This is a good explanation from The Net Doctor, of the differences between Allergy and Intolerance: (scroll down to end for information about private testing)
The Question was about further testing for Intolerances because of IBS symptoms, what follows is the Answer from The Net Doctor.
“I can understand your wish to find out exactly what has been causing your distressing irritable bowel symptoms, but I can also understand your GP’s advice with regard to food intolerance testing.
True food allergies usually cause life-threatening shock reactions such as severe breathlessness and tongue swelling.
Food intolerances, on the other hand, are notoriously difficult to test for.
A person’s tolerance to certain foods can vary from day to day, and it’s not clearly understood how some foods can cause such a variety of symptoms, but not a full-blown allergic reaction.
This means it is difficult to design a reliable test for the consistent detection of problem food.
There are a number of commercial ‘allergy testing’ kits available, but the effectiveness of many of them is questionable – results can differ even within the same person.
Doctors specialising in allergic reactions use blood tests to look for the level of immune reaction within the body, but these too often fail to pick up an intolerance.
The blood tests are designed to look at the body’s response to a foreign substance, rather than one that isn’t completely foreign, as is thought to be the case with a food causing intolerance symptoms.
As you have found, the most successful way of dealing with any intolerance is an exclusion diet.
This involves eliminating suspect foods from the diet and then gradually re-introducing them.
Problem foods soon make themselves known. I think the approach you have taken is therefore the most sensible. It would be a good idea to keep the suspect foods out of your diet for a bit longer. Then, try eating small amounts at a time and waiting a few days to observe any adverse effects before eating more.
Your GP may feel a referral to a dietician would be appropriate so you can ensure that your diet remains balanced.
I am delighted to hear that dietary manipulation has helped your IBS. It won’t work for everybody, but as long as it is done carefully and after taking suitable medical advice, it can be worth a go.”
Yours sincerely
The Medical Team, The Net Doctor
Basically an Allergy is a severe reaction to a food. An Intolerance is a reaction to a food that is not severe or life-threatening that may not always have the propensity to cause reactions perhaps depending on the strength or weakness of the Immune System at the time.
Just for the record there are two private tests which can be used to isolate Intolerances.
York Blood test. This will discern food intolerances if you are still eating the foods you are intolerant to. It can only test for what is ‘seen’ in your blood that day or a few days/weeks previously. So foods not consumed for several months, ie sea foods may not show in the blood.
Hair Analysis: This looks at your DNA and will only show the situation of your body from about 3 months in the past depending on how long it takes your hair to grow.
Going by the advice above I think it is well worth getting the blood test in the first instance before giving up any foods as I feel this is the most definitive.
Then if some symptoms are still evident and causing difficulties, try the elimination route as described above.
If there are still some uncertainties, you could then use the hair analysis test.
So lets assume you have taken the York Blood test and the result is that you have high intolerance to Wheat but low to milk. This may mean that you had not consumed much milk in the days leading up to the test. So eliminate ALL the foods that appear in the High, Medium or Low risk and see how you feel, eating only the foods in OK to Eat column. You can then experiment with eating foods in the low risk and see how you feel afterwards.
If after doing all you can, you still have symptoms, you could then try the Hair Analysis test, using this to mop up any information the Blood test may have missed.
York Blood test is considered the best and costs between £200 – £300.
I have not been recommended any particular Hair Analysis company but the costs are about £45.