Food Allergy Vs Food Intolerance
Food is our fuel, it’s our medicine and it should be enjoyed to our very soul. This is not always the case for some people though. For people with food allergies or intolerances, food can be a cause of anxiety and can make them feel very unwell. It can also potentially be quite dangerous. It’s important however to distinguish between a food allergy and a food intolerance because they not only affect the body very differently but they also must be treated differently as well.
FOOD INTOLERANCE
Food intolerance does not involve the immune system. It is caused by two mechanisms: the inability to digest and absorb some food molecules, which pass undigested into the bowel and cause IBS symptoms. The other is a food chemical sensitivity, which is caused by natural or added food chemicals that irritate the nerve endings of some body parts.
1. FODMAP intolerance
FODMAP is an acronym for a group of fermentable, short-chain carbohydrates found in our everyday diet that some people cannot digest and absorb properly. When these undigested molecules travel down the intestines they either cause an osmotic rush of fluids into the bowel or they pass through to the large bowel where they are fermented by the bacteria in the gut. It’s not harmful to eat high FODMAP foods but if you have an extreme reaction to them it can be incredibly uncomfortable and sometimes painful for a short time until the food and gas has passed through your system. The reactions caused are what we know as typical IBS symptoms:
Severe bloating and gut distension – often getting progressively worse over the day
Excessive wind and flatulence
Gut pain
Gurgling stomach
Diarrhoea or loose stools, often with urgency
Constipation
It’s not uncommon for FODMAP intolerance to come on in adulthood. The exact reason is unknown but there seems to be a correlation between sensitivities from altered gut flora such as an overgrowth of some bacteria or the presence of gut bacterial or parasitic pathogens. Or potentially even from increased stress and hormonal changes.
How to treat FODMAP intolerance?
In order to uncover a food intolerance, you need to start by eliminating all known problem foods for 4-6 weeks until you’re virtually symptom-free. Then, one-by-one you can trial several foods from each food category to assess whether there was a reaction. It’s always best to do this elimination diet with the support of a Dietitian so it can be individualised to you and so it’s followed comprehensively whilst still being able to optimise your nutrition.
The following are some foods that are high FODMAP:
Fructose – asparagus, artichoke, apples, pears, watermelon, honey
Lactose – milk, yoghurt, ice cream, custard, condensed milk, fresh cheeses
Polyols – stone fruit, mushrooms, sweeteners (sorbitol, mannitol, xylitol, isomalt)
Galacto-oligosaccharides (GOS) – legumes and lentils
Fructans – garlic, leek, onion, shallots, inulin and the grains wheat, rye and barley as the main ingredient in a food.
Most high FODMAP foods are really good for us and play a role as prebiotics or food for the bacteria in our bowel, which is a normal process. Prebiotics are essential for gut health so it’s important not to eliminate all these foods long-term. It’s unlikely you’ll react to every food category so finding the problem food category is the key so you can return ‘OK’ foods back into your diet as soon as possible. It is also possible to build your tolerance to some foods such as legumes and lentils, particularly for vegans and vegetarians. Start with a very small amount of the food and slowly build up the amount over time. You may also be able to get away with a certain amount of some problem foods. For example, if you have an intolerance to lactose, you may be able to enjoy half a glass of milk but any more than that may cause a reaction. To figure this out takes a little trial and error.
2. Food chemical sensitivity
A food chemical sensitivity is caused by the irritation of nerve endings from the build up of certain natural as well as added food chemicals in your system. These are known as salicylates, amines and glutamates. Some people are more sensitive than others and this is believed to be genetic but you can develop a sensitivity at any age after a viral infection, a food or drug reaction or an abrupt change to your diet.
The most common symptoms of a food chemical sensitivity are:
Hives
Swelling around the face and eyes
Headaches and sinus problems
Mouth ulcers and tingling lips and tongue
Nausea, stomach pains and erratic bowels
Aches and pains
Tired and moody
How to treat a food chemical intolerance?
