Increase Your Calcium Intake for Free.
Egg shells are rich in this necessary mineral, so why not harvest the calcium from a source that would otherwise be tossed in the garbage (or compost pile)?
Wash those shells, boil them for a few minutes, and add them, crushed, to diluted cider vinegar. Let stand overnight. The acid releases the calcium and the calcium neutralizes the sourness of the acid, so that you can add the resulting liquid. Add to your breakfast smoothie, or to any drink you have.