It is not rare.
Depending on ancestry, a large share of people carry at least one copy. A variant this common is ordinary human variation — not bad luck you have been singled out for.
Folate · the form question
Most folate sold in the US is folic acid — a starting material your body has to convert before it can use any of it. Here is how that conversion works, why the last step runs slower for a large share of people, and how to tell in ten seconds which form is in your bottle.
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01 · The part nobody mentions
You bought the multivitamin. Maybe a B-complex as well. You take it in the morning with water, most days, for months. It is the least dramatic thing on your list and you never think about it again.
Which is the whole problem. A supplement is the one purchase that never reports back. Nothing beeps. Nothing fails. If the folate in that capsule never finished the trip into a form your body can actually use, the bottle empties at exactly the same rate.
So this page is about one word on the back of a label, and what has to happen inside you after you swallow it.
It passes through several enzyme steps before it becomes 5-MTHF — the main folate circulating in your blood. L-Methylfolate is that finished form.
Nothing on this page asks you to believe that folic acid is harmful. The question is narrower, and answerable: how much work is left to do after you swallow it.
02 · The mechanism
Folic acid is synthetic and shelf-stable. That is why it is in almost everything. It is not the folate your cells run on, and getting from one to the other is a relay — every leg needs its own enzyme.
Route A · what folic acid has to do
Route B · what L-Methylfolate does
The gate. MTHFR is the enzyme at that last step — the one the gene is named after. Route B lands on the same molecule without ever reaching it.
Simplified — folate metabolism has more branches than this. These are the steps that decide the form. [1]
03 · MTHFR
MTHFR is the instruction for building the enzyme at that last step — the one that finishes folate into 5-MTHF. Almost everybody has the gene. What differs is which version you inherited.
The common variant is called C677T. Inherit one copy and the enzyme it builds runs at roughly two thirds of typical speed in laboratory conditions. Inherit two and it is closer to a third. The enzyme still works. It works slower.
Slower is not broken. It does mean the last leg of the relay is the narrowest part of the road for a lot of people — and it is the exact leg you skip when you take the finished form.
Roughly how 100 people split
How fast the enzyme then runs
The enzyme still works in every row. What changes is how quickly it finishes the last step.
Left: midpoints of published ranges, not a measurement — around 20–40% of white and Hispanic Americans carry one copy, and roughly 8–20% of people across North America, Europe and Australia carry two. It is far less common in people of African descent. Right: enzyme activity measured in laboratory conditions — a measure of an enzyme, not of how anyone feels, and not a prediction about an individual. [2] [3]
04 · What is actually true
Depending on ancestry, a large share of people carry at least one copy. A variant this common is ordinary human variation — not bad luck you have been singled out for.
The CDC is explicit: people with an MTHFR gene variant can process all types of folate, including folic acid. The difference the research describes is efficiency, not a wall. [3]
A test tells you your genotype. It does not change the fact that 5-MTHF is the form your body was going to make anyway. If you would rather not depend on the conversion step, you can simply skip it.
We sell methylfolate. We would still rather you had the accurate version.
05 · Downstream
5-MTHF's job is to hand over a methyl group — one carbon and three hydrogens. That handoff turns homocysteine into methionine, and methionine into SAMe: the molecule your body uses to methylate almost everything else, including DNA and the pathways that build neurotransmitters.†
Simplified. 5-MTHF is the main folate circulating in blood and the folate form that moves into the brain.† [4] [5]
None of this is exotic. It is the ordinary machinery that decides whether a Tuesday afternoon feels like something you can get through.
Why the form is worth four minutes of reading
06 · The conversion ceiling
The first enzyme in the relay, DHFR, is slow in humans and easy to saturate. Past a certain single dose, folic acid begins showing up in the blood still unconverted. Researchers call it unmetabolized folic acid — UMFA.
The thresholds are lower than most people expect, and what UMFA means for long-term health is still argued over. We are not going to pretend it is settled. The useful point is simpler: taking more of the starting material does not make the conversion step any faster.
Bar length is illustrative, not a measured curve. What unmetabolized folic acid means for long-term health is still debated; we are not going to tell you it is settled. [6] [7] [8]
07 · Check your own bottle
This is the part you can do right now, before you decide anything about us. Go and get whatever you already take. The word you are looking for is on the back.
Folinic acid is a real folate and a legitimate ingredient; it simply still has a step to go. None of these are dangerous, and none of them are disqualifying. The only question this table answers is which of them arrives finished. [1]
08 · What we made
Clean Health Lab Maximum Strength L-Methylfolate is 15 mg of active 5-MTHF and 220 mg of glycine in a small vegan capsule. That is the entire formula — no proprietary blend, and no second page of ingredients.
09 · Why 15 mg
Most methylfolate on the shelf is 400 mcg to 1 mg, sized against the Daily Value — a number that exists to cover a population's baseline needs.
15 mg is a different order of magnitude, and it is deliberate. It is the strength used in the published clinical research on L-methylfolate, where 15 mg a day separated from placebo and 7.5 mg did not. [9]
What that research actually was, plainly: two trials of L-methylfolate taken alongside a prescription antidepressant, in patients under a clinician's care. That is a different setting from a supplement bought online, and we are not claiming its results. It is simply where the number 15 mg comes from — and we would rather you knew that than assumed something better.
This is a dietary supplement, not a medicine. We are telling you where the number came from, not what it will do for you. If you are pregnant, nursing, taking prescription medication, or simply unsure, talk to your provider before starting. At this potency that is the honest advice.
400 mcg × 37½
the dose most methylfolate bottles carry
15 mg × 1
one Clean Health Lab capsule
15 mg is 37½ times a 400 mcg dose. On the label that reads 25,000 mcg DFE, 6,250% Daily Value. This is a deliberate high-potency dose, printed plainly on the front rather than buried in a blend. [9]
10 · The panel, in full
Set below as text, transcribed from the panel printed on the bottle you receive. Folate is listed as 25,000 mcg DFE — Dietary Folate Equivalents, the unit that lets different forms of folate be compared on one scale.
Glycine is the only other named ingredient. It is a simple amino acid doing the job of a carrier.
Supplement Facts
Serving Size 1 Capsule
Servings Per Container 60
** Daily Value (DV) not established.
Other Ingredients: Vegan Capsule
Suggested Use: For adults, take one (1) capsule daily.
No fillers · No stearates · No silica · No flow agents
† These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
11 · Who this is for
12 · What people say

