<unk>  or<unk>  sensitivity is a negative reaction to a<unk>  that may or may not be related to the immune system or to<unk>  poisoning. It can be caused by the absence of specific chemicals or enzymes needed to digest a<unk>  substance, or by the body's responses and reactions to certain<unk>  constituents (chemicals) both natural or artificial.  Symptoms of<unk>  vary greatly, and can be mistaken for the symptoms of an allergy. While true allergies are associated with fast-acting immunoglobulin IgE responses, it can be difficult to determine the offending<unk>  causing an<unk>  because if the immune system is involved, the response is likely to be IgG mediated and takes place over a prolonged period of time. Thus the causative agent and the response are separated in time, and may not be obviously related.  A deficiency in digestive enzymes can also cause some types of<unk> s. Lactose<unk>  is a result of the body not producing enough lactase used to break down the lactose in milk. Gluten<unk>  results in damage to villi in the small intestine, which makes it difficult for the body to absorb water and nutrients from<unk> s. Another type of<unk>  is an<unk>  to<unk>  chemicals such as salicylates or salicylate sensitivity. Salicylates are chemicals that can occur naturally in many<unk> s. Salicylate sensitivity causes many symptoms the most common of which are: hives, stomach pain, headaches, mouth ulcers, and it has even been linked to ADD and ADHD.<unk>  can exist as a separate condition or contribute to the symptoms of complex syndromes such as Chronic Fatigue Syndrome CFS/CFIDS, Myalgic Encephalomyelitis  ME, Post-Viral Fatigue Syndrome PVFS and may involve causes such as Leaky Gut Syndrome. For these reasons diagnosis is best carried out by experienced practitioners.  Symptoms of a<unk>  include gas, intermittent diarrhea, constipation, irritable bowel syndrome, skin rashes, migraine headaches, and an unproductive cough.
Food intolerance
Dysphagia
Steatorrhea
Chronic diarrhea
Constipation  
Constipation
Odynophagia
Dyspepsia