Death Panels is a word really conservative Americans (and Fox news) like to throw around to scare people away from considering universal health care.
For the most part I think it is a load of cr@p. Most evidence does not show that universal health care results in lower life-expectancy - rather, just the opposite.
Take a look at life expectancy in both Canada and the UK (both countries with "Death Panels" according to Fox). The life expectancy is higher.
I do think some of our treatment of the elderly could seriously be improved. The elderly are not disposable because they are elderly. Vit. B 12 comes to mind, and I doubt you are wrong about the Vit. D. I do think this is an age group that is heavily susceptible to "advice by authorities" and that is something we need to watch out for. None of this is related to Obamacare or private insurance.