Folate or folic acid is referred to as vitamin B9, a key cofactor in one-carbon metabolism. Folate is the common terminology used for a group of molecules including folic acid, folinic acid or 5-formyltetrahydrofolate (5-FTHF), 5-methyltetrahydrofolate (5-MTHF) or L-methylfolate, 10-formyl-tetrahydrofolate (10-formyl-THF), 5,10-methylene-THF and unsubstituted tetrahydrofolate (THF).
Supplementation of folate is required to maintain adequate levels in mammals. Folic acid, folinic acid and 5-MTHF are different forms of folate that can be found in folate supplements1. The main differences between folate and folic acid is all about the forms in which they exist, folate is a reduced form while folic acid is an oxidized form. The reduced forms of vitamin B9 such as dihydrofolate and tetrahydrofolate are less stable biochemically, whereas the oxidized form, folic acid in supplements and fortified foods stays stable for a longer period of time2. Folic acid is a synthetic (man-made) water-soluble compound that does not exist in nature. It is comprised of a pteroyl group which is connected to a glutamic acid part and shows greater stability than the folates which are in reduced forms. In addition, folic acid depends upon 4 different conversion processes that need to happen within the body before it can become the 5-MTHF which your body can then directly absorb and use.
In contrast, Folate is a naturally occurring and comprised of polyglutamines in their tails. As compared to folate, folinic acid is also a naturally occurring compound in food, however, it is readily converted to THF even in the absence of dihydrofolate reductase (DHFR). Consequently, the effects of folinic acid are not affected by the drug compounds, for instance, methotrexate, which inhibits DHFR.
5-MTHF, naturally available, has metabolic advantages over folic acid and folinic acid. One advantage is that changes in the pH of the gastrointestinal tract do not affect the absorption of 5-MTHF. And the other is that the bioavailability of 5-MTHF is not interrupted by metabolic issues related to genetics or any metabolic-related diseases. So the supplementation of 5-MTHF rather than folic acid is advised to reduce the possibilities of masking hematological symptoms that occur with a deficiency of vitamin B12. Also, 5-MTHF is believed to reduce the probable adverse effects caused by unmetabolized folic acid in the human body. Several notions such as disruption in folate metabolism due to genetic shortcomings like methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms or any drug interactions, malabsorption syndromes such as celiac and Crohn’s disease, long-term medications (folate antagonists, antacids), alcoholism, poor absorption of ingested folate and low dietary intake, have been considered for folate deficiency in the human population. Folate deficiency has been treated by recommending folic acid supplements and fortified foods – even though this may be an inferior way to address the deficiency. Supplementing with the active form of folate, L-5-Methylfolate, is now preferred for obtaining optimal health benefits.