@PyreneanAubrie I'm a bit reluctant to contradict you but some of the points you make are incorrect.
Vit D and calcium do not prevent or treat osteoporosis, unfortunately. There is now also a lot of research coming out to show that calcium supplements can be dangerous and cause arterial damage. This is because we can't absorb calcium in large amounts from a tablet and it's laid down in the arteries.
Blood tests won't diagnose osteoporosis. You can have normal Vit D and calcium levels but they aren't going to be of any use. Unless you've had a DEXA scan you won't know your bones are okay.
I've had DEXA scans for almost 20 years to prevent osteopenia becoming osteoporosis.)
The only people who should take these are the very elderly who don't eat a proper diet and the same goes for large doses of Vit D.
Prof Tim Spector who was an osteoporosis specialist before becoming an epidemiologist has written about this recently and quoted research.
https://uk.news.yahoo.com/nutrition-expert-professor-tim-spector-131901520.html#:~:text=%E2%80%9CSo%20unless%20you%20have%20some,sources%20of%20calcium%20exist%2C%20particularly
“I used to advise my patients to drink milk and dairy, and the research has changed over the years. Now very clear that having large amounts of calcium-rich dairy does not protect your bones against osteoporosis. It doesn’t have any major benefits for the body. And there’s increasing evidence that extra calcium, particularly in the form of calcium supplements, increases your risk of heart disease.
“So unless you have some really important medical disorder or some in inability to absorb calcium naturally you don’t need supplements.” Prof Spector said that taking calcium supplements could in fact be harmful to health and explained: “Most people don’t realise that many other sources of calcium exist, particularly things like leafy greens or nuts and seeds. And we’ve evolved fantastic systems to absorb all the calcium we need.”