Also to add to the above, the article below is a case study of a patient who suffered what appeared to be a psychiatric breakdown but was found to be caused by B12 and iron deficiency. http://www.ncbi.nlm.nih.gov/pubmed/15029091 The interesting thing is that doctors tell us we can get all of our nutrients from a balanced diet but what constitutes a balanced diet? And other factors have to be taken into consideration. People can have parasitical infections, Croehns disease, IBS, low stomach acidity which will all contribute to decreased nutrient absorption from their diets (particuarly a problem with B12). Throw in genetic polymorphisms and allergies etc and it gets even more tricky to understand. Then there is also the possibility that much of the food we eat is low in nutrients because of depleted soils, high productivity/fast turnover of crops & livestock so their is less time for essential nutrients to be absorbed etc…. Also modern humans are now exposed to 10,000s of industrial chemicals that we have no idea of how they interact biologically. Don’t expect the FDA or EPA to protect you. How long did it take for them to ban asbestos, lead additives in fuel and paint, DDT, dioxins, mercury fillings etc…. In the meantime our plastic food storage containers contain BPA, aerosol cans have aluminium, our crops are exposed to pesticides, we insist on building residential homes in areas exposed to diesel fumes, restaurants add MSG to their food, we cook with non-stick pans etc. Now we also have low fat foods that are packed full of sugar or artificial sweeteners instead….aspartame which will breakdown in the blood to methanol and formaldehyde….. Do we really know what we are doing to our longterm health? Are these chemical exposures behind the rise in autoimmune disorders that we are now seeing?