Sometimes it can be difficult for a person to see a relationship between the foods eaten and symptoms experienced. An example of this is where someone eats food containing a mixture of glucose and fructose. Foods with a high glucose content can help to absorb fructose. And this can make it difficult for person to identify food triggers.
If someone is suffering from food intolerances, this means that the enzymes in your gut responsible for breaking down the food particles are either deficient, defective, or there may be an issue with the mechanism that transports molecules though the small intestine.
Undigested or malabsorbed sugars travel to the large intestine and is metabolised by normal colonic bacteria. gases such as hydrogen, methane, or carbon dioxide are produced. This may give rise to cramps, bloating and abdominal pain. This process may also have an osmotic effect by pulling water into the large intestine, causing diarrhoea.
A food intolerance may be diagnosed via an elimination diet, this is where certain foods are removed from the diet for a short period of time, typically 6 weeks. The foods in question are then reintroduced at a certain amount each day to gauge response. This should be done though a dietitian.
Breath tests can also be used to measure hydrogen and methane levels as a result of a sugar malabsorption. Lactose breath test, fructose breath test, sucrose breath tests are recommended.
Allergy Versus Intolerance
Food intolerances and food allergies are sometimes misunderstood and often the terminologies used interchangeably. However, there is a significant difference amongst the two.
Food allergies are the reaction from your immune system to a protein substance in the food, which is presumed to be a foreign harmful substance by the immune system.
This leads to the production of antibodies to fight off the foreign substance. The patient may experience symptoms, which range from mild rash to even anaphylactic reactions.
The igE antibodies produced by the immune system to an allergen can cause an immediate reaction. A non-igE reaction involves other components of the immune system and there may be a delayed response after exposure.
An example of a non-igE mediated food allergy would be cows milk. Symptoms are often delayed and can even take up to 72 hours to develop after exposure.
As well as the typical allergy symptoms, non-igE reactions may be associated with other GI symptoms and conditons such as reflux, vomiting, diarrohea, EoE, and coeliac disease. Non-igE allergies do not cause anaphalxis so rarely life-threatening.
Those with food intolerances may be able to consume a small amount of the food they are intolerant to without symptoms, for example some people with lactose intolerance may be able to tolerate a small amount of milk without suffering.
On the other hand, for those with allergies, even a tiny amount can be enough to cause an allergic reaction.
Testing – Facts and Myths
A skin prick test is often recommended to check for allergens. It is important that this is undertaken by an accredited allergy specialist who will use these results along with the clinical history to make a diagnosis.
For this test, different allergens are placed in separate areas of the forearm. The skin is scratched so that the allergens come in contact with immune cells. Itchiness, swelling or redness often indicate a positive reaction.
The elimination diet again is overseen by a Dietitian or immunologist or allergy specialist who removes certain foods from the patients diet.
It may be possible to try desensitization to a more severe allergy. It involves exposure to the allergy over time to essentially train your immune system to become more tolerant.
To diagnosis food intolerance, scientific evidence supports the use of breath test to measure carbohydrate malabsorption, or working with a dietitian.
There are several tests that are been offered commercially claiming to find out the cause of food intolerances.
One of these include tests that measure Immunoglobulin G (IgG) antibodies via skin prick testing kits.
The presence of IgG does not necessarily mean that it is a cause of intolerance. This is because this antibody has been found to be present in perfectly healthy people because the production of IgG is a normal reaction to food.
There is not much evidence that the food specific IgG tests are of any use in diagnosing any type of food intolerance, but quite worryingly, the results based on these tests have led people to avoiding some foods unnecessarily.
There are other commercially available tests such as the hair analysis test or saliva test that claim to be able to detect food allergies or intolerances from hair samples or saliva samples. Currently there is no scientific evidence to support this claim.
