Vitamin B12 deficiency

[martianwarrior]

I found out that the main cause of b12 deficiency is caused by eating meat.
it seems we don't need to eat eggs and fish in order to maintain b12 stores and we don't need to secrete and thus waste as much b12(bile) when digesting fruits and mild veggies.

both meat eaters and vegans have so called low b12 stores. we place too much emphasis on this. meat eaters use and restore b12 rapidly, even viciously... while vegans and fruitarians use less and are able to maintain stores for longer assuming nothing else occurs that could disrupt b12 stores... like vomiting a lot.

http://www.youtube.com/watch?v=gaEzEaehswg

[RRM]

i found out that the main cause of b12 deficiency is caused by eating meat.

Yes, the intrinsic factor-mediated B12 absorption system is readily saturated, so that little B12 is absorbed from a single high-B12 meal. Watanabe F
But as long as you keep eating meat, its impossible to lack B12,
(excessive alcohol and bacterial overgrowth will decrease B12 absorption though, and B12 absorption also requires
normal functioning stomach, exocrine pancreas, intrinsic factor, and small bowels)
and i understand what you are saying that:

meat eaters use and restore b12 rapidly, even viciously... while vegans and fruitarians use less and are able to maintain stores for longer

Though you still need to replenish B12 occasionally.
B12 is actually a group of closely related compounds, all containing cobalt; the cobalamins.
Only bacteria (including salmonella) and algae can make B12, but animals such as humans can convert one form of B12 into another.
Humans can store about 2 to 5 mg B12. Half of that is stored in the liver.
We lose only 0.1% of this B12 by secretions (such as bile, indeed) into the gut (we cannot re-absorb all).
So that we can store enough B12 in the liver to last for years.
Not every body is equally capable in retrieving B12, so that a B12 deficiency may also occur within a year.
Children may rapidly develop a B12 deficiency though.

(BTW: Availability of B12 in cooked / fried / scrambled eggs seems to be only <9% Watanabe F , but when the pH and pepsin activty is right,
B12 is readily transferred from egg yolk cobalamin-binding protein to human saliva (39%-58% transfer) Del Corral A et al )

[martianwarrior]

it seems that we do basically agree about b12. let me clear up my point on the issue...
more and more evidence is pointing towards fermented foods as being a good b12 source...
i can see that you feel the wai diet is the middle of the road as far as not forcing b12 while still getting some on a regular basis.
i suppose i am simply curious as to whether or not it is even necessary to maintain a specific amount of b12 in the body.

[RRM]

more and more evidence is pointing towards fermented foods as being a good b12 source

Only bacteria and algae can produce B12, so that one may obtain B12 through fermentation of specific microorganisms.
Nori seems to be a good source Miyamoto E et al, though conversion of cyanocobalamin to methylcobalamin may be very poor.

i am simply curious as to whether or not it is even necessary to maintain a specific amount of b12 in the body.

Yes, we do need B12.
There is no question about that, as it is required for normal cell metabolism, involved in DNA synthesis and fatty acid synthesis and energy production,
though much of its functions can also be performed by vitamin B9 (folic acid).
Yet, even when B9 is abundantly present, a lack of B12 will make the body unable to convert methylmalonyl coenzyme A into succinyl coenzyme A.
This results in elevated levels of methylmalonic acid (MMA), which prevents normal fatty acid synthesis,
and may get incorporated into fatty acids (instead of malonic acid), and if such a fatty acid is incorporated into myelin,
the myelin will be too weak, resulting in degeneration of the central nervous system and spinal cord.
So that even when sufficient B9 is available (no anemia), a lack of B12 will cause neuropathies. Wiki
As you use B12 daily, the stores will get emptier daily, so that you need to replenish B12 regularly.

[fred]

In this article : http://www.ars.usda.gov/is/pr/2000/000802.htm : B12 Deficiency May Be More Widespread Than Thought

B12 deficiency is quiet common among vegetarians/vegans as well as omnivores. This article says that B12 is better absorbed from dairy and fortified food than from meat.

On wikipedia : http://en.wikipedia.org/wiki/Vitamin_B12_deficiency

Two causes for B12 deficiency are coeliac disease and bacterial overgrowth.

