What is Vitamin B12
All Vitamin B12 is made from bacteria living in the digestive tracts of animals. It is not found in plant foods. It may seem as if we could just use what these bacteria produce, but they are too far down in the intestines to be of any use to us. We absorb vitamin B12 in our small intestine; while the bacteria producing it live in our large intestine.
Vitamin B12 is needed for cell division and formation of healthy red blood cells. It is also needed to produce myelin, the protective sheath under the nerve fibers. Overt vitamin B12 deficiency can produce a condition called macrocytic or megaloblastic anemia, in which red blood cells don’t divide and reproduce normally. Vitamin B12 deficiency symptoms also include in nerve damage. However, because vitamin B12 is also involved in metabolism of fat and protein, a marginal intake may increase the risk for certain chronic conditions like heart disease.
There are also molecules that are very similar to vitamin B12 but that have no true vitamin activity for humans. These are inactive vitamin B12 analogues. Most methods for measuring vitamin Bl2 in foods don’t differentiate between true vitamin B12 and the inactive analogues. This has been a source of confusion for a long time. Some of the more popular sources of vitamin B12 can be found in foods like fermented soy products, tofu, sourdough bread, and some sea vegetables. There is a double risk associated with depending on these foods for vitamin B12 because of high levels of the inactive analogues, which can actually block the activity of true vitamin B12.
Plants have no need for vitamin B12, which is why they usually don’t contain any. Occasionally, a plant food might be “contaminated” with an inactive vitamin B12 analogue. That is, it contains vitamin B12 by accident. For example, one of the ingredients used to make tempeh, which is a fermented soy food, might accidentally contain vitamin B12 producing bacteria. Seaweed often pick up the bacteria that produce vitamin B12 analogues. There is some evidence that sea vegetables such as chlorella, dulse, and nori contain vitamin B12 but again, these haven’t been shown to be reliable and significant sources of the active vitamin.
Most humans get vitamin B12 by eating animal products. Animals such as cows and other true herbivores are able to absorb the vitamin B12 produced in their intestines by bacteria. Other members of the animal kingdom, including many primate species, eat at least small amounts of animal products (including insects) or feces, which can be a good source of vitamin B12.
Humans evolved to get by on pretty low intakes of vitamin Bl2. We have a rather complex physiological way of recycling it, and we also can store relatively large amounts in our livers sometimes enough to prevent overt deficiency for as long as three years. As a result, some vegan advocates insist that no one needs to worry about vitamin B12 until they have been vegan for several years and that we can get by with taking supplements just “once in a while.” This approach could be a dangerous one for a couple of reasons.
First, not everyone has optimum vitamin B12 level for three years. It depends on what your diet has been like over time and your body’s ability to absorb the active vitamin. Building up generous vitamin B12 stores can take many years of consuming the vitamin in quantities that exceed daily needs. If you have been eating a mostly plant-based or vegetarian diet before becoming vegan (that is, a diet that is more moderate in animal foods than what most Americans eat) your vitamin B12 levels may be relatively low. Some people may find themselves running through their vitamin B12 supply in just a few months. In addition, vitamin B12 levels may not be sufficient to prevent mild or marginal-type deficiencies.
Overt deficiency of vitamin B12 occurs when the levels The megaloblastic anemia that occurs with vitamin B12 deficiency is reversible with vitamin B12 therapy. Sometimes vitamin B12 deficiency anemia is “masked” by the vitamin folic acid (also called folate), which can step in and do vitamin B12’s job. Therefore one can be deficient in vitamin B12 but not have anemia if the individual’s diet is high in folate.
This may sound like a good thing, but it’s not since folic acid won’t prevent the nerve damage that can occur with vitamin B12 deficiency. If vitamin B12 intake is low and folate intake is high, the vitamin B12 deficiency can go unnoticed until it progresses to a more advanced stage. It’s an important issue for vegans since they typically have a high intake of folate, which is found-in leafy greens, oranges, and beans.’
The neurological damage that can result from a vitamin B12 deficiency typically begins with tingling in the hands and feet and can progress to far more serious symptoms. Often the vitamin B12 deficiency symptoms can be reversed, but some neurological damage can be permanent. This is especially true in babies born to mothers who don’t have adequate vitamin B12 intake during pregnancy.
