@Cloverys the answer is simple. it is quite unprecedented, why would they NOT hide the truth? if it was known, consider the consequences for her.. I for one cannot say for myself since I'm not the author but! it's a matter that could be bad.
Rule zero of an adventuring party with a chef. Don't fuck with them, they're the kings. they make your meals and ensure you're healthy. good food leads to good morale, good morale tends to lead to victory. plus being a chef, they tend to know how to prepare a dish juuuuust right to punish you.