Vit B12 deficit without megaloblastic Anaemia??

Go to a Doctor first of all but I can give you a possible explanation that covers the entire problem you have.

First of all, you need to be aware of how B12 is absorbed. It is a water soluble vitamin that is unique because it requires an additional substance called Intrinsic Factor which is synthesised by the stomach, so it can be absorbed. IF binds to B12 for it to be absorbed. If you don't have Intrinsic Factor, some people suffer Pernicious Anaemia which is a megaloblastic anaemia subtype (although it is obvious that you're not suffering from it). This explains why your B12 levels are low but you are eating sufficient amounts of it (ie you may not have Intrinsic Factor).

Next point- Why is it that you do not have anaemia? The answer to this is quite complex. There is something called the folate pool or folate cycle. When you have folic acid, it enters a cycle that makes a particular type of folate, CTHF (no point in what it stands for). CTHF is used to make purines that are needed in cells that reproduce very quickly, such as red blood cells. If this substance is low then the cell division is affected (the DNA synthesis specifically) and the cells end up large and inefficent in oxygen exchange. The CHTF will also form methyl-folate which then requires B12 and methionine to revert back to a form that can reenter the CHTF pool. If B12 is low, then CHTF is also low and Methyl-folate will be exceptionally high. This will lead to megaloblastic anaemia.

The problem is that if you have folate in the diet, you will keep adding to the CHTF from pure folate instead of recycling using Vit B12. This will mask the anaemia artificially. Remember folate is added to a lot of things.

You may now ask... why then will low B12 affect me? This is because B12 is also needed for healthy nerves. Without B12 you will develop neuropathy and some of the problems caused are irreversible and can be fatal.

Funnily enough the description above is also the arguement some lobbists use to complain against folate being added to foodstuffs such as bread and cereal. Although higher levels of folate are needed in pregnant women and is good fo them.

I hope this helps and appreciate that this is difficult to understand.