L-Methylfolate vs folic acid

March 31, 2019 9:36 PM

What dose of l-Methylfolate is equivalent to 400 mcg of folic acid?

Recommendations provide dosing guidance for folic acid (or “folate” standing for folic acid), but not for L-Methylfolate (which is supposed to be more bioavailable).

Thank you in advance!

posted by cotton dress sock to Science & Nature (7 answers total)

This comparison study used 113µg doses of L-MTHF as calcium salt (Metafolin) and 100µg doses of folic acid on the basis that these doses are equimolar (i.e. contain the same number of folate molecules).

The study results show that this dose of L-MHTF resulted in a slightly better reduction in total homocysteine (tHcy) concentrations and slightly lower plasma and red blood cell folate concentrations. This is what I'd expect given that folic acid needs to be metabolized by the liver before becoming active.

Since the differences in these results are not huge, and since the lowering of tHcy is the effect you're actually after and is slightly better for the more immediately available L-MHTF, it seems to me that trying to compensate for L-MHTF calcium salt molecules being 13% more massive than folic acid molecules is probably a waste of time and that the sensible thing to do would be to treat 400µg doses of either as near enough to equivalent.
posted by flabdablet at 11:32 PM on March 31, 2019 [1 favorite]

Response by poster: Thank you for the research! (Actually, if it helps - the effect I’m after is prevention of possible neural tube defects in a potential fetus. There are reasons to avoid folic acid, and I haven’t been able to find firm guidelines on dosages of L-Methylfolate for this purpose, largely because research on probabilities re that exact outcome would be unethical. Prenatal vitamin formulations exist, often with 800+mcg of Methylfolate, but the idea is to have neither too much nor too little of it, not what a marketer thinks will sell.)
posted by cotton dress sock at 12:12 AM on April 1, 2019

the effect I’m after is prevention of possible neural tube defects in a potential fetus

Mayo recommends 400-800µg daily for that. And if you're getting something like 250µg/day from food as this study of folate intake in Europe suggests is typical for women, supplementing with 400µg/day of either folic acid or Metafolin would put you pretty much right in the middle of the recommended range.

Some people have a metabolic defect that makes supplementation with about ten times the usual amount necessary, but that's something to discuss with your doctor rather than the Internet.
posted by flabdablet at 3:58 AM on April 1, 2019 [1 favorite]

More on the metabolic impairment thing:

Women at higher risk need more folate (under medical supervision!)
Folic acid metabolism and mechanisms of neural tube defects
posted by flabdablet at 4:11 AM on April 1, 2019

Response by poster: I’m familiar with the above, thank you.

The mentioned range refers to folic *acid*, though, or dietary folate, not specifically L-Methylfolate.

My question is how much L-Methylfolate is equivalent (accounting for pharmacokinetics) to 400 mcg of folic acid.
posted by cotton dress sock at 5:27 AM on April 1, 2019

I would ask this question of a pharmacist and/or doctor. Folic acid is considered very important for anyone who is looking to conceive - you'll want to be sure that the alternative is both the correct dose and effective for the prevention of neural tube defects.
posted by jb at 5:37 AM on April 1, 2019

Best answer: The pharmacokinetics of conversion will depend on your individual MTHFR polymorphism status.

This study compared a medical food L-methylfolate + folic acid, to a multivitamin containing folic acid alone. Several cautions as it was retrospective, unmatched, polymorphism status differed, etc etc, but from the full text: "The prenatal medical food with or without DHA contains 1.13 mg of L-methylfolate in addition to 0.4 mg folic acid, whereas PNVs contain 0.8 to 1.0 mg of folic acid alone."
posted by basalganglia at 9:21 AM on April 1, 2019 [1 favorite]