Blueberries
By Russell Martin
Life Extension Magazine February 2006
When it comes to brain protection, there is nothing quite like
blueberries,” according to James Joseph, PhD, lead scientist in the
Laboratory of Neuroscience at the USDA Human Nutrition Research Center
on Aging at Tufts University. “Call the blueberry the brain berry,” says
Dr. Joseph.Dr. Joseph’s claim was made with the publication of his landmark
blueberry research. It has since been bolstered by animal studies
demonstrating that daily consumption of modest amounts of blueberries
dramatically slows impairments in memory and motor coordination that
normally accompany aging. Moreover, a wealth of exciting new research
clearly establishes that in addition to promoting brain health, this
long-prized native North American fruit—whether consumed fresh, frozen,
canned, or as an extract—may confer a range of diverse health benefits.
After testing 24 varieties of fresh fruit, 23 vegetables, 16 herbs
and spices, 10 different nuts, and 4 dried fruits, the US Department of
Agriculture determined that blueberries scored highest overall in total
antioxidant capacity per serving. As most health-conscious adults are
aware by now, antioxidants are vital in countering free radicals, the
harmful byproducts of cellular metabolism that can contribute to cancer
and other age-related diseases.
Separate studies show that blueberries may help to lower blood cholesterol,
promote urinary tract health, and reduce the risk of urinary infections
., Studies
in Europe have documented the relationship between consumption of
bilberries (the blueberry’s close European cousin) and eye health,
highlighting the berries’ ability to improve night vision, halt cataract
progression, and protect against glaucoma.
New studies also support blueberries’ ability to reduce age-associated lipid peroxidation,
a contributor to cardiovascular disease, and to suppress the growth of several types of cancer cells,
suggesting that blueberry phytochemicals may well play a future role in
human cancer treatment. And you can add to the manifold health benefits
of blueberries at least one more reason to eat them daily: virtually
everyone agrees that they are delicious.
When the Plymouth colonists arrived in what is now Massachusetts,
native American inhabitants shared with them the blue-tinged fruit of a
low woody shrub whose calyx forms a delicate five-point star. For
centuries, native American cultures had consumed “star berries” not only
as food but also as medicine, drinking blueberry juice to relieve
coughs, brewing a tea from blueberry leaves as a tonic, and eating
fresh, dried berries to sharpen their vision.
Blueberries and bilberries belong to the genus Vaccinium, which
includes more than 450 plants grown in all parts of the world. Members
of the Vaccinium genus possessing the darkest-colored fruits appear to
provide the greatest health benefits, a fact that scientists attribute
to the compounds that give the plants their dark pigmentation. These
bioflavonoids include anthocyanins and their precursor,
proanthocyanidins, both of which are voracious scavengers of free
radicals., Research demonstrates that blueberry consumption boosts serum antioxidant status in humans. Elevated antioxidant levels in the body may protect against damage to
cells and cellular components, thus helping to reduce the risk of many
chronic degenerative diseases.
How Blueberries Combat Brain Aging
In Dr. Joseph’s groundbreaking work at Tufts, 19-month-old
laboratory rats—the equivalent of 60- to 65-year-old humans—were fed
dried blueberry extract at a dose the investigators calibrated to be the
human equivalent of one-half cup of blueberries per day. Three other
groups of rats received spinach extract, strawberry extract, or a
control diet. After eight weeks on the regimen, the investigators
evaluated the rats—now equivalent in age to 70- to 75-year-old
humans—using various tests of memory function.
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Compared to a control group fed only a standardized diet, each of
the three supplemented groups performed at least marginally better on
memory and learning tests.In
tests of neuromotor function, however, the blueberry-fed rats
significantly outperformed the other groups. These rats were much better
able to walk the length of a narrow rod and balance on an accelerating
rotating rod compared to the other groups. This was indeed a stunning
finding, as scientists have for some time tended to accept as
established fact that age-related neuromotor dysfunction is
irreversible. Dr. Joseph’s findings appear to flatly contradict this
notion. Blueberry extract, he discovered, was clearly capable of
reversing this particular aging process as no other agent had ever been
demonstrated to do. Dr. Joseph concluded:
“This is the first study that has shown that dietary
supplementation with fruit and vegetable extracts that are high in
phyto-nutrient antioxidants can actually reverse some of the
aging-relatedneuronal/behavioral dysfunction.”
