This is an excerpt (not recommended if on the birth control pill):
The research showed that taking vitamin C along with levothyroxine reduced TSH levels substantially, by as much as 27%. Taking the levothyroxine along with 1 gram of vitamin C mixed with water over a period of six weeks was able to help the majority of patients achieve their TSH target level (and also antibodies in one person who posted).
Dr Barry Peatfield also recommends taking Vitamin C
A research article of (I believe) 1975