NUTRISPEAK by Vesanto Melina MS, RD
• Vitamins are essential to life. The “vita” in their name refers to that fact. The “amin” was added in 1912 when it was mistakenly believed all vitamins contained nitrogen compounds (amines). In the relatively young science of nutrition, all of the vitamins were discovered during the last century. As research continues to accumulate regarding optimal sources and intakes, don’t be surprised by an overabundance of controversy, theories and varied recommendations.
Two vitamins that invite special attention are vitamins B12 and D. This column is devoted to vitamin B12. In next month’s column, vitamin D will be spotlighted.
Roles and sources
Vitamin B12 performs dozens of functions in the body. Its two primary roles are: 1) The development and maturation of red blood cells. 2) The proper functioning of the nervous system, including formation of the myelin sheaths around nerves. Vitamin B12 is present in animal products (originating from bacterial contamination), in fortified plant foods (with B12 of bacterial origin) and in supplement form. This vitamin comes from bacteria and a few other one-celled organisms. A form of B12 can be found in meat, fish and poultry due to bacterial contamination, but B12 is not present in unfortified plant foods. Therefore, people with plant-based diets need a reliable source, specifically the forms present in supplements and fortified foods.
Who needs B12 supplements?
Firstly, it is recommended that everyone above 50 years of age get B12 in the form of supplements or fortified foods. With age, changes occur along the gastrointestinal tract meaning that approximately one in three people loses the capacity to absorb the protein-bound form of B12 from animal products. In contrast, the B12 in supplements and fortified foods is well absorbed by these seniors. A small proportion of people further lose absorptive capacity and need monthly vitamin B12 injections. Secondly, B12 from supplements or fortified foods is essential for everyone on a plant-based – or mainly plant-based – diet.
How much, how often, what type?
Getting enough B12 involves following one of the recommendations below:
- Two or three times a week, take 1000 mcg (micrograms) of vitamin B12 (cyanocobalamin).
- Or take a daily supplement that provides at least 25 mcg. It may be beneficial for seniors above age 65 to take 500 mcg daily. Excess is simply excreted.
- Or take two or three servings daily of B-12 fortified foods. Examples include fortified nutritional yeast and veggie “meats,” cereals and non-dairy milks that have been fortified with B12 (check labels).
This vitamin has two active forms when in the body: methylcobalamin, which is involved in the building of red blood cells and adenosylcobalamin, which is required for formation of the myelin sheaths around nerves. As it turns out, neither methylcobalamin nor adenosylcobalamin can perform both functions. You may use a combination of the two, however, little research has been done to determine requirements. Your best bet is to take cyanocobalamin, the stable form used in supplements and fortified foods.
For more on vitamins – and amounts at different ages and stages – see Becoming Vegan: Comprehensive Edition (for health professionals and nutrition enthusiasts) and Becoming Vegan: Express Edition, award-winning books by Davis and Melina. For more information about Vesanto Melina, 604-882-6782 www.becomingvegan.cawww.camd58.sg-host.com