It has been my experience as a nurse for almost 30 years that this task is extremely difficult. The main thing to remember is that you want them to drink water preferably Alkaline water with Silica such as Fiji, Selzer, Vox, Smart Water, or Waiakea. These waters eliminate the bodies toxins of heavy metals which in turn will help the elderly person with their cognitive abilities. Coconut oil has also been effective in removing heavy metals in the body also, enhancing again cognitive ability. These two nutrients should be a mainstay in an elderly persons daily intake. Otherwise a healthy diet of fresh fruit, vegetables, and limited meat should be adequate for nutrition. Remember not to over feed the elderly, this may cause more harm than good.