My doctor recommended me to take vitamin B12. Currently I have Colon Clitis and bleeding sometimes, and I'm vegetarian, so I need take B12. I'm taking some other supplements to keep me healthy. I didn't want anymore swallow type supplement. I chose this one, because I trust this brand, and this is Dissolve / chewable type. About if it work or not, I just started taking this, not sure if it works yet. *FYI, If you have Energy issue, it's not only you are not taking enough B12. There are many other reasons you should check; (1) Adrenal fatigue (you can google it for check list), usually it happens from stress. Too much caffeine makes thing worse. You can get Adrenal support supplement. (2) If your Thyroid working healthy or not. If you are not eating/getting enough Iodine, Selenium, Zinc and Copper, Thyroid doesn't make enough Hormone that our body needs. Blood work can be done to find out or you can find check list when google it. (3) If you have anemic from Colitis or other health issue. You may needs Iron too. (4) If you eat enough Protein. (5) If you getting enough Iron. (6) If you have Menopause, Menopause support supplement will give you energy back. (7) If you have depression