Whether your hair turns gray and falls out or stays a thick mane of vibrant color is dependent on your body having proper levels of thyroid hormones.  A common issue for those plagued with hypothyroidism is fine, dry, slow-growing and/or thinning hair. When your thyroid is not functioning up to par, the body will attempt to conserve energy by redirecting it from nonessential areas, and directing efforts at repair and regeneration to those functions considered more essential. This is why the beauty of your hair and skin are among the first to go then your thyroid starts to give out. And when the thyroid function is low, intestinal absorption and utilization of nutrients is compromised. There are then not enough raw building materials available to keep the nonessential parts of you at their best.