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Vitamin B Rich Folates Significantly Reduce
Alzheimer’s Disease Risk
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Leafy greens, dried beans
and peas, fortified cereals and grain products, and some fruits
and vegetables are rich sources of folate. |
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Beats antioxidants, like vitamin E, and other
nutrients for health of aging brain in study of senior citizens
Aug. 12, 2005- A study of senior citizens says
those who eat the daily recommended allowance of folates – B vitamin
nutrients found in oranges, legumes, leafy green vegetables and folic
acid supplements – “significantly reduce” their risk of developing
Alzheimer’s disease.
The study, a long-term look at diet and brain aging
by the National Institute on Aging, also found that folates appear to
have more impact on reducing Alzheimer's risk than vitamin E, a noted
antioxidant, and other nutrients considered for their effect as a
brain-aging deterrent.
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Finding the Folate in Foods |
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Agricultural Research Service scientists at the Food
Composition Laboratory (FCL), in Beltsville, Maryland, have
developed a new method to analyze the essential B vitamin folate
in foods and in blood serum.
Folate piqued America's nutritional interest
when the Food and Drug Administration in 1998 required that
grain products be fortified with it. Evidence showed that risks
of birth defects would drop if mothers-to-be took more folic
acid.
Folate is important to white blood cell
makeup and for regulation of the amino acid homocysteine. Folate
is also involved in nucleic acid synthesis and methylation
reactions, both of which help the body form genetic material, or
DNA.
"Dietary folate is important for all aspects
of life—especially during growth," says Robert J. Pawlosky, the
FCL chemist who first reported the new folate analysis method
last year. "It also appears to be important for maintaining
cardiovascular tone and preventing heart disease."
Folate is a generic term used for a family
of related compounds that exhibit similar vitamin activity
within the body. The family includes folic acid, which is the
major synthetic form of folate used by food processors to
fortify foods. Each is absorbed by the body at different rates.
The new method for analyzing the amount of
folate in foods uses high-performance liquid chromatography and
mass spectrometry, or HPLC-MS. Current methods do not test for
individual folates separately. But, says Pawlosky, "With the
combination of HPLC-MS and stable isotopes, we can detect and
measure very low levels of specific folates." The lab is now
perfecting yet another way to analyze folate—HPLC with
fluorescence detection. It's a less expensive method, but one
that will complement the HPLC-MS method.
Accuracy is important to experts who
establish and reexamine the nationally recommended folate levels
and who monitor the folate fortification program. For example,
in 1989, the recommended dietary allowance was lowered from 400
micrograms (mcg) to 200 mcg for men and 180 mcg for women. Then,
in 1998, dietary folate equivalents were established—because of
differences in bioavailability, or absorption—of at least 400
mcg per day for adults.
The ARS researchers now have a memorandum of
understanding with the Nutrition Institute at the University of
Chile at Santiago. Together, they are testing food and blood
samples to gauge levels of folate and folic acid. Chile's
program is designed to compare the country's fortification
program of foods with how much they find in the Chilean
population. Pawlosky says lessons from the program's design may
eventually be used as a model for similar programs in the United
States.
FCL scientists are also working with the
National Institute of Standards and Technology (NIST) and the
Centers for Disease Control and Prevention (CDC) to coordinate
their assays of folate status in blood. The CDC monitors
nutrition status across the country, and NIST develops assays
for private technicians to use commercially in clinical labs.—By
Rosalie Marion Bliss, Agricultural Research Service
Information Staff.
This research is part of Human Nutrition, an
ARS National Program at
http://www.nps.ars.usda.gov.
Robert J. Pawlosky is with the USDA-ARS
Food Composition Laboratory
"Finding the Folate in Foods" was published
in the
December 2002 issue of Agricultural Research magazine. |
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Ultimately, 57 of the original 579 participants in
the study developed Alzheimer's disease. But the researchers found that
those with higher intake of folates, vitamin E and vitamin B6 shared
lower comparative rates of the disease. And when the three vitamins were
analyzed together, only folates were associated with a significantly
decreased risk.
