Everybody asks vegetarians how we get our iron, or how we get enough protein, and those are certainly important. But we can’t forget about another totally important player for any vegetarian – B12. So this month we’re getting down and detailed about B12.
Vitamin B12 is one of eight B-vitamins. It’s a water-soluble vitamin, which exists in several forms and it contains the mineral cobalt.
Important stuff! Vitamin B12 plays a vital role in the normal functioning of the brain and nervous system, as well as cell metabolism, fatty acid metabolism, amino acid metabolism, and the synthesis and regulation of DNA.
Get this – no plants, fungi, or animals are capable of producing this vitamin. All B12 is produced by certain strains of bacteria that have the enzymes required for its synthesis. For example, algae are believed to acquire B12 through a symbiotic relationship with heterotrophic bacteria in which the bacteria supply B12 in exchange for fixed carbon from the algae.
B12 can be produced industrially through bacterial fermentation synthesis – this is where most of the B12 in supplements or fortified foods comes from.
Vitamin B12 is found in most animal foods, including meat, fish, poultry, eggs, and milk products; the amount and quality of the B12 depends on the diet of the animal.
Other than some fermented foods, there are very few non-animal food sources of biologically active B12. Many vegan foods are fortified with vitamin B12, including non-dairy milks, breads, cereals, meat substitutes, and some types of nutritional yeast. It is important to note that not all nutritional yeast contains B12. It must be fortified, so if you’re relying on nutritional yeast for your B12, check the label carefully.
To make matters concerning B12 and plant-based foods a bit more complicated, there is a group of biologically inactive B12-like analogues referred to as pseudovitamin-B12. These are found alongside B12 in humans and in many food sources. In most cynobacteria, including Spirulina, pseudovitamin-B12 is predominant. Pseudo B12 can make it difficult to test for B12 deficiency, as it can imitate true biologically active B12 in blood tests.
Recommendations vary from country to country. The US recommended daily average (RDA) for adults is 2.4 µg (micrograms) of vitamin B12/day. This bumps up to 2.6 µg during pregnancy, and 2.8 during lactation and breastfeeding. Since B12 is a water-soluble vitamin, toxicity doesn’t seem to be a problem; what the body doesn’t need is simply excreted in our urine.
Very low B12 intakes can cause anemia (this is not the same as iron deficiency anemia) and can potentially cause severe damage, especially to the brain and nervous system. Heart disease and pregnancy complications are also of concern with B12 deficiency.
Typical B12 deficiency symptoms include low energy, tingling, numbness, reduced sensitivity to pain, blurred vision and a sore tongue.
Our livers are able to store several years worth of vitamin B12, so deficiency symptoms may not appear for 5 years or more. This is important for long-term vegetarians and vegans, who should be tested for B12 deficiency, especially if following a diet that doesn’t include eggs or dairy. Vegans eating a macrobiotic or raw diet that avoids fortified foods are at an especially high risk.
Adults over 50 may not meet the RDA without supplementation, regardless of diet. And individuals with digestive system disorders such as Crohn’s disease, celiac disease or IBS may not be able to absorb enough B12 from food to maintain healthy body stores and require supplementation as well.
The only way to know for sure if you’re lacking B12 is to see your doctor about getting a blood test. Blood homocystine levels may provide a more accurate measurement for those following a vegan diet, as opposed to blood B12 or blood counts.
If you’re following a strict vegan diet, pay attention. The only reliable vegan sources of B12 are fortified foods such as non-dairy milks, breads, cereals, and fake “meat” products. But not all of these products are fortified and not all are fortified equally, so you should get to know your labels.
If you’re following a vegan diet you should either eat B12 fortified foods that add up to at least 2.4 µg/day OR take a daily B12 supplement. If you’re going the supplementation route, it’s important to know that the body’s ability to absorb B12 from supplements is limited – aim for a supplement with around 10 µg or more.
B12 is important stuff! If you’re in an at-risk group for deficiency, get yourself tested. If you’re vegan, read labels and understand which foods you’re eating are fortified and how that adds up, and/or consider a daily B12 supplement. If you’re vegetarian and are pregnant or are considering becoming pregnant, talk to your doctor about whether or not you need a B12 supplement.
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