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Food Intolerance - Dispelling the Myths

Wednesday, 17 February 2010

Valerie Kelly - Dietitian

Dr. Conor O'Brien - Gasteroenterologist - Beaumont Hospital

Emma Clarke Conway - Spokesperson for the Celiac Society

Valerie Kelly:- Dietitian:-

What is a food intolerance?

A food intolerance really just means an unpleasant reaction to a food. What is really important, however is to highlight the difference between a food 'allergy' and a food 'intolerance'.

What is some of the myths/misconceptions of food intolerances?

People need to remember is that there is an industry surrounding food allergy and intolerance that is worth billions of dollars a year. There are many so-called allergy clinics out there charging large sums of money to test people for food allergies.

The tests they are using are not scientifically reliable and the people doing them are not qualified health professionals. As a result people are unnecessarily going on very restricted diets that can be dangerous to their health. More often then not, these clinics are also encouraging people to buy expensive nutritional supplements to supplement their diets after they have cut out the foods they are supposedly allergic to.

If you suspect that your child has an allergy, they should go to their GP or hospital and be properly assessed by a qualified doctor.

Food Intolerance:

Nowadays people use the term 'food intolerance' to describe a whole range of unpleasant reactions to food. It has to be said that food intolerance has become something of a trend with women's magazines and websites convincing people that any level of pain or discomfort in your bowels is down to a food intolerance.

The true incidence of food intolerance is harder to estimate as there is no real method of diagnosing a food intolerance. Symptoms of food intolerance can be anything from nausea, bloating and diarrhoea to headache.

An example of a food intolerance would be lactose intolerance which is rare in adults but in babies can cause diarrhoea and is a result of not having enough of the enzyme in the gut needed to digest milk. The lactose intolerance disappears in a few weeks in most cases.

Most food intolerances are dose related meaning you might be able to tolerate a little bit of the food but any more than that will make you feel uncomfortable.

Intolerances don't involve the immune system and therefore don't result in symptoms such as itchiness, hives, rash and swelling. This is why food intolerances are not life threatening and food allergies can be.

What if you feel bloated/uncomfortable/tired regularly after certain foods?

Feeling bloated or tired after eating does not mean that you have a food allergy or intolerance. Eating a lot of certain things can make you feel uncomfortable. A lot of something like lentils could make you feel bloated and full of wind but that does not mean you are intolerant to them.

Fibre:- Irish people aren't eating enough fruit and vegetables and not enough fibre in general. Fibre is very important for helping to move food along the gut and if you aren't eating enough fibre it could cause your bowel to become sluggish and that may make you feel bloated.

Exercise:- helps move food along your gut and if you aren't getting enough exercise you may suffer from symptoms such as constipation.

It's also entirely possible that certain foods don't agree with certain people for any number of reasons. This may mean they would prefer to avoid eating that food but it doesn't mean they have to avoid all similar foods also

If there is a bad reaction to certain foods, it is possible that you could have a food allergy. This would mean that your symptoms would be noticeable and constant.

Food Allergy:

The actual incidence of food allergy in the Irish population is quite low, it's about 1-2%.

Food allergies are more common in childhood, however (about 6%) as children tend to grow out of certain food allergies, particularly milk and egg. A child with a nut or a fish allergy, however is less likely to grow out of it.

While food allergies can be diagnosed at any age, the majority of food allergies will be diagnosed before the age of three. An exception to this would be fish or shellfish allergy which tends to be diagnosed in teenagers or young adults.

With a food allergy, the immune system causes the reaction. The body recognises the food as an 'invader' as such, and releases antibodies and chemicals that make you feel unwell and cause symptoms such as itchy skin, rash, hives, swelling of the lips and tongue, streaming nose, wheezing. It can also cause symptoms such as diarrhoea and vomiting.

In severe cases, you may not even need to eat the food to get a reaction. Kissing someone goodbye who has eaten the food can cause a reaction in someone who is sensitive enough.

