VITAMIN B12
Given the high vegetable intake in most plant-based diets, some vegans may mistakenly believe that vitamins are not a concern for them. While it is true that many vitamins are abundant in healthy plant-based diets, there are a few that require special attention, B12 being one of them.
Vegans who do not carefully supplement their diets with B12 are at a high risk for deficiency. The symptoms of deficiency may appear early on or they may not be obvious until many years down the road when the B12 stores have been depleted. Insufficient B12 consumption and/or absorption results in abnormally shaped, large blood cells. These cells are not able to carry oxygen throughout the body, leading to an anaemic state. B12 is also responsible for the maintenance of protective sheaths that surround nerve fibers. Neurological damage occurs when these sheaths are not properly maintained. This is displayed through symptoms such as confusion, depression, irritability, inability to concentrate, tingling and numbness in the extremities, muscle fatigue, apathy and possibly eventual paralysis or dementia. Damage can be sudden and, in some cases, irreversible.
Where do I get it?
Vitamin B12 is produced by bacteria. By taking sufficient supplements or consuming fortified foods, vegans can ensure a healthy level of B12. People who eat animal flesh are able to obtain the bacterial B12 within the animal products. Various myths abound about ‘natural’ vegan sources of B12.
B12 myths
Some proclaim that there are enough bacteria on garden vegetables that, if eaten unwashed and raw, a vegan can absorb sufficient B12. This may have held true at some point in history; however, with our present day nutrient-robbed, sterilized soils and highly processed foods, bacteria growing on vegetables is an unreliable source. The bacteria would not be found in the vegetables themselves, but rather on the dirt left on the vegetables. Very few people like to eat dirt in their garden salad. Some raw foodists believe that are able to consume all their nutrients from fresh, raw food. Given the difficulty in ascertaining B12 from vegetables now, raw foodists may want to consider taking a B12 supplement.
Other proclaimed sources of B12 which are not to be relied on are: fermented soy foods (e.g., tempeh, miso), ‘green’ foods (e.g., algae, spirulina, alfalfa), nuts, legumes, and sea vegetables (e.g., arame, wasake, kombu, nori). While it is likely that fermentation of soy may add some B12, the levels can vary greatly and cannot be depended on. Some of the B12 reported to be in the above mentioned foods are actually an analog form, meaning that they appear similar to the actual vitamin but are not usable by humans and, in fact, may even inhibit real B12 absorption.
So, yes, it is possible to find B12 from actual plant-based food sources; however, the levels are not quantifiable and it is, therefore, safer to use supplements and enriched foods where you can determine exactly what your intake is.
How much is enough?
If you are relying on fortified foods for your B12, be sure to read the ‘Nutritional Value’ label and calculate your intake accordingly. For example, to get the 3 micrograms (mcg) of B12 required daily, you need to be drinking 2 cups of B12 fortified soymilk each day. Because B12 can only be absorbed in small quantities, supplements must be spread out throughout the week rather than consumed in one large dose. If you have been taking a high potency weekly pill, you may want to consider breaking the pill in half to spread out your intake. On the other hand, there is a more extreme school of thought which suggests taking a 'super-dose' once a week and this should be a 2000 mcg sub-lingual (under the tongue) tablet. Given that these two schools of thought are quite opposing, you may wish to do further research on this and make your own decision.
The minimum amount of B12 required to prevent deficiency is 2.4 mcg per day. During pregnancy that amount increases to 2.6 mcg and during lactation a mother needs at least 2.8 mcg. These amounts are just to prevent deficiency. Because excess B12 is excreted by the body, higher intakes (though not excessive) can insure a proper supply is maintained within the body.