However, the group of European researchers found that, in order to correct a deficiency, oral doses need to contain more than 200 times the recommended daily allowance (RDA) of Vitamin B12.
Study author Dr. Lisette C. P. G. M. de Groot of Wageningen University in the Netherlands explained that most people develop vitamin B12 deficiencies as a result of “malabsorption,” in which their bodies become unable to extract vitamin B12 from food.
The deficiency typically strikes older people, she added, and takes years to develop. In some instances, people who avoid animal products - such as vegans and followers of a macrobiotic diet - can also develop a deficiency in vitamin B12 as a result of not eating enough B12-rich foods, de Groot noted.
A vitamin B12 deficiency is typically treated by monthly, often painful, shots, de Groot and her colleagues, including Simone J. P. M. Eussen, report in the Archives of Internal Medicine.
Despite the massive doses needed, oral medicine has the advantage of being easy to administer and painless, said de Groot. No side effects have been reported, she added.
SOURCE: Archives of Internal Medicine, May 23, 2005.
Revision date: June 14, 2011
Last revised: by Sebastian Scheller, MD, ScD