Given that I don't eat dairy nor B12 fortified food, that I have coeliac disease or something similar, that I have a bacterial overgrowth that prevent me to properly digest animal protein (gas/abdominal cramps), given that 10 year ago, after 5 years on a high fruit low animal protein diet, I was diagnosed B12 deficient (I was saved by B12 intramuscular injections), I guess I should be borderline B12 deficient and wonder if B12 supplementation would not be a good idea for me.

Measurement of methylmalonic acid seems to be the best way to diagnose B12 deficiency. Oral therapy is effective : http://www.aafp.org/afp/2003/0301/p979.html

What do you think ?

[overkees]

Egg yolk is rich in B12. You need to eat about 5 for 30-40% of your daily value. Can you eat herring? Herring is extremely rich in B12: http://nutritiondata.self.com/facts/fin ... cts/4065/2

[dime]

What do you think ?

It might be a good idea to test your levels?

[fred]

Liver and mollusks are the best source of B12 : http://nutritiondata.self.com/foods-000 ... 000-w.html

Testing B12, Methylmalonic acid and homosysteines levels seem to be the best thing to do.

[RRM]

I think that human breast milk is a good indicator of how little B12 we actually need.

average Vitamin B12 in mcg / 100 g.

14.6 oysters
11.0 herring, baltic sea
9.9 Ox heart
9.0 mackerel
8.5 herring
5.0 Beef, muscles only
4.2 tuna, blue fin
2.9 salmon, atlantic
2.0 Egg yolk
0.4 Chicken
0.05 Human breast milk
0.04 Human breast milk (transitional; 6-10th day post partum)

Of course, keep in mind that breastmilk is designed to be the sole source of B12, not having to compensate for foods containing no B12, such as fruits.
Adults consuming also fruits/juices, one needs to consume (high B12) animal food to compensate for the lack of B12 in fruits/juices.
For example:
100% human milk = 0.05 mcg B12 on average (per 100 g),
and 3 L of OJ (97%) plus 100 g. egg yolk (3%) is 0.06 mcg B12 on average (per 100 g combined).

Related to energy:
2.2 mcg B12 / 3000 kcal in human breast milk
2.0 mcg B12 / 3000 kcal in OJ (5.6L) + egg yolk (100g)

[fred]

I guess the information that meat eater uses up more B12 was wrong ?

[RRM]

Yes, but it is true that with high meat consumption, relatively more B12 is wasted (as little is absorbed).
You could also look at it this way: because we need so little B12, little is absorbed, even when consuming very much meat.

[Kasper]

I don't understand how vitamin B12 deficiency can occur if we only need so little.

I don't know anything about this, except that I once saw in a documentary that old people often have vitamin B12 deficiency and that it is very dangerous and can lead to chronic problems.

[RRM]

I don't understand how vitamin B12 deficiency can occur if we only need so little.

I think its because even at levels that are only slightly lower than normal, a range of (deficiency) symptoms may occur, such as such as fatigue, depression, and poor memory.
Also, even at adequate B12 intakes, there may be lack of production of intrinsic factor (due to intestinal disorders, low stomach acidity), leading to B12 malabsorption, and eventually B12 deficiency.

I once saw in a documentary that old people often have vitamin B12 deficiency

Yes, usually due to B12 malabsorption. Johnson MA
Thats because 10% Hurwitz to 31% Krasinsky of elderly have Atrophic gastritis, associated with low stomach acidity and B12 malabsorption.

[fred]

Are you sure breastmilk is the sole source of B12 for infants ?
B12 is also present in stool, dirt and bugs, and children like to play with them...

this statement is also wrong : "vegans and fruitarians use less [B12] and are able to maintain stores for longer".
(I was just surprised that you didn't correct these incorrect statements)

[RRM]

Are you sure breastmilk is the sole source of B12 for infants ?

If exclusively breasfed, yes...
Stool, dirt and bugs do not represent a significant fraction of their diet.

this statement is also wrong : "vegans and fruitarians use less [B12] and are able to maintain stores for longer".

Maybe not.
Vegetarians /vegans tend to eat a lot of beans, peas, lentils, leafy veggies (eg spinach, lettuce etc),
which are relatively high in folic acid (B9). B9 may partially replace B12, reducing the use of B12. (in the body B12 is used to regenerate B9)