that 'one person's meat is another's poison' recognises this important point. A substance
is poisonous or toxic for one person may not necessarily be harmful for another. For example,
gluten, a protein which occurs in wheat and to a lesser extent in oats, barley, and rye, is
just like any other protein by most people. However, for those people who suffer from coeliac
disease, eating foods containing gluten can damage the lining of their intestine. Another
affecting about 85 per cent of adults is the inability to fully digest lactose, the sugar which
naturally in milk. For these individuals the consumption of large quantities of milk can cause
diarrhoea. For some asthmatics, eating foods containing various forms of the food additive
sulphur dioxide will cause an allergy-like reaction which may even be life-threatening.
Some people will be more sensitive to certain substances than others, irrespective of whether the substance occurs naturally in food or is added. In practice, food additives are safe for the majority of the population but some individuals will inevitably be adversely affected. People who are sensitive to particular additives or foods must always check the ingredient list on foods before they consume them. The food additives most commonly associated with sensitivity include colours (most notably tartrazine), the preservatives benzoic acid and various forms of sulphur dioxide, and the flavour enhancer, monosodium glutamate (MSG). The numbering code used to identify specific food additives on food labels is listed in appendix 3.