Just what do you say when The Client tells you "the u looks odd"? Actually, I think you'll find it looks "odd" because it's not a u, it's a µ, as in µg, the widely recognised abbreviation for micrograms.
You might think that The Client, being a retailer of nutritional supplements, would be familiar with this, but in fact they list the dosage as 50ug on their own website (even though it is correctly marked µg on the label).
Telling The Client they're an idiot would not be politically expedient.