One of the most compelling theories about MS is that of a kind of slow poisoning. The human body contains a sophisticated filtering system within the walls of blood vessels called the endothelium which keeps away separate harmful substances that can damage nerves. In the brain this filtering system is known as the blood brain barrier. In persons suffering from MS something happens to allow harmful neurotoxins to penetrate the blood brain barrier. Penetration of the blood brain barrier is often the earliest detectable abnormality in MS.

A number of things can cause the barrier to be breached, including stress, fever, emotional upset, heat, injury and eating too much fat. These things allow poisonous chemicals in the blood to leak into the blood stream where they can cause severe damage.

MS sufferers may be victims of a kind of toxic overload from man made poisons. A convincing example of this would be the "outbreak" of MS in Key West, Florida between 1983-85. During that time 30 to 40 people developed MS. This was eventually traced to the dumping of toxic debris containing high levels of mercury and lead nearby (Am J Forensic Med & Pathology, 1986; 7(1): 3-8).

Mercury is one of the most potent neurotoxins known to man. Over the years there have been other convincing pieces of research into the mercury MS connection (Br Dental J, 1993; 175(10): 355-62). Most recently, a Swedish study showed that the normal mercury level in the spinal fluid contained 0.4 micrograms per litre; in MS victims studies that level rose to an average of 3.0 micrograms per litre more than seven times the normal level.

It concluded that dental fillings were the most likely source of this form of poisoning and confirmed that sufferers often responded well when amalgam fillings were replaced (Swed J Biol Med, January 1989). This has been reflected in other journals as well (Psych Reports, 1992; 70(3, pt 2): 1139-51).

Mercury from the dental amalgams in our mouths is one of the most common sources of direct poisoning. In his book, Dr Hal Huggins, a dentist and vociferous critic of mercury fillings (Avery, 1993) quotes a summary by Douglas Swartzendruber, PhD, of all the scientific literature relating MS not only to mercury in general, but specifically from dental fillings.

Dr Patrick Kingsley, the UK's leading expert on MS, said that of his nearly 4,000 patients seen with the problem, only five didn't suffer from mercury poison.

The second most common problem, is Dr Kingsley's view, is food intolerance. Although gluten is most often implicated, he finds that allergies are individual and there is rarely a single culprit that he can point to. A systemic candida infection also is often behind MS.

Next down the line of causes, he finds, are nutritional deficiencies, chiefly B12 and magnesium, but also B6, folic acid amd zinc. Pesticides, moulds and many other environmental toxins play their part.

Kingsley sums the problem up this way. "Multiple sclerosis is a name we've given to a collection of symptoms symptoms which could be caused by anything. The problem is that medicine likes to assume that everybody with the same symptoms is suffering from the same disease, which is caused by the same cause and therefore will respond to the same treatment. So for instance, if something like MS responds well to diet, medicine will immediately assume that there is one diet which will cure all."