[MonikaT]

One other area you might look into for lack of energy is your Iron level. Adding som B12 has appreciably helped my energy level.

My B12 level is actually kind of high from using supplements, and my medical practitioner has told me to reduce the dose I was taking. My iron level tends to run just a little bit lower than the low end of the normal male range, but nobody seems concerned about it. My vitamin D3 is also near the bottom end of the scale even after taking 12,000 IU a day.