I have no idea what the numbers were, I took it in as a system idea: more time in sunlight, more UVB, more Vitamin D. Then UVA breaks it down slowly, so more builds up in the skin, more is being broken down, acting as a control-feedback brake on the increase.
> "unless they supplement"
I have seen plenty of claims that low levels of Vitamin D correlate with many diseases and overall mortality, but that supplementing Vitamin D hasn't been proven to help. Is there any consensus on that?
> "as long as you're accounting for the calcium".
Vitamin D helps bodies absorb calcium but has concerns about high blood levels of calcium. Taking Vitamin K2 as well helps redirect that calcium to the bones instead of the artery walls, apparently. But high levels of Vitamin A could also be causing loss of bone calcium into the blood:
"""in the industrialized world excess of vitamin A has been suggested to be a risk factor for secondary osteoporosis and enhanced susceptibility to fractures. Preclinical studies unequivocally have shown that increased amounts of vitamin A cause decreased cortical bone mass and weaker bones due to enhanced periosteal bone resorption. Initial clinical studies demonstrated a negative association between intake of vitamin A, as well as serum levels of vitamin A, and bone mass and fracture susceptibility. In some studies, these observations have been confirmed, but in other studies no such associations have been observed. One meta-analysis found that both low and high serum levels of vitamin A were associated with increased relative risk of hip fractures.""" - https://pmc.ncbi.nlm.nih.gov/articles/PMC11070503/
which could be a confounding factor with Vitamin A and its precursors in so many animal and plant foods and fortified into more, and in daily multivitamin supplements, skin creams, moisturisers and such.