Vitamin B12 and vegetarians

Having just had a medical check-up where my Vitamin B12 was measured for the first time.

Apparently, my level is 190 when the minimum should be 140 and the maximum should be 750

I am therefore somewhere near the lower limit, and one doctor recommended that I should take supplementary Vitamin B12.

The question however came up of my being a vegetarian and whether that might mean that my body functions fine without the high levels of Vitamin B12 found among non-vegetarians. Another doctor thought that I may therefore not need the supplement.

I don't like wasting money, but am commanded by God to look after my body, so I would appreciate any facts on the issue.