This has been posted by Thyroid advocate Mary Shomon
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. The researchers concluded that vitamin C can enhance oral absorption of levothyroxine, and taking vitamin C along with levothyroxine medications should be considered in patients with difficulties in the absorption of levothyroxine.
http://thyroid.about.com/b/2009/03/26/t ... amin-c.htm