Not yet investigated
What we have so far
It genuinely changes with diet, which is why the test strip is the industry's favourite prop. It reports what the kidney excreted, not what the blood is doing.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.