MONDAY, Nov. 16 (HealthDay News) -- If your
levels of vitamin D are too low, you may be at significantly increased risk for
stroke, heart disease and death, a new study suggests.
Researchers followed 27,686 people, aged 50 and older, with no history of
cardiovascular disease. The participants were divided into three groups based on
their vitamin D levels: normal (more than 30 nanograms per milliliter), low (15
to 30 nanograms per milliliter), or very low (less than 15 nanograms per
milliliter).
After one year of follow-up, those with very low levels of vitamin D were 77
percent more likely to die, 45 percent more likely to develop coronary artery
disease and 78 percent more likely to have a stroke, and twice as likely to
develop heart failure compared to people with normal vitamin D levels, the
researchers found.
"We concluded that among patients 50 years of age or older, even a moderate
deficiency of vitamin D levels was associated with developing coronary artery
disease, heart failure, stroke and death," study co-author Heidi May, an
epidemiologist with the Intermountain Medical Center in Murray, Utah, said in a
news release from the center.
"This is important because vitamin D deficiency is easily treated. If increasing
levels of vitamin D can decrease some risk associated with these cardiovascular
diseases, it could have a significant public health impact. When you consider
that cardiovascular disease is the leading cause of death in America, you
understand how this research can help improve the length and quality of people's
lives," May added.
Because this was an observational study, a definitive link between vitamin D
levels and heart disease couldn't be established, but the findings point to the
need for further research, said study co-author Dr. Brent Muhlestein, director
of cardiovascular research at Intermountain's Heart Institute.
"We believe the findings are important enough to now justify randomized
treatment trials of supplementation in patients with vitamin D deficiency to
determine for sure whether it can reduce the risk of heart disease," Muhlestein
said in the news release.
The study was to be presented Monday at the American Heart Association's annual
meeting in Orlando, Fla.
Vitamin D is obtained from sunlight and by consuming fatty fish or fortified
dairy products, including milk.
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.
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.
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.
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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