You and Your Health: Food allergies vs intolerance

With Andrew Watson of Goodmeasure Pharmacy, Rotherham

They say eating good food makes life good. But if you suffer with a food hypersensitivity then the simple act of fuelling your body can become less than enjoyable.

The bowel is a sensitive organ, so it’s no surprise that a fifth of adults in the UK have experienced a reaction to food, such as an allergy or intolerance. While the symptoms of each may overlap, making it difficult to distinguish between them, the difference in severity can be hard to stomach.

But what is the difference between being allergic to a food, or having an intolerance to it? Biologically it’s a case of immune system versus digestive system.

Food allergies

A food allergy occurs when the immune system mistakes harmless protein in foods as a threat, releasing chemicals such as histamine to kill it.

Around two percent of adults have a food allergy and this has risen sharply over the last few decades; most people will be diagnosed with a food allergy before their third birthday, but it can develop at any age.

The reason is uncertain, but people with a food allergy will usually have other allergies such as eczema, hay fever or asthma. Family history may also increase the risk, although the allergen may differ. Some correlate the change in children’s diets over the last 40 years to the rise in allergies, as well as germ-free environments meaning immune systems aren’t exposed to as many threats.

Any foods can cause an allergy, but more common allergens include cow’s milk, eggs, peanuts, tree nuts, fish, shellfish and certain fruits and vegetables such as celery and soybeans.

Reactions usually happen immediately after coming into contact with the trigger – either through eating, touching or inhaling. This may be a mild reaction, or more serious such as anaphylaxis which can be a life-threatening medical emergency.

Symptoms of allergic reactions include:

  • Itchy mouth, throat or ears
  • Hives
  • Swelling of the face, eyes, lips or tongue
  • Vomiting or diarrhoea
  • Hay fever life symptoms 

Mild to moderate symptoms will usually subside with an antihistamine which can be bought over the counter from your local pharmacy. Make sure you purchase non-drowsy.

More severe signs of anaphylaxis include breathing difficulties, trouble swallowing, feeling faint, or collapse. You should call 999 immediately in these instances if you suspect anaphylaxis as adrenaline will need to be administered.

Living with a food allergy means great care and attention must be taken regarding diet, especially when you eat out or buy pre-packaged food. Under EU law, all 14 common allergens must be highlighted on food packaging. For foods sold without packaging such as in a bakery, café or pub, allergen information must be provided either in writing or verbally.

Food intolerance

Contrastingly, food intolerance is when the body has difficulty digesting certain foods, leading to an unpleasant but mild reaction. Food intolerances are not life-threatening as they don’t involve the immune system. The onset of symptoms may be gradual and only occur if you eat a substantial amount of food.

Symptoms of food intolerance include:

  • Bloating
  • Tummy pain
  • Excessive wind
  • Diarrhoea
  • Mild rashes

More common food intolerances include dairy, gluten, caffeine, and additives and preservatives such as MGM, sulphites, and artificial colours. Other triggers may include red wine, cheese, and salicylates which are found in certain vegetables, herbs, spices, fruits and chocolate.

What about coeliac disease?

Coeliac disease is neither an intolerance nor an allergy. It is an autoimmune disorder where the bowel’s surface becomes damaged from an adverse reaction to gluten. This results in the body not getting enough nutrients, thus increasing the risk of osteoporosis and anaemia.

Symptoms of coeliac disease include:

  • Diarrhoea
  • Stomach ache
  • Bloating
  • Indigestion
  • Constipation
  • Fatigue
  • Unexplained weight loss
  • Rashes

One percent of people are coeliac and risk increases if you have conditions such as type 1 diabetes, thyroid problems or Down’s syndrome. It usually develops between eight and 12 months or aged 40-60. Gluten is found in wheat, barley and rye so people with coeliac disease need to make changes to their diet to prevent long-term complications. Foods like pasta, cakes, cereals, bread, sauces and even beers will need to cut out or be gluten-free alternatives.

When to seek medical advice?

If you suspect you or your child has food hypersensitivity, always seek medical advice. If you diagnose yourself, you may cut certain foods out of your diet that are safe and nutritious while at the same time continuing to include foods that may be risky.

Your GP will look at your medical and family history, as well as any symptoms that have presented. Because symptoms mimic other digestive conditions such as IBS and inflammatory bowel disease, definitive diagnosis can be difficult. However, you may be advised to complete a food diary to track if any symptoms arise after eating. Other tests may include an elimination diet where you exclude certain food groups from your diet one at a time for two to six weeks before reintroducing them to observe any effects.

If allergies are likely, you may be referred to an allergy clinic for further tests. It is always advised you avoid shop-bought allergy or intolerance tests as they are expensive, unreliable and not scientifically proven. Private companies claim to be able to diagnose allergies and intolerances by testing muscle responses, electrical conductance of the skin, and energy fields around the hair.