vitamin b12 deficiency
"I lacked the intrinsic factor to absorb Vitamin B12 from food since I was in my 30s. I was diagnosed with breast cancer 2x and now am age 55 I increasingly find that I am dependent on the b12 for energy, mood and weight maintenance. I can tell when my levels are low without a calendar as this usually occurs about 3-5 days before the end of the month when I am do for my shot."