This has little to do with b12 but will ask here. I heard people who don't absorb fat can have pn issues. I'm wondering though now I do if after 12 years of being malnurished with little dietary fat could still be effecting now but just doesn't show? How and what would be helpful? This past years since I got healthier let me tell you how thick my hair is and my skin is not so dry and grey. I do wonder though the intrernal issues though my bllod work is good though high liver and low white blood count. I'm one of the high b12 people with 1500-2000 range. Actually on the b12 note since I am 29 would the need be different? I don't get it what you mean over 50 is there different levels for different people. Also I know b complex has other b vitamins but why is it needed? Lastly I thought a lot of the nail issue is from calcium? Ok now enough.Thanks so much