Black henna can contain many things except henna. It is likely to contain indigo or other more permanent dyes and it's not safe, it can cause allergic reactions in many cases. Normal henna leaves a brownish color. I'm not sure where you are or what your means are but home hair dyes are a much better alternative.
Prior to the availability of the pure levothyroxine, desiccated animal thyroid extract was the only treatment for hypothyroidism. Today, some individuals prefer dessicated thyroid extract as a more natural thyroid hormone.
Thyroid Assist contains Bladderwrack, a sea vegetable that is a prime source of iodine, an ingredient that is crucial in the activation of thyroid hormone production. It is also used for healthy metabolism and can be found in many slimming remedies.