From The October 2000 Issue of Nutrition Science News
Boston, Mass.— After testing 3,000 men and women (ages 26 to 83) living in Framingham, Mass., researchers from the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, located here, discovered that 39 percent were suffering from "low normal" levels of vitamin B12—below 258 pmol/L. Although these values are well above the currently accepted deficiency level of 148 pmol/L, it has been shown that even at this low normal level, people often exhibit deficiency symptoms, such as balance disturbances or confusion.
Extrapolated to the U.S. population, up to two-fifths of the country could be suffering from marginal vitamin B12 status, and this figure could be actually higher since extra folic acid will mask B12 definciency. The good news is that most people can improve their B12 status through supplementation.