BOSTON (October 12, 2016)—Consuming too much folate (vitamin B9) is associated with increased risk for a nerve-damage disorder in older adults who have a common genetic variant. Although variable by race or ethnic background, an estimated one in six people in the U.S. carry two copies of a genetic variation in TCN2, a gene that codes for a vitamin B12 transport protein. For some of these individuals, the TCN2 variation (referred to as GG) can lead to conditions related to vitamin B12 deficiency even if they consume normal amounts of B12.
In an epidemiological study involving 171 adults aged 60 and older, a team led by scientists from the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts (USDA HNRCA) found that individuals with the GG variant of TCN2 were three times more likely to have peripheral neuropathy—nerve damage commonly associated with vitamin B12 deficiency—when compared to individuals without the variant.
Among study subjects who consumed more than twice the Recommended Dietary Allowance (RDA) of 800 micrograms per day of folate, individuals with the GG variant had seven-fold higher odds for peripheral neuropathy compared to those without. The team found no significant difference in odds among individuals who consumed less than 800 micrograms of folate a day.
The findings were published in the American Journal of Clinical Nutrition on Oct. 12.