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In the News
Fish Oil
May Help Prevent Alzheimer's
The omega-3 fatty acids found in fish oil might play an
important role in preventing Alzheimer's disease, according
to a research team at the University of California, Los
Angeles (UCLA). Published in the Dec. 26 issue of the
Journal of Neuroscience, the scientists demonstrated that
the omega-3 fatty acid docosahexaenoic acid (DHA) increases
the production of LR11, a protein that is found at reduced
levels in Alzheimer's patients. LR11 is known to destroy the
protein that forms the plaques associated with the disease,
the researchers explained.
The plaques are actually a buildup of a protein called beta
amyloid, which is thought to be toxic to brain cells. Higher
levels of LR11 prevent the manufacturing of the toxic
proteins, which is why researchers believe the low levels
found in the brains of Alzheimer's patients may be a
contributing factor to the disease.
Alzheimer's is a debilitating neurodegenerative disease that
causes memory loss, dementia, personality change and
ultimately death. The Alzheimer's Association estimates that
5.1 million Americans are currently afflicted with the
disease. The association predicts that may increase to
between 11 million and 16 million people by 2050.
The researchers tested the effects of DHA by adding it
directly to human and animal neurons grown in the
laboratory.
"We found that even low doses of DHA increased the levels of
LR11 in rat neurons, while dietary DHA increased LR11 in
brains of rats or older mice that had been genetically
altered to develop Alzheimer's disease," lead researcher
Greg Cole, associate director of UCLA's Alzheimer Disease
Research Center, said in a prepared statement.
Fatty acids such as DHA are considered essential fatty
acids, because the body cannot make them from other sources
and must obtain them through diet. Years of research have
shown that DHA is the most abundant essential fatty acid in
the brain, Cole said, and that it is critical to fetal and
infant brain development. Studies have also linked low
levels of DHA in the brain to cognitive impairment and have
shown that lower levels may increase oxidative stress in the
brains of Alzheimer's patients.
The research team acknowledged that their work does not
identify a dosage of DHA that people could take to prevent
Alzheimer's, but they recommend eating more fatty fish or
taking a supplement. They did not recommend taking DHA to
try to slow the progression of Alzheimer's.
Flax Seed May
Slow Prostate cancer
A new study commissioned by the National
Institute of Health shows real promise for a
nutritional aid in the fight against
prostate cancer.
The flaxseed study was aimed at fighting prostate cancer,
not treating a side effect. The edible seed has been used
for hundreds of years in cereals and breads and is high in
beneficial omega-3 fatty acids and in lignan, a substance
that can affect hormone levels and perhaps squelch their
cancer-promoting effects.
Four groups of about 40 men who were scheduled to have their
prostates removed three weeks later were assigned to get
either 30 grams of powdered flaxseed, a low-fat diet, both
or neither until their surgery.
After the men's prostates were removed, researchers found
that tumors had been growing 30 to 40 percent slower in the
two groups taking flaxseed, based on how quickly cells were
multiplying. Low-fat diets had no effect on this, said Wendy
Demark-Wahnefried of Duke University Medical Center, who led
the study.
"Our findings are compelling but they're preliminary," she
cautioned. But several doctors said flaxseed is nutritious
and seems to have little downside other than a sawdust-like
consistency, since it must be used ground or powdered
because it has an inedible hull or coating. Scientists plans
to study flaxseed on men with prostate cancer that comes
back after initial treatment, and Canadian scientists also
are testing it for breast cancer, she said.
Vitamin D deficiency tied to higher blood pressure
Low blood concentrations of
vitamin D may be associated with higher
blood pressure in whites, indicating a risk
of developing hypertension, or high blood
that requires medical treatment, researchers
report. However, this relationship was not
noted among blacks.
"Though easily corrected by taking a vitamin D supplement
or having causal sunlight exposure, vitamin D insufficiency
is highly prevalent in the United States," Dr. Vin
Tangpricha told Reuters Health.
