This is interesting. I was just trying to research this because I also have Hashimoto's disease and had also read the study you posted.
Here are some natural herbs and supplements that may reduce prolactin:
A Chinese herbal formula (Liu Wei Di Huang Wan + Rou Gui, Yin Yang Huo and Huang Qi) was shown in a study to benefit female infertility due to pituitary dysfunction causing hyperprolactinaemia (one with and one without a pituitary adenoma). The medicine reduced the serum
prolactin
level, and resulted in a normal ovulatory cycle and pregnancy, without side-effects.
I think you can disregard all the female fertility stuff. The point is that these Chinese medicines reduce
prolactin
.
Also mucuna pruriens, P-5-P, NADH and DL-Phenylalanine because they help to increase Dopamine.