Dr. Joseph’s blueberry-supplemented rats also demonstrated improved
learning and memory skills as they navigated mazes and found—and then
remembered—the location of an underwater platform on which they could
rest from swimming. When Dr. Joseph and his colleagues examined the
brain tissues of these rats in vitro, they found that dopamine levels
were much higher than in the brains of rats in the other groups.
Dopamine is an essential neurotransmitter that enables smooth,
controlled movements as well as efficient memory, attention, and
problem-solving function. Dr. Joseph speculated that blueberry extract
might also increase brain cell membrane fluidity while reducing levels
of inflammatory compounds, thus slowing the brain’s normal aging
process.
To other researchers, Dr. Joseph’s study seemed especially
promising in its implications for aging humans. Older adults tend to
fall or stumble—sometimes with catastrophic consequences—because their
brains become less adept at monitoring and modulating swaying motion, as
conduction of neural signals in the brain slows with aging. Older
people likewise tend to suffer memory loss and an inability to learn new
behaviors in ways that can starkly limit their ability to lead
productive, satisfying lives. “People are told once you’re old, there’s
nothing you can do,” noted Dr. Joseph’s colleague and study coauthor Dr.
Barbara Shukitt-Hale. “That might not be true.”
New Studies Confirm Brain Benefits
Dr. Joseph’s findings not only spurred scientific research into the
health properties of blueberries, but also greatly increased public
awareness of this remarkable fruit. Five important new studies support
and expand on Dr. Joseph’s original research.
In a 2005 article published in the journal Neurobiology of Aging,
Rachel Galli and her colleagues, also based at Tufts, reported
discovering a specific mechanism by which blueberries help reverse the
neurological aging process.The Galli study—which included Drs. Joseph and Shukitt-Hale as
co-investigators—sought to measure the heat-shock protein response in
the brains of both young and aged rats supplemented with blueberry
extract compared to a control group of aged rats. A protective mechanism
produced in the brains of most animals (and humans), heat-shock
proteins fight free radicals and inflammation-inducing agents, acting
similarly to antioxidants to support healthy brain tissues. As people
age, however, their ability to generate heat-shock proteins in
sufficient quantity declines,17
sometimes dramatically. The Tufts researchers sought to determine
whether blueberries could help restore the heat-shock protein response
in rats.
After 10 weeks, the scientists subjected brain tissues from the
rats to an inflammatory challenge and then measured the subsequent
heat-shock protein response. As presumed, the brains of young rats that
had consumed blueberries produced a strong heat-shock protein response,
unlike the brains of the aged rats that did not consume blueberry
extract. The significant finding, however, was that the brains of aged
rats fed blueberries were as successful at initiating the heat-shock
protein response as the brains of young rats. The blueberry extract
proved capable of entirely restoring the heat-shock protein response in
the test animals, suggesting that blueberries may protect against
neurodegenerative processes associated with aging.
Last year, the journal Nutritional Neuroscience published an
important new study by scientists at the University of Barcelona. The
Spanish researchers previously had demonstrated blueberries’
effectiveness in reversing age-related deficits in neuronal signaling.
They now sought to determine whether the active phytochemicals that give
blueberries their significant neurological benefits do indeed cross the
blood-brain barrier. Examining the brains of rats that had been fed
blueberry extract for 10 weeks, they were able to isolate
blueberry-specific agents in the rats’ cerebellum, cortex, hippocampus,
and striatum—brain areas that control memory and learning processes.
Most striking, the scientists were able to correlate the presence of
blueberry phytochemicals in the rat brain cortices they examined with
improved cognitive performance in tests initiated at the end of the
10-week supplementation period.
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Blueberries may also prove capable of helping humans whose brains
have been damaged by a loss of blood flow and the critical oxygen and
nutrients it provides, a condition known as ischemia (one of the two
principal causes of stroke). In a May 2005 study published in the
journal Experimental Neurology, researchers documented how
three groups of rats whose diets were supplemented with blueberries,
spinach, and spirulina, respectively, all suffered less brain cell loss
and were better able to recover lost function following artificially
induced ischemia than rats in a non-supplemented control group. At
autopsy, the scientists observed that the physical extent of ischemic
damage to the brains of rats that had been fed the three supplements was
significantly less than that suffered by the control group.
