nismara, SW,
Interesting discussion. If I may relate first hand experience with B vitamins, and folic acid (B9, folacin) in particular. I may not be in the "normal" population to begin with, have excess calcium from sarcoidosis as background. In that context, I have tried a supplement containing all B's (for just the reason you mention, to keep my brain from shrinking) and in less than three months developed stomach problems. I made an appointment with a gastroenterologist a week ahead, suspecting that the B's were causing it, so I stopped taking them. Fast forward three days, things started to get better, by day six I was symptom free so I canceled my appointment.
Second, I had been taking folic acid (my employer hands it out at health fairs), and that was causing nausea, sneezing fits (histamine release), and a nasty drip that is not good for my lung condition, seems to keep O2 uptake down a bit, which I reported on in Lisa's thread:
https://www.physicsforums.com/showthread.php?t=418005". As soon as I stopped taking folic acid, the upset stomach, sneezing stopped, the drip was much better. I also added magnesium supplement, which helps in calcium be absorbed in the body. I again added folic acid (only for three days) and the same symptoms returned with a vengeance. I am off it for good now, convinced that that was the cause of my problem. I just had a stress echo-cardiogram and did way better than 4 years ago, got a level 4 this time, and did not feel like I was going to lose my breath at the end of the treadmill test. I was in better shape this time, and off all B's and folic acid as well.
I grew up believing B vitamins were "water soluble" and that for practical purposes you could not build them up in your system. I was on the B's for about a month and a half before developing stomach problems. I am now not convinced that they are "purged" from you system on a daily basis. The symptoms should have appeared at first, and did not.
I have two family members who died from alzeheimer's, my Grandmother, Father, it is not something I care to experience myself. Having said that, B vitamins and the bad side effects are too much. I am concerned that I may have the genes that given certain physical conditions my express themselves and I may develop it as well, but both Dad and Grandmother were smokers and moderate drinkers, Grandma more so than Dad. Plus later in life they became sedentary, I don't believe from any physical condition that would have prevented them from walking.
They were not very engaged with their minds either, both activities research has shown that slow the onset of the disease.
I plan on doing everything in my power to keep off the alzehiemer track. The brain book by Norman Doidge did provide a number of things (besides taking B Vitamins) that you can do to keep you healthy mentally, emotionally, and physically as long as possible. I will use every technique I can find. Might I suggest, as Doidge and a number of researcher's in the book provide case histories for, that engaging the mind seems to keep many elderly still quite with it, highly functional. In the end, it all comes down to personal motivation, and there isn't a pill I know of, yet, that stimulates that.
Rhody...
P. S. There appears to be 4 or 5 "histamine" receptor sites in the brain, it seems that the last two receptor sites from links I have been reading have only been detected in the past decade. Histamine must be fairly important for that many receptor sites and I have a bunch of links to try a fathom the history and will report in Lisa's thread in the future.