|
|
The Age of Folate Fortification
Folate is one of the B vitamins that affect the balance of homocysteine levels. A link between high blood folate levels and relatively lower homocysteine levels has long been known.
Since 1998, all U.S. enriched cereal grain products, such as bread, pasta, flour, breakfast cereal, and rice, have been required to be fortified with folic acid—the synthetic form of folate—to help prevent certain birth defects.
Since fortification began, not only have folate deficiency and birth defects decreased, but so has the prevalence of high homocysteine levels, according to Rosenberg and colleagues. High homocysteine levels are associated with an increased risk of developing heart disease, stroke, dementia, and Alzheimer’s disease.
“It is possible that this drop in the population’s homocysteine concentrations may also bring about a lower incidence of these diseases,” says Troen. “But whether this will be the case is not yet certain. And though there are clear benefits of increasing the population’s folic acid intake as a whole, new research suggests that there may be a downside for some individuals.”
B Vitamins and Brain Power
Epidemiologists Paul Jacques and Martha Morris, biochemist Jacob Selhub, and Rosenberg recently completed a study of the interrelationships among the B vitamins and cognitive function in this age of folate fortification. B vitamins are involved in the synthesis of chemicals crucial to brain function. Scientists have long known that being seriously deficient in vitamin B12 leads to impaired cognitive function due to neurological complications. The researchers used a combination of blood markers to classify subjects’ vitamin B12 ranking.
Morris, who led the study, found that among people aged 60 and older, those with high blood levels of folate and normal, or adequate, vitamin B12 status scored high on cognitive function tests. These seniors were given a test that required response speed, in addition to attentiveness, visual-spatial skills, associative learning, and memory.
But what about those who had low vitamin B12 blood levels—a status that is common among seniors due to the poorer gastrointestinal conditions that come with aging? Low vitamin B12 status was linked with lower scores on cognitive tests.
“The people with high folate and low B12 status were more likely to exhibit both cognitive impairment and anemia than those with normal folate and low B12 status,” says Jacques.
The researchers recommend that future studies examine the implications of having high folate status due to fortification and too little vitamin B12 due to aging.
What’s in a NAME?
Population researcher Katherine L. Tucker is focusing on vitamins and cognition in a series of community-based studies. In the Normative Aging Study, a longitudinal study of originally healthy men in the Boston area, she and colleagues found that those with the best B-vitamin status at the start, or baseline, had little change in their cognitive-function test scores. But test scores went down significantly in the men with the lowest baseline B-vitamin status and highest homocysteine concentrations.
Rosenberg and Tucker are also working with another high-risk group: homebound elderly. “The Nutrition, Aging, and Memory in Elders, or NAME, study is designed to look at the relationships among levels of several nutrients and subsequent cognitive function,” says Tucker.
“We are studying folate, vitamin B6, vitamin B12, vitamin C, and vitamin E intakes among this population, along with each individual’s cognitive functioning,” she says. The data generated may be useful in developing dietary strategies and supplementation targets to help the elderly maintain their cognitive function.
These and future studies are essential to determining whether—and to what extent—nutritional factors can be used to prevent cognitive impairment as we age.—By Rosalie Marion Bliss, Agricultural Research Service Information Staff.
This research is part of Human Nutrition, an ARS national program (#107) described on the World Wide Web at www.nps.ars.usda.gov.
To reach scientists mentioned in this article, contact