sciencedirect.com/science/a...
This article focuses on the role of b12 and folate in the synthesis of methionine and one of the side effects of improper synthesis is depression and cognitive impairment.
However, I want to emphasise that poor synthesis of methionine impacts protein production and the production of many other critical molecules.
Methionine
is an amino acid that produces several important molecules in your body. These molecules are essential for the proper functioning of your cells.
It is involved in the production of cysteine, the other sulfur-containing amino acids (such as Sam-e) used to build proteins in the body.
Cysteine, then produces antioxidant glutathione and Taurine
- Glutathione is sometimes called the “master antioxidant” due to its critical role in the defenses of your body
It also plays a role in the metabolism of nutrients in the body and the production of DNA and proteins
- Taurine has many functions that help maintain the health and proper functioning of your cells (8Trusted Source).
SAM-e
One of the most important molecules methionine can be converted into is S-adenosylmethionine, or “SAM”
SAM participates in many different chemical reactions by transferring part of itself to other molecules, including DNA and proteins (3, 9
Trusted Source
).
SAM is also used in the production of creatine, an important molecule for cellular energy
SAM can change your DNA by adding a methyl group (a carbon atom and its attached hydrogen atoms) to it
The amount of methionine in your diet may affect how much of this process occurs
healthline.com/nutrition/me...
If this is all too deep, just glean from it that b12 and folate are so critical in cell generation, impacting DNA synthesis, brain cells, nerve cells and our metabolic process for producing energy.
Folate and B12 levels
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advice please b12/folate 
B12 and Folate test results
Updated B12 and folate results