The anemia and neurological symptoms associated with overt vitamin B12 deficiency are fairly obvious. But a second type of “mild” deficiency doesn’t have acute symptoms. It does its damage over time, often decades and it is only detected through medical tests. When vitamin B12 levels in the blood start to drop, the levels of an amino acid called homocysteine begin to rise. Homocysteine may damage blood vessels and nervous tissue and many studies have linked high levels to an increased risk for heart disease, stroke, and early death. Elevated homocysteine may also be related to Alzheimer’s disease and neural tube defects in the developing embryo.
Research shows that vegans and vegetarians who supplement with vitamin B12 have healthy levels of homocysteine. Those who don’t take supplements have high homocysteine levels.” These findings present strong evidence that vegans who don’t use supplements and who insist that they feel fine-may be damaging their health over the long term. (Folate and vitamin B6 also affect the vitamin homocysteine, but most vegans get plenty of those.)
While this might sound like vitamin B12 is a big problem for vegans, it’s an issue that is so easily resolved that it should not be a concern. In fact, it is a concern only when vegans do not obtain good advice about vitamin Bl2 or don’t want to use supplements or fortified foods.
Vegans actually have the advantage when it comes to vitamin B12. As people age, no matter what type of diet they follow, their ability to absorb vitamin B12 found naturally in foods begins to decline. Vitamin B12 in animal foods is bound to protein, and the decline in stomach acid that tends to occur in older people makes it harder to absorb vitamin B12 from the protein. Since the vitamin B12 found in supplements and fortified foods are not bound to protein, they are more easily absorbed by older people. Many older people may follow this, but vegans who are paying attention to good nutrition are already using vitamin B12 supplements or fortified foods.
There are a few important points to keep in mind about supplementing with vitamin B12.
- First, vitamin B12 supplements should be either chewable or sublingual (dissolving under the tongue) since research shows that, in some people, vitamin B12 isn’t well absorbed from pills that are swallowed whole.
- Also, the body is used to getting little bits of vitamin B12 here and there throughout the day. When confronted with a big dose of the vitamin it absorbs just a tiny fraction of the whole amount. So when you take vitamin B12 infrequently, you need rather large amounts in order to absorb enough. The RDA for vitamin B12 is just 2.4 micrograms for adults. But if you are getting your daily dose from a supplement, you may need as much as 25 to 100 micrograms. If you use vitamin D supplement just two or three times a week, you may need 1,000 micrograms each time.
- All vegans and vegetarians need to take a vitamin BI2 supplement or consume foods that are fortified with this nutrient. Plant foods are reliable sources of active vitamin B12 only if they are fortified with the vitamin. On food labels, the Daily Value for vitamin Bl2 is 6 micrograms. So if a product provides 25 percent of the Daily Value, it contains 1.5 micrograms.
- Nutritional yeast is a popular choice with many vegans. Its cheesy flavor is great when mixed into bean and grain dishes or sprinkled over popcorn. Nutritional yeast is grown on a nutrient-rich culture and contains only the nutrients that are in that culture. Therefore it is unsafe to assume that every type of nutritional yeast is a good source of vitamin B12.
- If you rely on fortified food sources of vitamin B12 it is best to have at least two fortified food sources on hand in case a particular batch of a foods containing vitamin B12 that is somehow damaged. Do not rely solely on one type of fortified food.
- Approximately 2 percent of older individuals are unable to absorb vitamin B12. This disease is called pernicious anemia. This disease is known to be irrelevant to the vegan life style, however if you are supplementing regularly with vitamin B12 and still suspect that you have symptoms of vitamin Bl2 deficiency, such as extreme fatigue or neurological problems, then it is best to get your vitamin B12 levels tested. Pernicious anemia is treated with vitamin BI2 injections.
Taking a daily vitamin B12 supplement is a small thing that can make all the difference in achieving ultimate health for a vegan. Based on the wealth of information available, the vitamin B12 sources, requirements and supplementation is not a subject for debate. Vitamin B12 supplements or fortified foods are an essential part of a well-balanced and responsible vegan diet at all stages of the life cycle.