Strong bones are the key to a longer life. Here is how to protect your bones. Calcium is the main component of bone mineral, but the other major component in bone is collagen. Raw-milk hard cheese and raw milk kefir are great sources of both https://www.telegraph.co.uk/health-fitness/conditions/bones-joints/strong-bones-key-to-longer-life-how-to-protect-them/ Vit D + Vit K2