<unk>  is described as the consequence of an insufficient dietary intake of the mineral<unk> .<unk>  was first proposed as an essential element for normal glucose metabolism in 1959, and was widely accepted as being such by the 1990s. Cases of deficiency were described in people who received all of their nutrition intravenously for long periods of time. The essentiality of<unk>  has been challenged. Whereas the authorities in the European Union do not recognize<unk>  as an essential nutrient, those in the United States do, and identify an adequate intake for adults as between 25 and 45 μg/day, depending on age and sex. Dietary supplements containing<unk>  are widely available in the United States, with claims for benefits for fasting plasma glucose, hemoglobin A1C and weight loss. Reviews report the changes as modest, and without scientific consensus that the changes have a clinically relevant impact.
Chromium deficiency
Fluorine deficiency
Boron deficiency 
Biotin deficiency
Metal toxicity
Lead poisoning
Fluoride toxicity
Selenium deficiency