When It Comes to Vitamins, More Is Not AlwaysBetter

Researchers funded by theAgricultural Research Service (ARS)looked into links between dietary intakes of two B vitamins—folate andvitamin B12—and mental agility among seniors. Folate and B12 are importantnutrients for the development of healthy nerves and blood cells. ARS is theU.S. Department of Agriculture's chiefscientific research agency.

The study, published in 2007, was led by epidemiologist Martha Morris andcolleagues at the ARS Jean Mayer USDA Human Nutrition Research Center on Aging(HNRCA)in Boston, Mass. It was based on an analysis of data collected from the U.S.population for the National Healthand Nutrition Examination Survey between 1999 and 2002. Blood tests wereused to determine the volunteers' folate and vitamin B12 levels.

U.S.-enriched cereal grain products have been fortified with the syntheticform of folate (folic acid) since 1998. The HNRCA'sPaulJacques andJacobSelhub, coauthors on the 2007 study, had previously published papers withSilvina Choumenkovitch, reporting that folate levels have become extremely highin the U.S. population since fortification began.

The researchers found an interesting association among seniors aged 60 andolder whose vitamin B12 blood levels were low. Aging and taking stomach-acidblockers can contribute to a gradual lessening of B12 absorption in the body.

People with high folate and low B12 status were found to be at adisadvantage when compared to those with normal folate and low B12 status; theformer group was more likely to exhibit both anemia and cognitive impairment,according to Jacques. A single cognitive function test was used to assessaptitudes such as response speed, sustained attention, visual-spatial skills,associative learning and memory.

Scientists have long known that being seriously deficient in vitamin B12leads to impaired cognitive function caused by neurological complications. Theresearchers recommend future studies that look into the implications of havingtoo much folic acid, due to fortification, and too little vitamin B12, due topoor absorption.

Readmore about this research in the November/December 2007 issue ofAgricultural Research magazine.