Spirulina is Not a Good Source of Vitamin B12 for Vegans
Vitamin B12, also known as cobalamin, is necessary for the production of red blood cells and plays an important role in maintaining a healthy nervous system. A member of the B-complex group of vitamins, this essential nutrient is naturally found in animal products including fish, meat, poultry, eggs and dairy products. You may have also heard claims that certain seaweeds and algae, such as spirulina, are good sources of vitamin B12; however, on the basis of current evidence, these claims seem unsubstantiated and spirulina cannot be considered a reliable dietary source of vitamin B12 for vegans and other people who may not be getting enough of this essential nutrient through their diets.
Spirulina Algae Contains Inactive Pseudovitamin B12
The claim that spirulina is a good dietary source of vitamin B12 for vegans appears to be nothing but a myth. While spirulina does contain a high amount of pseudovitamin B12, your body won't be able to use it the same way it uses real vitamin B12 because this B12-like analogue is biologically inactive in humans.
An in-vitro study published in the European Journal of Biochemistry demonstrated that the binding affinity of pseudovitamin B12 to intrinsic factor, a protein required for the absorption of vitamin B12 in mammals, is 500 times lower than for true vitamin B12.
In another study, published in The American Journal of Clinical Nutrition in 1991, macrobiotic vegan and non-vegan toddlers suffering from anemia caused by a vitamin B12 deficiency were given spirulina and nori, along with a few other sources of vitamin B12 analogues. Supplementation with spirulina and nori did not seem to improve the toddlers' condition; in fact, after 4 to 6 months, their anemia had gotten worse.
So What Are Good Sources of Vitamin B12 for Vegans?
At present, most experts agree that only B12 fortified foods and B12 supplements can be considered reliable sources of B12 for vegans. Even though there is some evidence that certain seaweeds (other than spirulina) contain the type of vitamin B12 that is bioavailable in humans, there is no hard evidence proving that eating these seaweeds can actually prevent or cure anemia caused by a vitamin B12 deficiency in vegans. Vegetarians, on the other hand, may be able to get enough vitamin B12 without fortified foods and B12 supplements as eggs and dairy products such as milk contain decent amounts of this vital nutrient.
1. F. Watanabe et al (2002). Characterization and Bioavailability of vitamin B12-Compounds from Edible Algae. Journal of Nutritional Science and Vitaminology, vol. 48, no. 5, pages 325-331.
2. Stupperich, E. and Nexo, E. (1991) Effect of the cobalt-N coordination on the cobamide recognition by the human vitamin B12 binding proteins intrinsic factor, trans-cobalamin and haptocorrin. European Journal of Biochemistry, 199, 299-303.
3. Dagnelie PC, van Staveren WA, van den Berg H (1991). Vitamin B-12 from algae appears not to be bioavailable. American Journal of Clinical Nutrition.
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