Les - thanks, those are much better sources. The excellent thing about the scientific approach is that we can change our views as better data becomes available and as we expand our experience and knowledge. Shame on all those academics going back on old data and updating and rechecking in light of new methods or understanding, right?
The other thing to be careful about is comments like "they're well into their 80s and very healthy" - which is a paraphrase, of course. There are people with all sorts of diets who live well into their 80s. "Eat food. Mostly plants. Not too much.". Individuals clearly react differently to different diets. You can take two people, the same age, sex, weight, height, basic health profile and background, same sugar levels and feed them a packet of jelly beans. Once of them will spike their sugar levels and the other will have almost no reaction. The current investigations are into customised diets based on a wide range of input and baseline factors and data that can provide general direction to individuals about what would suit them the best. That's really exciting stuff - understanding sufficient to deliver targeted results. Again, shame on those academics!
Regarding calcium - I remember 20 odd years ago when I snapped my tibia and fibula in half and had my leg put back together, that the doctor talked to me about calcium and so on to support regrowth. He asked me about my diet, which is pretty common - more meat than is probably ideal, but lots of vegetables and a fish, meat, grains, dairy, etc. In other words, a wide variety of things. He said I wouldn't have any problems and a supplement wouldn't be of any use because I should be getting all the calcium I need already. Only in the last few years have we finally seen commentary about the vast waste and con that the dietary supplement industry largely is. Unless you're shown to be deficient in something and can't get it any other way, supplements are of little to no value.