The average human adult body contains 2 to 5 mg of Vitamin B12, of which about half is stored in the liver. Other than resulting from insufficient stomach acid for which acid-lowering drugs, or H. Pylori infection may be responsible, cobalt or Vitamin B12 deficiency can develop from malfunctioning or surgical removal of parts of the stomach or small intestines, from celiac disease, parasites, or other malabsorption disorders. Cobalt Deficiency is not a major problem though as long as one has adequate amounts of Vitamin B12... Full Text

Manganese may help with some symptoms of Parkinson's disease such as muscle rigidity and twitching...
Research shows that phytosterols such as beta-sitosterol may help normalize the function of natural killer cells and T-helper lymphocytes...
Iron deficiency may be suspect with some forms of ADHD. 84% of children with ADHD were found to have abnormally low levels of ferritin...
A high intake of B Vitamins can trigger heart palpitations, HBP, major complications in patients with congestive heart disease...