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Food allergy or intolerance – what’s the difference?

Allergic reaction and intolerance to food result in two different types of physical body responses; one involves the immune system and the other doesn’t. Here’s what you need to know.

One small thing: Whether you have a food allergy or an intolerance, it is recommended that you meet with a registered dietitian to help you plan your restricted diet. When you cut certain foods from your diet, you may need help planning the inclusion of others so as not to short-change yourself with important vitamins and minerals.

When a food-hypersensitivity reaction involves your immune system, it’s called a food allergy; when it doesn’t involve the immune system, it’s called a food intolerance. Diagnosis of either a food allergy or intolerance should involve appropriate testing in order to avoid unnecessary elimination diets that could put you at risk of nutritional deficiencies.

Food allergies

A food allergy happens when your immune system reacts to a substance in a food (usually a protein) that your body sees as harmful. Symptoms can occur within minutes and can be mild, such as a runny nose or itchy eyes, or severe and even life-threatening.

When your immune system reacts in this way to a food protein, Immunoglobulin E (IgE) antibodies are created, which are specific for that particular protein. When you eat foods containing this protein again, the antibodies recognise it and link to it, causing the release of substances, such as histamine, which cause the allergic symptoms.

If you experience an allergic reaction, you may have a combination of the following signs and symptoms, ranging from mild to severe, which can affect your entire body:

  • Skin: hives, flushed skin or rash, swelling of the face, lips and/or tongue, and itching
  • Respiratory: coughing or wheezing, shortness of breath, chest pain or tightness, throat tightness, hoarse voice, nasal congestion or hay fever-like symptoms (runny, itchy nose and watery eyes, sneezing) and/or trouble swallowing
  • Gastrointestinal: nausea, abdominal pain or cramps, vomiting and/or diarrhoea
  • Cardiovascular: paler than normal skin colour/blue skin colour, weak pulse, dizziness or light-headedness, loss of consciousness and/or shock
  • Other: anxiety, headache, uterine cramps and/or a metallic taste in the mouth

The most dangerous allergic reaction is called anaphylaxis and symptoms include breathing difficulties, a drop in blood pressure or shock, which can result in a loss of consciousness and even death.

8 common food allergens

There are more than 170 foods that are known to cause food allergies. However, eight foods account for 90% of all food-allergic reactions. These include:

  • 1. Milk
  • 2. Egg
  • 3. Peanuts
  • 4. Tree nuts, for example walnuts and cashews
  • 5. Fish, for example salmon, cod, tuna, snapper, eel and tilapia
  • 6. Shellfish, for example, prawns, shrimps, lobster and crab
  • 7. Soya
  • 8. Wheat
Food intolerance

A food intolerance arises when your body is unable to digest a certain component of a food, such as lactose or gluten. Although symptoms of a food intolerance are unpleasant, they are not life-threatening and often affect the digestive and respiratory systems and skin. Common symptoms include:

  • • Skin: flushed skin or a rash
  • • Respiratory: runny nose
  • • Gastrointestinal: bloating, nausea, abdominal pain, reflux and/or diarrhoea
  • • Other: headaches and/or fatigue

Food or components of food that can cause these symptoms include:

  • Dairy
  • Gluten
  • Caffeine
  • FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols)
  • Sulphides
  • Fructose
  • Yeast
  • Food colouring
  • MSG
Special precautions

If you eat something and notice a reaction, it’s important to see your doctor who will be able to determine whether you have a food intolerance or allergy.

Protect yourself from food allergies and intolerance

At PnP, we’re committed to ensuring transparent and accurate labelling of products that is in line with the South African regulations for food labelling and advertising. We work hard to ensure that our food labelling is clear and concise. Our own brand products provide detailed information, and where an allergen is present in a product, it’s highlighted in bold behind the respective ingredient in the ingredients list. Alternatively, our food labels call out all the allergens contained in a product under a section called “allergens” on the product label.

If you have a question for our dietitians, click here, or to find a dietitian in your area, visit To get in touch with us, email