SarahChen_PharmD said:

Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the…

This matches mine closely enough to be worth saying so out loud.

SarahChen_PharmD said:

Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the…

There is a second half to this that has not been said yet. Worth answering the question that was asked rather than the one behind it. The narrow version usually has an answer; the broad version usually does not, and answering the broad one is how a thread stops being useful.

The figures, for anyone assembling their own picture. One habit that pays for itself: post the method alongside the number. A figure without its method cannot be checked, and an unchecked figure is how this community accumulates folklore.

Worth separating that from micronutrient cover, which this thread keeps folding into the same question. They behave differently and the advice does not transfer.

One thing that is still open after SarahChen_PharmD’s answer:

Was that from a primary source or from a summary of one?

Reporting back.

For the archive: it took about six weeks rather than the two I expected, and the difference between those two numbers was the whole of my problem.