Older adults do not necessarily need to avoid any specific standard vitamin entirely, but healthcare professionals strongly caution seniors against taking unmonitored, excessively high megadoses of fat-soluble vitamins (such as Vitamin A or Vitamin E) and certain individual minerals like iron unless specifically diagnosed with a deficiency. Excessive intake of unprescribed megadoses can lead to dangerous bodily accumulation, organ strain, and adverse drug interactions with common medications frequently prescribed to older demographics.