How can you determine whether one has an allergy or intolerance towards certain foods? Dr Stephen Lee, Specialist in ENT Surgery, Raffles ENT Centre, clarifies the difference between these rather similar yet different conditions.
What is Food Allergy?
- Food allergy refers to the classical immunological mediated response to food ingested which triggers an immune system reaction that affects numerous organs in the body.
- This is well established through an antibody, called IgE, to the specific offending food.
What are the signs?
- The reactions usually occur within minutes and up to two hours after ingestion.
- It can be triggered by ingesting even miniscule amounts of food that is usually eaten infrequently.
- The reactions tend to be consistent each time the offending food is ingested.
What is Food Intolerance?
- Food intolerance, also known as delayed or masked onset type, generally occurs gradually and does not involve an immune system reaction.
- It is due to immunological mediated responses but it does not involve the IgE antibody. Instead studies have shown it to be linked to the presence of an antibody called IgG.
What are the signs?
- The reaction occurs from two to 72 hours after ingesting the offending food.
- It’s triggered by food eaten frequently and often in larger quantities.
- It frequently involves four, five or even more types of food. As such, one is usually unable to establish a relationship between the offending food and reaction. Therefore, it is often thought to be a food allergy.
- Although the symptoms tend to be low grade, the problem is that they are often chronic, recurrent and associated with inflamation in multiple organ systems.
Causes of Food Intolerance
Dr Chong Yong Yeow, Specialist in Internal Medicine and Rhumatology, Raffles Internal Medicine Centre, shares five causes of food intolerance.
- Food poisoning – when spoiled food is consumed, the bacteria can cause severe digestive symptoms.
- Celiac disease – celiac disease has some features of a true food allergy because it does involve the immune system. However, symptoms are mostly gastrointestinal, and people with celiac disease are not at risk of anaphylaxis. This chronic digestive condition is triggered by eating gluten, a protein found in wheat and other grains.
- Absence of an enzyme required to fully digest a food – a common example is lactose intolerance.
- Sensitive to food additives – for example, sulfites used to preserve dried fruit (or wine) can trigger asthma attacks in people who are sensitive to it.
- Irritable bowel syndrome – this chronic condition can cause a myriad of symptoms such as constipation, diarrhoea and cramps.
Is There a Remedy After All?
“Mainstay of treatment of IgE-mediated food allergy is still avoidance. You are advised to read food labels carefully and have an action plan, such as being equipped with an emergency epinephrine shot (e.g. EpiPen and Twinject) for emergency self-treatment, in the event of accidental ingestion,” advised Dr Chong.
For children, Dr Chu Hui Ping, Specialist in Paediatrics, Raffles Children’s Centre, advised concerned parents to keep a food diary on the foods that their children eat. Use it to also keep track of the symptoms that they may be have due to food allergy, and how soon after the ingestion of food does the symptoms occur. More notably, always seek medical advice from a doctor.
