How B12 Deficiency Affects Hashimoto's Dr. Izabella Wentz Vitamin B 12 Injections In Hamilton Estetica MA Cyanocobalamin (B12) Products American Regent Benefits of B12 Injections for Optimal Health Symptoms of vitamin b12 deficiency. Studies show that low levels of vitamin b12 may be more common in people with hypothyroidism. Vitamin b12 is also involved in making and metabolizing thyroid Our bodies need vitamin B12 to maintain healthy red blood cells, nerves, and brain function. If a person has vitamin B12 deficiency (their body does not have enough vitamin B12), they can