Food for thought: At what levels is B12 absorption best?

[Korn]

http://www.vegansociety.com/phpws/in...N_position=7:5

"Homocysteine rises significantly long before B12 stores drop to the level associated with classical B12 deficiency. Current UK Government recommendations of 1.5 µg per day are based on reliably preventing classical deficiency and are more than adequate for that purpose. However, they do not take into account B12 requirements to minimise homocysteine. At least 3 µg per day are required to achieve this by maintaining blood B12 levels at 300 pmol/l or more. If the main source of B12 is a supplement taken daily, at least 10 µg should be taken. If it is taken weekly, 2000 µg is required. The variation in recommended weekly intake is because absorption of B12 is best at small doses below 0.5 µg, where about 70% of available B12 is absorbed. As the dose approaches 10 µg, the amount absorbed flattens off at about 1.5 µg and only about 0.5% of further increases in dose are absorbed. The absorbed amount from 2000 µg is therefore little more than 10 µg, which is just enough for one week, while the same absorbed amount can be obtained from 3 µg per day spread across several meals or from a daily supplement of 10 µg. "

As you may know, there is a lot of discussion both regarding how much B12 we need pr. day and about the B12/homocysteine/heart disease issue, but it's nevertheless interesting that 'absorption of B12 is best at small doses below 0.5 µg, where about 70% of available B12 is absorbed. As the dose approaches 10 µg, the amount absorbed flattens off at about 1.5 µg and only about 0.5% of further increases in dose are absorbed.'

The absorbed amount from 2000 µg is therefore little more than 10 µg.
As you can read about in another thread, there are other ways to reduce homocysteine levels than by taking B12.


(µg = microgram)

[1vegan]

I've read some b12 articles on this forum, and I'm afraid that even if english was my first language (what it isn't) the articles/ opinions / research would still be beyond my capability of understanding.

And cause I don't take b12 every day, and don't use "fortified" products, I would say that the 1000 microgram nuggets (solgar) are the most efficient for me.

That way, I'm reasonably sure I get enough per week.

B12 shortage can have effects that are too serious to play with.

Better to be safe than sorry, that's one of my motto's

[Korn]

One of my mottos are 'Better to be sorry than feel that you are safe when you're not'. Actually, the method you have chosen is one that very few will agree is the best one ( - but which I'm nevertheless sure many follow).

Solgar suggests their 1000 mcg nuggets as a daily supplement, so they will say you don't take it often enough. (I don't agree with their view on B12...). Stephen Walsh / The Vegan Society will suggest that if you take B12 weekly, 2000 mcg is required). (I don't agree with their approach to the B12 issue either). I live in Norway, which has relatively high medical standards (everything is relative, as we know) - here you can't even buy stronger B12 supplements than 9 mcg B12 pr. pills without a doctor's prescription... Everything above that is considered 'therapeutic amounts'.

Nature's way seem to be to consume a little B12 with every meal, from food, and to expose yourself to as little B12 reduction as possible. Very little is needed pr. meal, (as the initial post in this thread says, B12 absorption is best at 0.5 mcg pr. intake, possible even less.)

Some sources will claim that there are no known toxic side effects of taking too much B12, but they seem to not know about or ignore that high B12 levels are associated with certain forms of cancer. (Too little B12 is also associated with higher cancer risk). I consider the late B12 guru Victor Herbert in many ways a not reliable source. He did what he could to make vegansim and 'everything alternative' look risky and unprofessional. He wrote that healthy people need 0.1 mcg B12 pr day - and believe me, if he could have written that we need a lot more with scientific support, he would, because he seemed to love to put veganism in bad light, and plants contain less, in many cases no - B12. So if he could make it look like the B12 levels that exists in plants are even further from what we need daily than the case is, I'm convinced that he happily would have done that. He didn't (the homocysteine issue is related to this, but that's another thread).

Meat eaters, who actually consume the blood, muscles, liver etc. of other animals, have an average intake of maybe 5-7 mcg daily. Absorption from supplements should be 'easier' than from food, because the B12 already is 'ready to travel'.

Have you actually checked your levels? I don't remember if you mentioned how long you have been vegan, but as you might know, the over-consumption of B12 among non/pre-vegans might have created reserves that will last for several years.

[Korn]

Some more info on B12 absorption rates:

First, a little comment about the myth about liver being a great B12 source for non-vegans... what many people don't know, is that only 11% of the B12 found in liver is actually absorbed, even less than in eggs, where circa 30% of the B12 is absorbed.

The more B12 you eat, the less of it (percentwise) you'll absorb.

If you consume a supplement containing 50 mcg B12, studies show that you'll absorb about 3% only. Studies also show that if you consume 10 mcg B12, you'll absorb 15-16%. This means that you'll absorb circa 1.5 mcg B12 in both cases. Another study shows that you'll absorb circa 5% B12 if you take a supplement containing 25 mcg. Looking at these particular studies, you'll absorb more B12 from 25 mcg tablet than from a 50 mcg tablet!