“I found out I carry an MTHFR variant and switched that week. Taking the form my body doesn’t have to convert is the reason this is the one supplement I don’t second-guess.”Priya N.Order-linked review · July 2026

“I’ve taken a folate for years without thinking about it. This is the first time I understood the difference between folic acid and the active form.”Renee C.Order-linked review · July 2026

“I’d been told to look for a methylated folate and had no idea where to start. The label spells out the form and the dose, so I could check I was getting the one I wanted.”Theo B.Order-linked review · June 2026
The photographs above are our own product photography, not pictures of the people quoted. The quotes, names and dates come from the order-linked review record.
13 · The offer
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$50.99every 2 months
No commitment
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60 days from delivery · Free return shipping · Full refund
You do not have to finish the bottle to qualify, and you do not have to explain yourself. If the form was not the thing standing in your way, we would rather you had your money back than a cupboard full of capsules.
14 · Questions
No. A test tells you your genotype; it does not change what the finished form is. Plenty of people test out of curiosity, and plenty never do. It is not a prerequisite for choosing a folate.
Almost certainly not. Most multivitamins use folic acid. Turn your bottle over and read the panel — if it says folic acid, that is the starting material rather than the finished form.
Many people do. But at 15 mg this is a high-potency single nutrient, not a maintenance dose, so ask your provider first — especially if you take prescription medication.
Many people describe a change over three to six weeks. Some notice nothing at all. Individual responses vary and we are not going to pretend to know yours in advance.
It is a deliberate, high-potency dose, and it is printed plainly on the front of the label rather than buried in a blend. Whether it is the right dose for you is a conversation to have with your provider.
Send it back. The 60-day money-back guarantee starts at delivery and return shipping is free. You do not need to finish the bottle to qualify.
The form is the part you can control
You did not pick which version of MTHFR you inherited. You do get to decide whether the folate you take still has a conversion step standing in front of it.
See the label and the price — $50.99 → 60-day money-back guarantee · free return shipping · free shipping on subscriptions · cancel anytimeSources