So what is a food intolerance?

Food is our friend - or so we're told. We need to consume enough fuel to keep all our cellular activities going, all the amazing processes that we take for granted. But do we really give much thought to the quality of the fuel we give ourselves and what trouble might be brewing? It's like putting poor quality fuel into a high performance sports car - eventually the engine will just give out.
According to Allergy UK, 45% of the population suffer from some type of food intolerance * - that's an enormous percentage! So there's something or things in our standard diet that really shouldn't be there. And because we are all individual, it could be any number of things that affect each person differently. Some people may never find out what it is that makes them feel so tired and exhausted, or just take medication to 'relieve' their stomach pains or headaches. And is there anything wrong with that?  I believe there is, as masking the symptoms doesn't deal with the real cause, and continuing to bury the problem with chemicals that often just compound the issues is not a healthy or constructive way forward.
Allergy or Intolerance?
A food allergy is a potentially life threatening immune system response to a particular food stuff. For some reason the body's immune system has developed antibodies called IgE (immunoglobulin type E) which react to a specific food (peanuts is the most well known one). IgE molecules attach themselves to mast cells. When the antibody finds and combines with the allergen  it triggers the mast cell to release histamine and other chemicals to combat the perceived threat to the body, resulting in classic symptoms of allergy such as skin rashes, asthma, rhinitis or stomach upsets. A severe allergic reaction can result in immediate swelling of the face, throat and respiratory tract - these are known as type 1 allergic reactions and can be fatal. Often sufferers will carry epipens containing adrenaline to combat this type of severe reaction, or take anti-histamines.
A food intolerance, however, is more stealthy and chronic, and so harder to detect and diagnose. Symptoms of food intolerance can be so diverse that the symptoms could be caused by a huge number of different issues so it can take some time to find the root cause. This journey can be difficult and frustrating, especially if you find your GP to be rather conservative and unwilling to really deal with what they consider to be a minor issue that can be "cured" with pain killers or other medication.
According to Patrick Holford's great book "New Optimum Nutrition Bible" food intolerances are thought to involve IgG rather than IgE, a different marker that takes some time to react - anywhere between 2 hours and 3 days.  Often there are no symptoms. However, over time, IgG builds up and has a delayed, cumulative effect - so the more you eat of a particular substance that your body doesn't like, the more likely you are to develop a sensitivity.
Why me?
There are many explanations why food intolerances develop (another post) but why it happens to one person and not another is not so easy to explain. I'm sure it's the same reason why some people can smoke 20 a day all their lives and not develop lung disease, or how others can have massive amounts of salt in their diet and never develop high blood pressure or kidney disease - that's just the way it is.
Ironically, there is some research that suggests that the food you love is the one you develop the sensitivity to. Apparently, the proteins in the food are broken down into peptides before the single amino acids which are used at cellular level. Endorphins, the body's natural painkiller and feel good chemical, are also peptides and can be made from peptides taken from ingested food stuffs such as milk and wheat, giving you a short term feeling of well being when you eat that particular food stuff. So eating cream buns does make you feel good! Over indulgence over time can create problems. For me, I have always love cakes and creamy puddings much more than anything else on offer - the very same things that I can't eat now! It really is quite unfair!

** Allergy UK Report (2007)," Stolen Lives 3, The Food Allergy and Food Intolerance Report"