Originally Posted by Sailor
The way my doctor explained it - when it's an allergy, your body creates antibodies to fight the "food" you've put in. Usually, the reaction is against the protein. But, not always. Whereas the food intolerance is often a digestive system response - whether from lack of enzymes or other issue. But, obviously, not always. lol ... I guess it's never good to generalize.
From all that I've read, the jury is still out on what exactly a food intolerance is and how it effects our body. Conventional medicine and science tend to shun the idea that the presence of IgG antibodies to food means anything at all health-wise. This is partly because most people have low level antibodies to many foods and partly because not many scientific studies have shown good evidence that IgG antibodies to foods = ill health from eating those foods.
There have been a few studies showing that removing foods identified in IgG tests help irritable bowel syndrome and at least one study that queried 4,000 patients who used the results of food intolerance testing about health benefits. This is relatively limited evidence overall, though. If IgG antibodies do play a part in ill-health, then exactly how, is still undetermined. If you read the literature from many of the companies who offer these sorts of tests, they claim a large number of health issues (way beyond 'digestive') can be caused by food intolerance.
An unarguable tenet, however, is a positive health effect from food elimination. If you feel better without it, leave it out. We saw a remarkable improvement in our DS when we cut out wheat and this was before we got the results of his IgG test, which indeed, confirmed wheat, gluten and cow's milk sensitivities. I understood the dubious nature of the test (according to science and many allergists anyway) before ordering it but was more convinced of its accuracy when the foods we suspected causing problems in DS (from food journal/elimination) were the same foods that came back positive on the test (with the exception of soy and potato.) My son's bottom went from a constant diaper rash to almost healed in just a few days after eliminating wheat/gluten.
Overall, I think the scientific method is hard to apply when it comes to foods, diet and nutrition. The immune system is complicated and there are parts we still don't understand -- so, science still has a lot to learn about both.
Overall, though, if your doc drew blood, he is likely looking for an IgE antibody. This will tell you if you have a true allergy
to a substance. If you do, then you'll have to avoid it completely to prevent possibly escalating and/or serious reactions.