Methylcobalamin (Methyl B-12) is better absorbed and retained than other forms of B12 (such as cyanocobalamin.) Methyl B12 protects nerve tissue and brain cells and promotes healthy sleep. Methyl B12 is a cofactor of methionine sythase, which reduces toxic homocysteine to the essential amino acid methionine. Methylcobalamin also protects eye function against toxicity caused by excess glutamate.