B-12 vitamin (bladder, doctor, stomach, cancer)

[WyattE]

I currently take one B-12 vitamin tablet a day, which contains 2000mcg. Although when I first started taking it, I could feel increased energy. Now after some months of taking it, I don't feel the energy anymore. I thought about taking two a day and see if that helps but not sure if that is recommended(at least the directions only say one a day). Can taking two a day harm my body? My brother gets a B-12 shot weekly and his doctor says your body will flush it out of your system each day.
Any feedback is greatly appreciated.

[Viralmd]

Unless you have a problem with your stomach, called achlorhydria (the stomach doesn't make acid) or have a lack of intrinsic factor, or have lived on tea and toast for a few years, you shouldn't need extra B-12. And, as a water soluble vitamin, what isn't needed goes out in the urine. It's not stored.

[Hopes]

Originally Posted by Viralmd

And, as a water soluble vitamin, what isn't needed goes out in the urine. It's not stored.

B-12 is stored in the liver. Roughly three to five years years worth.

You're right about one thing: the body does eliminate what it doesn't store.

What's not stored is eliminated through the colon, not the bladder.

B-12 overdose is considered nontoxic; however, there is a link between too much B-12 and certain cancers.

My knowledge comes from having a B-12 deficiency due to only having a partial intrinsic factor.