In order for folic acid to remove homocysteine, it first must be converted to its active form called L-methylfolate (5-MTHF). 

Magnafolate®  is the existing form of folate in human blood circulation, the metabolite of folic acid. It is the only endogenous 5-methyltetrahydrofolate that can cross the blood-brain barrier and the blood-retinal barrier and can directly act as a methyl donor. Without conversion, it can be directly absorbed and utilized. It is the best form of active folate.

Magnafolate^® is the patent protected C crystalline L-5-Methyltetrahydrofolate Calcium salt (L-5-MTHF Ca) which is invented by Jinkang Pharma from China in 2012, produced under US Patent No. 9,150,982 B2. 
The preparation of the Calcium salt and the crystal type C solved the stability problem completely. It has the highest purity more than 99%, and controls some potential risky impurites to the smallest assay.
Such as Mercury 0.1ppm, 15 times less than USP standard 1.5ppm
JK12A 0.1% , 10 times less than USP standard 1.0%
D-5- Methyltetrahydrofolate 0.1%,  10 times less than USP standard 1.0%
Importantly, we avoid using the toxic raw material of formaldehyde during production process compared to other marketing  generic L-methylfolate.

Now, Magnafolate ® has been well approved in US GRAS, NDI and FDA.