Some symptoms of a selenium deficiency:
Multiple Sclerosis (MS)
Muscular Dystrophy (MD)
Cirrhisis of the liver
Sickle cell anemia
Sudden Infant Death Syndrome (SIDS)
Some symptoms of excess (toxicity); hinders performance of certain enzymes, can cause hair loss, fever, dermatitis, paralysis, muscular problems, heart problems, increased tooth decay, skin inflammation, nausea, fatigue, liver and kidney impairment.
Natural sources: organ meats (liver, kidney), seafood, whole grains, and many natural foods.