Looking at more studies, you'll find that if you consume very small amounts of B12 (studies that have been performed on levels between 0.1 mcg and 1 mcg), you'll absorb somewhere between 50 and 90% of the B12 you eat. It seems that we are 'designed to' absorb B12 at very low levels, but to do it often.

If our soil and water wouldn't have been in a constant fight with B12 killers, and if we would have been eating fresh plant food, we'd probably have gotten a lot of B12 in small amounts, several times a day; which is the best way to absorb B12. At high B12 intakes, we aborb almost none of the B12 we eat: If we take 50 mcg B12 we absorb 3%, and if we we eat a 1000 mcg B12 supplement, we absorb only between 1 and 1.5%. 1-1.5% is 10-15 mcg, which course is a lot more than what we'd get from taking 25 or 50 mcg, but the question is if we want it - or need it.

Very few plants have been tested for B12, the test procedures are highly questionable, and it's difficult both to detect low (but still useful) B12 levels and to distinguish between active, bio-available B12 and 'passive' B12 analogues. Still, there are many plants that may contain small amounts of B12, and having the controversy about taking too much B12, many, extremely small portions of B12 definitely seems like the way to go - and also seems to be natural way.

[chickendude]

How can I get my blood checked for B12 (and other vitamins/minerals)? Do I just go to my doctor?

The thought of blood and veins and such makes me feel pretty nauseated, so how much blood do they need?

[chickendude]

Also, where does the B12 from supplements come from? Is it synthetic?

[Korn]

How can I get my blood checked for B12 (and other vitamins/minerals)? Do I just go to my doctor?

Yes.

The thought of blood and veins and such makes me feel pretty nauseated, so how much blood do they need?

Not much...

[Korn]

Also, where does the B12 from supplements come from? Is it synthetic?

Many people wonder where this vitamin comes from. One method of creating B12 for supplements is to synthesize B12 by using single-celled microbes. B12 comes from natural bacteria. B12 has also been produced by cultivating it on the surface of molasses.

[RedWellies]

so how much blood do they need?

When I last had a blood test, the Doctor only took a small syringe full of blood. It's not like when you give/donate blood (they take about a pint then I think.)

[Smoothie]

we had a very good dietist coming to tell us about vegan nutrition and stuff like that, and she said that some of the best ways to get vegetable B12 is to eat flaxoil, pumpkinseeds and dried abricots. and then to ALWAYS take some vitamins on the side. here in denmark we can't get fortified foods, since it's illegal to sell those (it's something about not wanting people to believe that the junkfood is healthy, and that fortified foods can cause cancer and the human body often isn't able to get anything out of these vitamins, so they should get them from natural sources).

[Korn]

Hi Smoothie, if you see that dietician again, please ask about that flaxoil/pumpkinseed thing again! I wonder what her/his sources are...

[Smoothie]

i don't think i will, but i've read some of her books. she's been studying vegetarianism/veganism/detoxification and healthy living for about 30 years - i totally rely on the information

[Korn]

...and if I say that there are many people who have studied veganism for 35 years, and that they say that there is no B12 in flax oil or pumpkin seeds, who would you trust then?

[Smoothie]

probably her well, anyway, it's hell delicious, so it wouldn't hurt to try?

[T-Bird]

Korn,
Do you have any information on the absorption of sublingual B12? I've been taking source naturals sublingual B12 - 5mg since I got a blood test back that had me at 100 something. Once you're deficient, how long does it take for you to build back up where you don't have to worry anymore.

Also I read somewhere that the methylcobalmin is less stable, so I worry I'm not getting as much as I think if destable-izes itself.

[eve]

In today's Health Report on abc-radio national, there was a discussion relating to a recent study over a period of 2 yrs in New Zealand. There were two cohorts, one lot ate a diet that included B vitamins and folate in plant form, the other lot took vitamin tablets of B6, B12, and Folate. At the end of 2 years the only difference in health between the two groups, was that those who ate plants were significantly better off healthwise than those who ate the vit tabs. In fact, those taking vit tabs may have been careless about eating plant foods, but certainly their homocysteine had increased.

[Korn]

Here are some more numbers re. B12 absorption rates:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2532799/table/T1/#TF1-4

1 μg	0.56 μg (56%)	0.01 μg (1.2%)
10 μg	1.6 μg (16%)	0.1 μg (1.2%)
50 μg	1.5 μg (3%)	0.6 μg (1.2%)
500 μg	9.7 μg (2%)	7.0 μg (1.3%)
1000 μg	~ 13 μg (1.3%)	~ 12 μg (1.2%)

This article from 2008 suggests that when consuming 50 mcg, only 3% of the B12 is absorbed, with an intake of 500 mcg, only 2% is absorbed, and 1.3% or ~ 13 μg B12 is absorbed when consuming 1000 mcg.

This is for people with normal absorption. Others (1-2% of the population) have much lower absorption rates (see the table).

The estimated daily requirement for people with normal absorption rate is ~ 1 μg/day.