Mrs Steve did clinical trials for ten years for anti-breast cancer drugs (Tamoxifen and Anastrozole), as she has the misfortune of belonging to two families with strong histories of the disease. As part of her trial she had several bone density scans which revealed that she was part-way between normal and osteoporosis (she's fine, by the way). For many years now she's taken vitamin D supplements which also contain calcium (the tablets are called Calcichew this end). B12 is present in many foods of animal origin. I myself am at slightly-increased risk of a deficiency because I have to take a proton pump inhibitor (lanzoprazole) to protect my gut from the NSAID I take for my bad back (life can be complicated!), and that can mess up B12 absorption to an extent. Hey ho. Just telling you what I know out of necessity. Advice elsewhere!