Maca affects the pituitary and the hypothalamus which release hormones that affect thyroid functioning. Hence, in the case of hypothyroidism wherein, there is a deficiency of the thyroid hormone, maca might increase the output by stimulating the centers in the brain.However, maca does not directly affect the thyroid and in fact, people suffering from hyperthyroidism should refrain from using maca as it might further deteriorate the symptoms.