There are certain tests that can be done (see below) to help confirm the diagnosis of a food allergy.

What are the most common intolerances and allergies?

Common food allergies in Ireland and the UK are:

. Cow's milk
. Egg
. Soya
. Wheat
. Peanut
. Tree nuts
. Fish
. Shellfish

Food allergy v Food Intolerance

Food Allergy Food Intolerance

Involves the immune system Doesn't involve the immune system

Reproducible reaction Reproducible reaction

Will react to the tiniest bit of May be able to tolerate bits of

bit of the allergenic food the allergenic food

Can be life threatening Generally not life threatening

Relatively rare Can be more common

What is a dairy intolerance?

Cow's milk intolerance is really not a medically recognised condition. Feeling unwell or uncomfortable after drinking cow's milk or eating products containing cow's milk.

This is different to an allergy to cow's milk which would mean that after eating products containing cow's milk the person may have symptoms such as vomiting and diarrhoea, rash, hives, swollen lips.

How is it diagnosed?

There is no way of diagnosing an intolerance but there are ways of diagnosing allergies (as mentioned in the previous questions). However, many so-called allergy clinics around the country will take a sample of your blood and diagnose you with an intolerance to milk but these are not scientifically sound methods they are using.

Is this the same as lactose intolerance?

Lactose intolerance is however, another thing altogether. It is an intolerance to lactose, the sugar in milk and it causes diarrhoea. It is really only seen in infants (Irish infants also) and people of Afro Caribbean origin.

If you feel uncomfortable after dairy products, should you exclude them from your diet?

People need to be very careful cutting whole food groups such as dairy products from their diets. Calcium is very important for bone health and if a person is going to avoid dairy products they need to get their calcium from elsewhere - for example something like soya milk. One in 5 men and 1 in 2 women over 50 will develop a fracture due to Osteoporosis in their lifetime. Avoiding milk has even greater implications for children. Children should not be put on a milk free diet without confirmation of a genuine allergy from a medical doctor and not without the advice of a qualified dietitian. I have seen many children who have ended up very malnourished after being taken off cow's milk without correct advice and support.

Dairy (Lactose) intolerance Symptoms:-

. Abdominal pain
. Bloating
. Flatulence
. Diarrhoea
. Vomiting

It is not an allergy but arises as a result of a deficiency of the enzyme lactase in the intestine which breaks down lactose. The symptoms described can range from mild to severe.

If left untreated, a patient's symptoms will often continue. However tolerance may occur and the symptoms may reduce over time. It is important to monitor for specific nutrient deficiencies such as vitamin d and calcium

Irritable Bowel Syndrome:

What is IBS?

IBS is a chronic relapsing gastrointestinal problem, characterised by abdominal pain, bloating and changes in bowel habit.


. Abdominal pain
. Inconsistent Bowel Frequency (resulting in either diarrheoa, constipation or both),
. Change in stool consistency,
. Abdominal bloating
. Urgency and the passage of mucus.
. Gastroenteritis
. Risk Factors
. Fibromyalgia
. Chronic Fatigue Syndrome
. Chronic Pelvic Pain
. Anxiety/Mood disorders

Is it a Food intolerance?

No, but symptoms in IBS often occur after food and therefore many patients attribute their symptoms to particular food ingestion or a food 'intolerance'. There is very little evidence to suggest that IBS patients have an allergic or immune -based reaction to certain foods. Some patients do definitely exhibit some form of food intolerance but the mechanisms of this are not understood.

What do you do if a patient feels that their symptoms worsen after certain foods?

The best method of identifying the offending food is to exclude this from the diet and firstly see if the symptoms resolve and if so, do they re-appear on re-introduction of the food. This should ideally be performed under the guidance of a dietician as dietary exclusion can become problematic if the diet becomes so restricted as to become nutritionally inadequate.

