So I’ve only just seen this thread for the first time.
The opening post has three quotes; the second two quotes, with general info about levomefolic acid and the need for MTHFR to convert folic acid into it, are from Wikipedia, as the post implies.
The first quote, however, with the claim that 50% of the population converts “only a limited amount” of folic acid into levomefolic acid is unsourced, and does not appear to come from wikipedia - or any other reliable source I can find.
The facts I find are as follows:
People with the CT mutation covert folic acid at 30% reduced efficiency, and people with the TT mutation convert at 65% reduced efficiency. This does not limit the amount of folic acid that gets processed to some fixed figure, it reduces the rate. If a person with TT is showing low folate levels in their blood, they need to increase their folate intake to compensate for the lower conversion rate. This simple therapy has proven to be very effective.
It’s important to know this:
All naturally occurring folates in foods and folic acid all fall into the same “loop” in one of the body’s metabolic cycles. The loop is subject to the MTHFR enzyme process, which is part of the loop, so if you’re at a reduced conversion rate, it’s true for both “natural” and “synthetic” forms. Consuming a particular form puts you in a particlar part of the loop, but most things in the body get recycled a lot. They’re in the same loops.
So if you have this mutation, which slows all folate conversion, there is no special “natural” food or supplement to help or bypass it. The best bet is to simply consume extra folate, in any form, to compensate for your low conversion rate.
Any supplement providing levomefolic is likely synthesized, just like folic acid. While it may, in glutamate form, be one of many folates that can naturally occur in food, it is apparently not a major one - I can’t find reference to foods high in levomefolic acid. It is generaly considered a synthetic form:
The terms folate and folic acid are often used interchangeably for this water-soluble B-vitamin, which is also known as vitamin B9 or folacin. Naturally occurring folates exist in many chemical forms; folates are found in food, as well as in metabolically active forms in the human body. Folic acid is the major synthetic form found in fortified foods and vitamin supplements. Other synthetic forms include folinic acid (Figure 1) and levomefolic acid.
Incidentally, “folate” is generally a catch-all term for all the chemicals that lead to folic acid in your body - so folate includes the naturally-occurring substances in foods which your body converts to folic acid, and it includes natural/synthesized folic acid. They’re all “folate.” Different groups of people have different definitions of “folate” - food scientists vs. medial doctors vs. chemists. Reputable sources define what they mean by “folate” if they’re using the term.
The fact that folic acid and levomefolic acid are sythesized does not make them bad - the folic acid sold in supplements may be chemically synthesized to produce it, but the resulting molecule is identical to the folic aid produced in your body’s cycles from naturally occurring folates. More importantly, pure folic acid is much more bio-absorbable than than naturally-occuring folates. It’s inexpensive, chemically identical, very absorbable, and easily addresses low-folate problems.
Since both folic acid and levomefolic are natural in the sense that they are produced in the human body, but both are synthesized as supplements, be wary of any source fixating on the idea that folic acid is “synthetic.”
Note, also, the critical fact that the RDA level is set in such a way that the majority of the population shows no signs of folate anemia. Ten percent of the population has the TT mutation and therefore much slower conversion of folate - the RDAs are never set in such a way that 10% of the population remains deficient! It’s intended to be a level which meets the needs of at least 97.5% of the population. The current RDA is high enough to bring all or most of the TT-mutation people into sufficiency, but it may be at a “borderline” level. (There are also other problems which leads to folate insufficiency, contributing to the 2.5% of the population for whom the RDA is not quite enough.)
There is some debate about raising the folate RDA even further, to ensure that such people are not “borderline.” There is also a well-established practice of giving pregnant women ample folate in their pre-natal vitamins to ensure that they do not have any deficiency during this time of elevated need.
Lastly, the standards have recently been revised to include the concept of DFE - Dietary Folate Equivalent. This is specifically because we have firmly established that folic acid is much more effective at meeting the body’s need for folate than naturally occurring folates in food.