Tangpricha and colleagues, all from Emory University
School of Medicine in Atlanta, looked at the association
between systolic blood pressure - the top number of the
blood pressure reading representing the pressure during
contraction of the heart muscle -- and vitamin D levels
among 7,699 adults without high blood pressure. Forty-seven
percent were male, 61 percent were white, and 39 percent
were black.
The study population had participated in the third
National Health and Examination Survey conducted from 1988
to 1994, which provides the most recent nationally
representative data on vitamin D concentrations among U.S.
adults, the investigators report in the American Journal of
Clinical Nutrition.
Overall, 61 percent of whites and 92 percent of blacks
had vitamin D deficiency. Most (63 percent) of the
participants were 18 to 49 years old, and 37 percent were 50
years or older when systolic blood pressure and vitamin D
measurements were obtained.
The investigators found that white participants with
sufficient vitamin D levels had a 20-percent lower rise in
age-associated systolic blood pressure compared with those
with insufficient vitamin D levels. This relationship was
not statistically significant in blacks.
"This paper does not provide direct evidence that vitamin
D supplementation will lower blood pressure," Tangpricha
cautions.
He and colleagues suggest that further research examine
in more detail how vitamin D status affects blood pressure
in black and white populations. Improved methods for
detecting vitamin D deficiency are also necessary, they
conclude.
SOURCE: American Journal of
Clinical Nutrition, January 2008.
Higher Folate Levels Linked
to Reduced Risk for Alzheimer’s Disease
ScienceDaily (Jan. 9,
2007) — Individuals who take in higher
levels of the nutrient folate through both
diet and supplements may have a reduced risk
of developing Alzheimer’s disease, according
to a report in the January issue of Archives
of Neurology, one of the JAMA/Archives
journals.
By the year 2047, the
prevalence of Alzheimer’s disease is
expected to quadruple. Delaying the onset of
this neurodegenerative disease would
significantly reduce the burden it causes.
Researchers suspect that elevated levels of
the amino acid homocysteine in the blood,
which is linked to a higher risk for
cardiovascular disease and stroke, may also
increase the risk for Alzheimer’s disease.
Folate, vitamin B12 and vitamin B6, are
important in the body’s processing of
homocysteine – therefore, deficiencies in
these nutrients increase homocysteine levels
and may contribute to cardiovascular
disease, stroke and dementia.
José A. Luchsinger, M.D.,
Columbia University Medical Center, New
York, and colleagues examined, interviewed
and assessed the diets of 965 individuals
without dementia between 1992 and 1994 and
then followed them for an average of 6.1
years to see if they developed Alzheimer’s
disease. The participants had an average age
of 75.8 and 70.2 percent were women, 32.6
percent African-American, 45.3 percent
Hispanic and 22.1 percent white.
During the follow-up period, 192 of the
participants developed Alzheimer’s disease. When the
individuals were divided into four groups based on the total
level of folate they took in through food and supplements
and the analysis was adjusted for patient characteristics,
comorbid diseases and B12 and B6 intake, the risk of
Alzheimer’s disease was lower in the groups with higher
intake. Neither dietary folate nor supplements alone were
significantly linked to Alzheimer’s disease risk; only the
two in combination appeared to produce an effect. Levels of
the vitamins B12 and B6 were not associated with Alzheimer’s
disease risk.
Higher folate intake was modestly
correlated with lower homocysteine levels, “indirectly
suggesting that a lower homocysteine level is a potential
mechanism for the association between higher folate intake
and a lower Alzheimer’s disease risk,” the authors write.
Definitive conclusions about the role of
folate in the development of Alzheimer’s disease cannot yet
be made. The findings of this study are in contrast to those
of some other research, and other compounds (such as
hormones) perceived to reduce the risk for dementia in
observational studies did not do so in randomized trials.
Thus, the decision to increase folate intake to prevent
Alzheimer’s disease should await clinical trials.
Adapted from materials provided by JAMA
and Archives Journals, via EurekAlert!, a service of AAAS.
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