Ultra Preventive X by Douglas Laboratories 240 VegCap Ultra Preventive X 240 Veg Cap Product Douglas Laboratories is proud to announce that Ultra Preventive X now contains Metafolin a patented natural form of (6S) 5- methyltetrahydrofolate (5-MTHF) as well as 1 000 IU of vitamin D3 per serving. 5-MTHF is the naturally occurring predominant form of folate commonly found in cells and is essential for overall health as it participates as a cofactor in a reaction that involves the remethylation of homocysteine to methionine. Unlike synthetic folic acid 5-MTHF can be used directly by the body without the need for an additional conversion via the enzyme (5 10- methylenetetrahydrofolate reductase (MTHFR)). In certain populations the bodys ability to convert folic acid to 5-MTHF by use of this enzyme may be compromised due to genetic differences. Metafolin contains only the S isomer of 5-MTHF and has been shown to be the only form of folate to be able to cross the blood-brain barrier.