We all have different tolerance levels to food chemicals but for someone with a low threshold to them, they build up cumulatively in their system until they reach a threshold and symptoms begin. For this reason, it can be really difficult to work out which foods are a problem because any one food can tip you over the edge.
Once again, you will need the support of a Dietitian to follow a strict low food chemical sensitivity diet for 3-4 weeks to see if symptoms disappear. Then you can do a food challenge to identify the problem foods. The time spent eliminating problem foods can reduce overall chemical levels in the body so that long term you should be able to enjoy small amounts of those foods without ever reaching your threshold.
Salicylate foods: many fruits, vegetables, nuts, tea, coffee, herbs & spices
Amine foods: chocolate, aged or smoked meats and fish, some sauces, stocks, soups, nuts, seeds & vinegar
Glutamate foods: MSG both natural and added, cheeses, some fruit and vegetables and meat extracts like stocks and gravies.
3. Non-coeliac gluten sensitivity
This phenomenon occurs when an individual does not have coealic disease but still experiences the same symptoms after eating gluten, such as:
Bloating
Flatulence
Abdominal pain
Diarrhoea
Foggy head and lack of concentration
Lethargy and low energy
General aches & pains
How to treat non-coeliac gluten intolerance?
It’s essential that if you suspect you have a problem digesting gluten, that you first eliminate coeliac disease as a cause. This involves a blood test and if that returns positive then follow up with a biopsy of the small bowel to confirm this. You will need to continue eating gluten throughout this process so that any reaction to it can be detected.
If however the results return negative, removing gluten from your diet is the best way to determine then if you have non-coeliac gluten intolerance because your symptoms should disappear. Once again, your tolerance level may vary so that you can get away with having a slice of good quality sourdough but you feel terrible after a bowl of pasta. This takes a little trial and error. Remember as well that if symptoms still haven’t fully disappeared, to consider the low FODMAP diet, which is a far more comprehensive elimination diet that might uncover some other problem foods.
FOOD ALLERGY
A food allergy involves the body’s immune system, which sees some foods as foreign and creates antibodies in its defence. Food allergies usually begin in childhood but can start in adulthood, come on almost immediately when you’re exposed and involve the respiratory system and the skin. However the gut can be affected too causing stomach pain, nausea and vomiting, constipation, diarrhoea and reflux. The most common food allergens for adults are shellfish, fish, peanuts and tree nuts.
How to treat a food allergy?
Your GP can test you for these allergens with a simple blood or skin prick test and if any foods return as something you’re allergic to, you can eliminate these foods for good to avoid any reactions. There is also an allergy elimination diet that you can follow with a Dietitian’s guidance that takes around 2-4 weeks to complete. This requires removing all allergenic foods and then challenging each one to detect a reaction.
Coealic disease
Coeliac disease needs a special section to itself because it is not technically a food allergy but it does involve the immune system. Coeliac disease is an auto-immune disease, which means the body mistakenly identifies gluten as a foreign object and begins to attack the lining of the small intestine, causing inflammation. This also flattens the little villi that absorb the nutrients into our body so many people diagnosed with coeliac disease often have nutrient deficiencies such as calcium or iron deficiency as well.
The main symptoms of coeliac disease are hard, sore upper abdomen, diarrhoea or constipation, fatigue and ‘the gluten fog’ which is a foggy head and difficulty concentrating.
As mentioned above, the only way to diagnose coeliac disease is through a blood test that tests whether you have the gene susceptible for coeliac disease and if you have raised antibodies in your blood meaning there is an immune reaction occurring. If these tests are positive then the ‘gold standard’ test is then to follow up with an endoscopy and biopsy of the small bowel to determine whether there is damage to the intestinal wall.
References:
http://shepherdworks.com.au/disease-information/low-fodmap-diet/
http://www.slhd.nsw.gov.au/rpa/allergy/resources/foodintol/ffintro.html
http://www.allergy.org.au/patients/food-other-adverse-reactions/food-intolerance