Similarly, the Tufts scientists who have been in the forefront of
blueberry research reported an additional study in the August 2005 issue
of Neurobiology of Aging. In this study, they demonstrated
that the auditory processing speed of aged rats supplemented with
blueberries nearly matched the lightning-fast auditory processing speeds
of young rats, while the speeds of a control group of non-supplemented
aged rats were dramatically slower. According to the researchers, “These
results suggest that the age-related changes in temporal processing
speed in [the primary auditory cortex] may be reversed by dietary
supplementation of blueberry phytochemicals.”
Another recent study suggests that blueberries may have
applications in the developing field of neural transplants, which many
neuroscientists believe hold promise as a means of replacing vital brain
structures destroyed or damaged by brain injury or degenerative
disease. Unfortunately, the survival of transplanted tissue is often
poor, especially in older recipients. When researchers gave blueberry
supplements to middle-aged rats receiving neural implants, the growth of
their hippocampal grafts was markedly more vigorous than that of
identical grafts in a control group, and cellular organization was
comparable to that in tissue grafted into young laboratory animals.
Blueberries may someday play an important role in ensuring that
surgically grafted tissues thrive in the new host, where they may help
to restore lost motor and cognitive functions.
Benefits for Other Body Systems
Blueberries’ benefits for
neurological health and vigor are so well established as to make daily
consumption of the fruit a “no-brainer” for virtually everyone.
Moreover, new studies continue to confirm blueberries’ remarkable
health-promoting effects in other areas of the human body.
For
decades, researchers in Europe have documented evidence of the ability
of bilberries to combat a range of eye disorders. During World War II,
French researchers who examined bilberry extract’s effects in pilots
found that bilberry helped improve nighttime visual acuity, adjustment
to darkness, and recovery from glare.6
In another study, all eight patients with glaucoma who were given a
single oral dose of bilberry extract demonstrated improvements based on
electroretinography, a measure of electrical responsiveness of the
retinal cells. Bilberry’s antioxidant properties may protect against
glaucoma by supporting healthy intraocular pressure.6
In a clinical study, the combination of bilberry extract with vitamin E
stopped the formation of senile cortical cataracts in 48 of 50
patients.6 Researchers believe
that the anthocyanins and proanthocyanidins found in blueberries might
similarly offer benefits for eye health.
In an article in the Journal of Agricultural and Food Chemistry
in 2004, researchers announced that they had isolated three compounds
in blueberries and other dark-pigmented berries known to lower
cholesterol levels. In a
follow-up study, one of the three phytochemicals—pterostilbene—showed a
particularly potent effect in stimulating a receptor protein in cells
that plays an important role in lowering cholesterol and other blood
fats.3 “We are excited to learn
that blueberries, which are already known to be rich in healthy
compounds, may also be a potent weapon in the battle against obesity and
heart disease,” lead author Agnes Rimando told members of the American
Chemical Society.
Blueberry
juice or extract may help avert urinary tract infections commonly
suffered by women. Scientists formerly hypothesized that dark-pigmented
berries such as cranberry help fight infection through an antibacterial
effect caused by the acidification of urine.4
Current research suggests that berries, including cranberry and
blueberry, may fight bacterial urinary infections by preventing E. coli
and other forms of bacteria from adhering to cells lining the walls of
the urinary tract.
Blueberries
also may slow the growth of cancer cells. In 2001, University of
Mississippi researchers conducting in-vitro tests found that blueberry
and strawberry extracts were remarkably successful in slowing the growth
of two aggressive cervical cancer cell lines and two fast-replicating
breast cancer cell lines, with the blueberry extract performing best
against the cervical cancer cells.
Last year, a University of Georgia study similarly demonstrated
blueberry extract’s ability to inhibit cell proliferation in two
separate lines of colon cancer cells, reducing by more than 50% the rate
at which the cells otherwise multiplied. Further studies are indicated to determine whether phytochemicals from
dark-pigmented berries may affect very early growth of malignant cells
in the bodies of humans as well.
Sources: http://www.lef.org/Magazine/2006/2/report_blueberries/Page-01