In turn, no association was found between vitamin
C, carotenoids (such as beta-carotene) or vitamin B-12 intake and
decreased Alzheimer's risk.
Maria Corrada and Dr. Claudia Kawas of UC Irvine's
Institute for Brain Aging and Dementia led the effort, which analyzed
the diets of non-demented men and women age 60 and older.
"Although folates appear to be more beneficial than
other nutrients, the primary message should be that overall healthy
diets seem to have an impact on limiting Alzheimer's disease risk," said
Corrada, who like Kawas started with the study while at Johns Hopkins
University in Baltimore.
They compared the food nutrient and supplement
intake of those who later developed Alzheimer's disease to the intake of
those who did not develop the disease. It is the largest study to date
to report on the association between folate intake and Alzheimer's risk
and to analyze antioxidants and B vitamins simultaneously.
Results appear in the inaugural issue of the
quarterly peer-reviewed research journal, Alzheimer's & Dementia: The
Journal of the Alzheimer's Association.
The researchers used data from the Baltimore
Longitudinal Study of Aging to identify the relationship between dietary
factors and Alzheimer's disease risk. Between 1984 and 1991, study
volunteers provided detailed dietary diaries, which included supplement
intake and calorie amounts, for a typical seven-day period.
"The participants who had intakes at or above the
400-microgram recommended dietary allowance of folates had a 55-percent
reduction in risk of developing Alzheimer's," said Corrada, an assistant
professor of neurology. "But most people who reached that level did so
by taking folic acid supplements, which suggests that many people do not
get the recommended amounts of folates in their diets."
Folates have already been proven to reduce birth
defects, and research suggests that they are beneficial to warding off
heart disease and strokes.
Although folates are abundant in foods such as
liver, kidneys, yeast, fruits (like bananas and oranges), leafy
vegetables, whole-wheat bread, lima beans, eggs and milk, they are
often destroyed by cooking or processing. Because of their link to
reducing birth defects, folates have been added to grain products sold
in the U.S. since 1998. But even with this supplement, it is thought
that many Americans have folate-deficient diets.
Recent research is beginning to show
relationships between folates and brain aging.
Earlier this year, Dutch scientists showed that
adults who took 800 micrograms of folic acid daily had significant
improved memory test scores, giving evidence that folates can slow
cognitive decline.
"Given the observational nature of this study, it
is still possible that other unmeasured factors also may be responsible
for this reduction in risk," said Kawas, the Al and Trish Nichols Chair
in Clinical Neuroscience. "People with a high intake of one nutrient are
likely to have a high intake of several other nutrients and may
generally have a healthy lifestyle. But further research and clinical
studies on this subject will be necessary."
Judith Hallfrisch of the U.S. Department of
Agriculture, Denis Muller with the National Institute on Aging and Ron
Brookmeyer with Johns Hopkins collaborated on the study, which was
originally undertaken at the Gerontology Research Center of the NIA and
the Department of Neurology at Johns Hopkins. Study funding came from
the Extramural Programs of the NIA.
Begun in 1958 by the NIA, the Baltimore
Longitudinal Study of Aging is America's longest-running scientific
study of human aging. BLSA scientists are learning what happens as
people age and how to sort out changes due to aging from those due to
disease or other causes. More than 1,400 men and women are study
volunteers. For more information, see:
www.grc.nia.nih.gov/branches/blsa/blsa.htm.
About the source:
About the University of California, Irvine:
Celebrating 40 years of innovation, the University of California, Irvine
is a top-ranked public university dedicated to research, scholarship and
community service. Founded in 1965, UCI is among the fastest-growing
University of California campuses, with more than 24,000 undergraduate
and graduate students and about 1,400 faculty members. The
second-largest employer in dynamic Orange County, UCI contributes an
annual economic impact of $3 billion. For more UCI news, visit
www.today.uci.edu.
UCI maintains an online directory of faculty
available as experts to the media. To access, visit
www.today.uci.edu/experts.
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