High MCV with low B12

by Greg
(Idaho)

I recently had a blood workup, and my MCV and MPV levels were both high. 94 on the MCV. I'm 60 years old, and looking back over the years since 1995, my MCV typically runs from 90 to 101. However, recently the upper limit has dropped to 92, therefore, the 94 stood as an outlier.

My physician was astute enough to see this and said "let's do another blood test to check for B12 deficiency". Test came back with B12 levels 382; low end of normal.

I did a bit of internet research, and sure enough, I have a few (1 mo to 1 yr) of the typical symptoms of B12 deficiency.

I'm athletic, getting plenty of aerobic exercise (but not overdoing it). No prescription or other drugs, don't smoke, very minimal alcohol usage. We eat pretty healthy, not much red meat. No concerns about heart disease, etc.

I take a few vitamins daily (multi, calcium, etc), and a baby aspirin dr recommended.

So, my questions:
1) Is it likely that I have been B12 deficient for decades?
2) If the recommended daily amount of B12 is 6 mcg/day, why am I prescribed 1000 mcg/day for six months to bring B12 values into the nominal 600's range?
3) I've read that aspirin can interfere with B12 absorption. I'm considering dropping the daily baby aspirin. Yes?
4) If my B12 levels come into normal ranges, would my past and future normal eating B12 intake at, say, 12 mcg/day suffice?
5) How long does it take for the typical person to drop from a nominal B12 level with these large supplements to their deficient level without taking the supplements?

Thank you!