Pernicious Anaemia Society
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MTHFR - From the Horse's Mouth

Back in January 23andMe, the genetic testing company, wrote a blog post about the MTHFR gene. Their scientists had reviewed the available data and reached this conclusion...

Despite lots of research — and lots of buzz — the existing scientific data doesn’t support the vast majority of claims that common MTHFR variants impact human health.

And their recommendation...

Based on the existing data, scientists at 23andMe have concluded that people should not interpret their genotypes at the common MTHFR variants as having an effect on their health.

In order for a connection between a genetic variant and a health condition to be considered real and clinically meaningful, well-run scientific studies need to show convincing and consistent evidence for that association. As statements from multiple scientific and medical organizations indicate,[14] [15] that is currently not the case for the common MTHFR variants.

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Thanks, that's interesting to know.

One phrase set off a train of thought:

At one time, the "existing scientific data" showed that the earth was flat.

Presumably, "existing scientific data" showed that Thalidomide was safe for pregnant women.

"Existing scientific data" shows that it is only necessary (for people who have PA or are otherwise deficient) to have B12 injections every three months.

(I haven't had this genetic test by the way, so have no axe to grind in that respect!)


Sorry, but two out of three of your premises are incorrect.

There was never, ever, any scientific evidence for the Earth being flat. Ever since people started using the sea to travel moderate distances they've noticed that boats disappear beneath the horizon and realised this was best explained by a round Earth. When I was just 8 years old our class at school measured the diameter of the Earth using the method that Eratosthenes first used in 200 BC.

Yes, at the time the best knowledge gave no indication of the dangers of Thalidomide. That's why the way we investigate new drugs was changed - so that meaningful, well-run, scientific, studies were carried out to avoid such a problem again. Even so, we still have cases like Vioxx.

Finally, the case for three-monthly B12 jabs is, scientifically, on a par with the flat Earth. There is absolutely zero scientific evidence for this.

Neither 23andMe, or I, are saying that MTHFR does not cause health problems (in fact you'll often see me say that people with the C677>T homozygous mutation should at least experiment with methylfolate supplements). We're just saying that, despite a hell of a lot of looking, nobody has shown that to be true. That means it's either not happening, or it is a minor effect for the majority of those people (who are already a small minority) that have the mutations.


"Finally, the case for three-monthly B12 jabs is, scientifically, on a par with the flat Earth. There is absolutely zero scientific evidence for this."

Exactly :)

That was my point, however unskilfully made (not a scientist). Yet some people posting on this forum are apparently being told it is dangerous or unnecessary (by medical staff) to have injections more frequently AS IF this is scientific fact.

*Had a message from an admin asking me to clarify the above?

So, to clarify: I've read numerous posts here on HU over the last months/years from people who say they have been told by medical staff that they do not need, or should not have, or that it will be bad for them to have, B12 injections more often than 3 monthly. I haven't saved links to any of these so can't give specific examples. Hope that's clear enough.


Yes, it is true that many doctors seem to believe that there must be some real evidence for the 3-monthly regimen. But they have good reason for so thinking - because that's what it says in the BNF. You can't really expect them to trawl through the original scientific papers for every single entry in the BNF just to check it its correct.

So I don't blame the doctors, I blame the people who put together that entry in the BNF.

Tracey Wittey has made it her mission to try and get the medical establishment to admit that there is no scientific evidence for 3-monthly jabs and to get the BNF entry renewed.

It's a totally different situation than that for the MTHFR hype. Where certain naturopaths have been making a living telling people extrapolations and speculations that fly in the face of available evidence.


Frodo. That was me - I misread your post (foggy day) and mistakenly 'read' the suggestion (which wasn't there) that advice given on this forum was suggesting that three monthly injections were sufficient - and that any more was dangerous.

I realised my mistake quite quickly so went back and deleted my reply - which was obviously a complete misread of what you said.

Obviously I didn't delete quickly enough.

Perfectly recognise and agree that the medical position in terms of diagnosing, treating and managing B12 deficiency is, well...disgraceful (to put it mildly).

So...apologies for any foggy confusion (on my part). Hope that's clear enough 😄😄😄😄😄


P.s. You're here a lot so will perhaps recognise that I spend a great deal of time replying to people who are struggling to get treatment...and so hopefully recognise that this was a genuine mistake on my part.


Foggyme Totally recognise that! And always best to clarify if there's any confusion. All you admins do a great job. I don't know where I'd be without you and this group :)


Thanks Frodo - much appreciated.


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Eratosthenes, a Greek astronomer from Hellenistic Libya (276–194 BC), estimated Earth's circumference around 240 BC. He had heard that in Syene the Sun was directly overhead at the summer solstice whereas in Alexandria it still cast a shadow. Using the differing angles the shadows made as the basis of his trigonometric calculations he estimated a circumference of around 250,000 stades. The length of a 'stade' is not precisely known, but Eratosthenes's figure only has an error of around five to fifteen percent.[22][23][24] Eratosthenes used rough estimates and round numbers, but depending on the length of the stadion, his result is within a margin of between 2% and 20% of the actual meridional circumference, 40,008 kilometres (24,860 mi). Note that Eratosthenes could only measure the circumference of the Earth by assuming that the distance to the Sun is so great that the rays of sunlight are essentially parallel.

Thanks Wiki.


Well all I know is the fact I’m homozygous for a1298c is the only clue I have ever been given about why my body doesn’t handle b12 the way it should, why my MCH and MCV are always high, why my homocysteine is sometimes elevated. Doctors just say - oh, don’t worry about that. We don’t know why. I have IBS and depression as well. I’m not going to take crazy supplements - just my usual b12 and methylfolate. But it gives me a clue as to what is going on.

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