Your blood number moves; the colds and the mood scores do not
Monthly dosing pushed blood levels above 48 nanograms per millilitre while colds stayed identical. A year of daily dosing doubled them and changed none of nine outcomes.
What the study found
Blood levels rise on schedule, and the outcomes do not follow
Trial after trial moves the number and nothing else. Monthly dosing pushed blood 25-hydroxyvitamin D above 48 nanograms per millilitre while colds stayed identical. A year of daily dosing doubled it in low and depressed older adults, and changed none of nine outcomes.
The caveat · A pattern across unlike trials
Each of these trials recruited a different population and measured a different outcome, so what they share is a pattern rather than one replicated result. Three of the four used large intermittent doses, a schedule some analyses argue is the least effective. In one of them, the group whose levels reached the recommended target fell more often than the group whose levels did not.