The human body needs folate, or vitamin B9, for several essential functions. Folate activates, synthesizes, and repairs DNA. It converts homocysteine, which you don't want too much of, into methionine, an essential amino acid. Vitamin B9 also aids cell division, is required for red blood cell production, stimulates neural transmitters, and is essential for proper fetal development. Needless to say, you need this stuff.
What is Methylated Folate?
To take it a step further, methylated folate is the active, natural form of folate that the human body uses. The body cannot produce folate, so it must be obtained through diet. Note that the folate provided by food is not biologically active; it must be broken down by the liver. This process creates tetrahydrofolate, or methyl folate, the form of folate your body can use.
What About Folic Acid?
Folic acid is the synthetic form of folate. Synthetic folic acid has been used to fortify foods for years in North America. This was started in an effort to reduce the chance of neural tube defects in developing fetuses. In that time, several concerns have been raised regarding its safety and effectiveness. Researchers have determined nearly 50% of the population have a genetic variation that prevents them from receiving any benefit from folic acid, or only converting a small amount of folic acid. This variation is known as MTHFR.
Why Has Methylated Folate Become Popular?
Methyl folate, or 5-methyltetrahydrofolate, has become a popular option for folate supplementation. One of the reasons for this is because unmetabolized folic acid in the blood stream has been associated with reduced immune function.  Synthetic folic acid has also been found to mask vitamin B12 deficiency.
Methylated folate eliminates these concerns. Research has shown that methyl folate can deliver folate immediately, without the need for conversion.  It also does not mask B12 deficiency and has no consumption intolerances.  This offers an effective alternative for folate supplementation for everyone, including those with the genetic MTHFR factor, and especially pregnant women.
Methylated Folate: A More Effective Supplement
As synthetic folic acid has been proven to be an ineffective folate alternative for nearly half the population, methylated folate has been used to support a range of health concerns, including…
- Mood disorders - Methyl folate represents a better option for patients due to its greater bioavailability and lack of side effects. 
- Homocysteine reducer - A folate enriched diet, or supplementation with bioavailable methyl folate has been shown to lower homocysteine levels, an amino acid associated with a higher risk of cardiovascular concerns. 
- Diabetic peripheral neuropathy - A randomized, double-blind, placebo-controlled trial found that patients with diabetic neuropathy experienced quality of life improvements with methyl folate. 
- Skin disorders - A recent 2013 study found high proportions of methyl folate in the epidermis, even as serum folate levels dropped. This has suggested it as a potential UV skin protectant and an option for skin conditions such as psoriasis. 
- Prenatal supplementation - Methyl folate supplementation ensures adequate folate levels necessary to support normal neural development.
Supplementing with Methylated Folate
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†Results may vary. Information and statements made are for education purposes and are not intended to replace the advice of your doctor. If you have a severe medical condition or health concern, see your physician.