Diet assessment and adjustment is important in the management of patients with IBS. People with IBS often find that following healthy eating advice may exacerbate their symptoms.

It may be helpful to limit the intake of foods containing a lot of insoluble fibre (wholemeal breads, high-bran cereals, wholegrain brown rice). People with flatulence and bloating may benefit from increasing their intake of soluble fibre as found in oats and linseeds. Patients are also advised to reduce their intake of 'resistant starch' found in processed and re-cooked foods such as potatoes.

If IBS is left untreated, patients' symptoms may continue but there is no association between IBS and the development of any serious disease.

How does an IBS sufferer change their diet?

Irritable bowel syndrome can cause all sorts of symptoms ranging from constipation and wind to diarrhoea and nausea and can be very distressing for the sufferer. People with IBS should really be seen by a dietitian to get advice specific to them but the following general advice applies:

. Regular meals and avoid long gaps without eating
. Restrict tea and coffee to three cups per day
. Reduce intake of alcohol and fizzy drinks
. Drink at least 8 cups of fluid per day
. Avoid artificial sweeteners
. Reduce intake of insoluble fibre

A Word on Fibre for People with IBS:

Someone with IBS may need to took at how much fibre is in their diet. In the past it was recommended that people with IBS increase the fibre in their diet but many patients find this worsens their symptoms.

There are two types of fibre, soluble and insoluble.

Soluble fibre is found in oats, nuts and seeds and some fruit and vegetables.

Insoluble fibre is found in wheat bran, corn, edible skins and certain vegetables.

Generally IBS sufferers find soluble fibre easier on their gut.

The message really is: fibre is important for gut health and people with IBS should be including fibre in their diet but too much fibre, especially insoluble fibre may make their symptoms worse.


Probiotics are 'friendly bacteria' found in certain food supplements and yoghurts. Reseach done on probiotics and IBS have found that they may help alleviate abdominal pain and discomfort. They won't do any harm anyway and the yoghurts are a source of calcium and protein.

IBS and lactose:

Lactose is the sugar that is naturally present in milk (cow, human, sheep, goat). Some IBS sufferers feel it can make their symproms worse.

Small amounts of lactose spread out over the day can be tolerated by most of those who feel it makes their symptoms worse in larger amounts.

Again, if someone is avoiding dairy products, they need to replace it with something else to ensure they do not lose out on calcium and other vitamins and minerals.

Coeliac Disease:

Coeliac disease is a condition where gluten, a component of wheat, barley and rye, produces an inflammatory or allergic reaction in the small intestine.

The small intestine is responsible for the absorption of food and nutrients and therefore inflammation here can result in malabsorption of essential nutrients.

In the mildest form of coeliac disease, there may be no symptoms at all. However at this stage simple blood tests may demonstrate that you are not absorbing nutrients properly.

How do I know if I'm Coeliac?

There is a wide variety of symptoms seen in coeliac disease and when these symptoms are severe, they would certainly impact on your quality of life.

Other Symptoms:

. Diarrhoea
. Abdominal pain
. Weight loss
. Excessive gas production.
. Conditions often seen in association with coeliac disease
. Osteoporosis
. Diabetes
. Anaemia
. Dermatitis herpetiformis (skin rash)

When can it be diagnosed?

Coeliac disease can be diagnosed at any age and becomes increasingly prevalent with age. Up to 15% of coeliac patients are diagnosed after the age of 65. The prevalence of the condition in Ireland is approximately 1 in 100.

What causes it?

The exact cause of coeliac disease is unknown.

Risk Factors:

. Family History
. Bowel Infections
. Bowel Surgery

If left undiagnosed?

Coeliac disease is associated with a slight increased mortality compared with the general population. There is a small increased risk of cancer of the lymph glands and of the gastrointestinal tract and this risk is increased in the untreated coeliac. The other risks of not treating coeliac disease relate to the complications of malabsorption including, osteoporosis, anaemia, vitamin deficiencies and weight loss.