You are in luck, I had the same question last week and I took the time to email all the UC's plus Stanford. General consensus is at least one science LOR. Out of the three UC's that replied, only UCSD seemed to want two letters of rec from science professors, but I don't trust the email I got. Perhaps someone with an UCSD secondary can tell us. I would also like to know for UCLA and UCD, since they have ignored my emails.
Here are the actual email replies:
I ask: do you specifically require that two letters of recommendation come from science professors?
Stanford (first to reply, as expected):
No. Please select recommenders that know your work well. (academic, research etc.)
UCSF:
We do not require that letters come from science professors. We do require that letters come from the premedical or advising office at your school if there is such an office.
UCSD (without actually answering my question):
Yes, two letters should come from professors that taught you.
I followed up: Science professors?
UCSD: Science professors.
UC Irvine:
It is suggested that two letters (at least one from a science professor) be
submitted by senior professors
UC Davis: No response (been two weeks)
UCLA: (Out of Office AutoReply) Thank you for your inquiry about the UCLA School of Medicine admissions
process. You will receive a personal response within a couple of days.
No response (been two weeks)
