Tuesday, May 17, 2011

The Big One - B12

Overall a vegan diet is very healthy and can lead to reduced risk of heart disease.   However a "lazy" vegan diet can lead to specific nutritional deficiencies.  By far the biggest nutritional issue for vegans is B12.  B12 is important!  Every cell in our bodies needs B12 and you cannot live without it. 

Our daily requirement for B12 is 2-3 micrograms.  That doesn't sound like a lot, right?  But the problem is that humans, and all other animals, cannot produce B12. 

So where does the B12 in animal products come from?  It is either produced by helpful bacteria in the animal's gut, or they get it from eating other animals.

Plants also cannot produce B12.  Plant food does not have any B12.  It is possible that you can get some B12 from eating unwashed vegetables due to the dirt and bacteria on the skins.  But an exclusively vegan diet does not contain enough, if any, naturally occurring B12.  So vegans need to either take a B12 supplement or eat foods that are B12 fortified (ie foods that have a B12 added).

Only certain bacteria, and some algae, are able to produce B12.  The B12 in supplements comes from bacterial fermentation.  It is not artificially synthesized.  It is vegetarian and vegan friendly.

Many foods are now B12 fortified:
- most soy milks and many other non-dairy milks
- many cereals
- marmite and some other yeast spreads (but not good old Aussie Vegemite!)
To see what percentage of your daily B12 you will get from a "serve" just check the label.

But what about mushrooms?  "Meat for Vegetarians" the add calls them. That may be stretching it slightly.  Mushrooms are not a plant and yes mushrooms do contain some B12.  However you would have to eat literally bucket loads every day to meet your B12 requirements.

FAQ about Mushrooms

A typical serve of mushrooms may contain as much as 5% of your daily requirements so you would have to eat 20 serves of mushrooms every day.  Now I like mushrooms but surely no one likes them that much!

For further discussion about possible (but definitely not proven) vegan sources of B12:

But beware, some foods that are said to contain B12, like spirulina, actually may contain a pseudo-B12 molecule that can lower your metabolically active B12.  This can potentially be dangerous for vegans.

The good news is that most people have a lot of B12 stored in their body and the liver is very good at recycling B12.  So if someone switches from a traditional western diet to a strict vegan diet they probably have a starting point of 3-5 years worth of B12 in their body.  Meaning that they won't have to stress to much about B12 for a while and can focus on other issues of adjusting to their new diet.  Also people who just reduce their animal product intake (rather than being strict about it) probably do not need to worry at all.

The Take Home Messages:
1. Vegans (and some vegetarians) need adequate B12 supplementation, either from a pill or from B12 fortified foods.
2. Mushrooms can provide you with a little B12 but not enough to live on
3. If you are a vegan or vegetarian I recommend that you see your GP every 2 years or so for a blood test to check your B12 level.  While you are at it I also recommend that you get your iron and Vit D level checked too.

If you want to read more about B12 check out Vegan Health - B12

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