose can be found in soda pop and many fruit juice drinks. Sorbitol is found in diet products, chewing gum, candy, frozen ice treats, and some medicines (such as syrups for fevers and colds). Sometimes sorbitol and fructose are added to the same product. Gas, abdominal bloating and pain, and diarrhea are common symptoms of fructose or sorbitol intolerance.

3. Sucrose Intolerance

Many patients with GSID, also known as CSID, lack sucrase, the enzyme needed for sucrose digestion. An individual with GSID cannot digest sucrose, and therefore develops gastrointestinal (GI) symptoms after eating food containing sucrose. Many patients with GSID also have irregular amounts of the enzymes required for starch digestion (isomaltase, palatinase, maltase). These patients may experience gastrointestinal symptoms from starch consumption. The results are increased gas production and diarrhea. Symptoms may differ between infants, children, and adults.

4.Glucose and galactose malabsorption / intolerance

Glucose and galactose are two common sugars, which are present in many foods. They are found as free sugars, but also in combination with other sugars (e.g. sucrose – table sugar – is made up of glucose and fructose, lactose – milk sugar – is made up of glucose and galactose, maltose is made up of molecules of glucose). Typical symptoms are severe diarrhea leading to life-threatening dehydration, destabilization of the acidity of the blood and tissues (acidosis), stomach cramps, bloating, excess gas production, vomiting, and weight loss when fed breast milk or regular infant formulas.

5. MSG Allergy (Glutamate Intolerance)

Monosodium glutamate (MSG) is used as a flavor-enhancing food additive. It has a bad reputation because many believe it can cause allergy-like symptoms and side effects.

Those sensitive to MSG may experience:

headache;

hives;

runny nose or congestion;

mild chest pain;

flushing;

numbness or burning, especially in and around the mouth;

facial pressure or swelling;

sweating;

nausea;

digestive upset;

depression and mood swings;

fatigue.

More serious symptoms may include:

chest pain;

heart palpitations;

shortness of breath;

swelling in the throat;

anaphylaxis.

6. Wheat allergy/Gluten intolerance

A wheat allergy is an immune response to any of the proteins present in wheat, including but not limited to gluten. It’s most common in children. Around 65 percent of children with a wheat allergy outgrow it by the age of 12.

Symptoms of wheat allergy include:

nausea and vomiting;

diarrhea;

irritation of your mouth and throat;

hives and rash;

nasal congestion;

eye irritation;

difficulty breathing.

Symptoms related to a wheat allergy will usually begin within minutes of consuming the wheat. However, they can begin up to two hours after.

7. Histamine Intolerance

The symptoms of histamine intolerance (HIT) are caused by the inability of the body to break down histamine sufficiently. This is because of the reduced activity or presence of an enzyme called diamine oxidase (DAO), which is mainly responsible for breaking down histamine and other biogenic amines ingested through food.

Histamine plays a vital role for several of our body functions. We need a certain amount to live and function, but too much of it can cause painful symptoms involving the skin, the brain, lungs and heart and digestive system. The reactions are diverse and often look like or mimic the symptoms of an allergy.

8. Lactose Intolerance

Lactose intolerance means the body cannot easily digest lactose, a type of natural sugar found in milk and dairy products. This is not the same thing as a food allergy to milk.

When lactose moves through the large intestine (colon) without being properly digested, it can cause uncomfortable symptoms such as gas, belly pain, and bloating. Some people who have lactose intolerance cannot digest any milk products. Others can eat or drink small amounts of milk products or certain types of milk products without problems.