When It Comes to Vitamins, More Is Not Always
Better
By Rosalie Marion
Bliss
November 16, 2007
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Based on a population study, seniors with normal
folate levels fared better than those with high folate levels under certain
conditions. In photo, epidemiologist Martha Morris and biochemist Jacob Selhub
examine apparent associations between B vitamin status and cognitive test
results. Click the image for more information about it.
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Researchers funded by the
Agricultural Research Service (ARS)
looked into links between dietary intakes of two B vitamins—folate and
vitamin B12—and mental agility among seniors. Folate and B12 are important
nutrients for the development of healthy nerves and blood cells. ARS is the
U.S. Department of Agriculture's chief
scientific research agency.
The study, published in 2007, was led by epidemiologist Martha Morris and
colleagues 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 Health
and Nutrition Examination Survey between 1999 and 2002. Blood tests were
used to determine the volunteers' folate and vitamin B12 levels.
U.S.-enriched cereal grain products have been fortified with the synthetic
form of folate (folic acid) since 1998. The HNRCA's
Paul
Jacques and
Jacob
Selhub, coauthors on the 2007 study, had previously published papers with
Silvina Choumenkovitch, reporting that folate levels have become extremely high
in the U.S. population since fortification began.
The researchers found an interesting association among seniors aged 60 and
older whose vitamin B12 blood levels were low. Aging and taking stomach-acid
blockers 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 a
disadvantage when compared to those with normal folate and low B12 status; the
former group was more likely to exhibit both anemia and cognitive impairment,
according to Jacques. A single cognitive function test was used to assess
aptitudes such as response speed, sustained attention, visual-spatial skills,
associative learning and memory.
Scientists have long known that being seriously deficient in vitamin B12
leads to impaired cognitive function caused by neurological complications. The
researchers recommend future studies that look into the implications of having
too much folic acid, due to fortification, and too little vitamin B12, due to
poor absorption.
Source: USDA , Agricultrual Research Service.
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