While this is well above the currently accepted deficiency level of 148 pmol/L, some people exhibit neurological symptoms at the upper level of the deficiency range, explains study leader Katherine L. Tucker. She is a nutritional epidemiologist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston.
"I think there’s a lot of undetected vitamin B12 deficiency out there," says Tucker. She noted that nearly 9 percent of the study population fell below the current deficiency level. And more than 16 percent fell below 185 pmol/L. "Many people may be deficient at this level," she says. "There is some question as to what the clinical cutoff for deficiency should be."
Deficiency can cause a type of anemia marked by fewer but larger red blood cells. It can also cause walking and balance disturbances, a loss of vibration sensation, confusion, and, in advanced cases, dementia. The body requires B12 to make the protective coating surrounding the nerves. So inadequate B12 can expose nerves to damage.
Tucker and colleagues wanted to get a sense of B12 levels spanning the adult population because most previous studies have focused on the elderly. That age group was thought to be at higher risk for deficiency. The researchers also expected to find some connection between dietary intake and plasma levels, even though other studies found no association.
Some of the results were surprising. The youngest group—the 26 to 49 year olds—had about the same B12 status as the oldest group—65 and up. "We thought that low concentrations of B12 would increase with age," says Tucker. "But we saw a high prevalence of low B12 even among the youngest group."
Bookmarks