The
All Mighty Blueberry!
The health benefits of fruits and vegetables are well-known, especially
with respect to cardiovascular disease and certain kinds of cancer.
Fruits and vegetables may also have important effects on other
body systems and diseases. We wanted to find out if fruits and
vegetables could change how age affects brain function. We were
particularly interested in the effects on motor function (coordination
and movement) and cognitive function (learning and memory) because
problems in these areas are common in elderly people
.
Rats also experience changes in motor and cognitive function as
they age. The changes occur within months rather than years because
of the shorter life span of the rat. In one study, aged rats had
decreased performance on a balancing test that uses a device called
a rotor rod to evaluate motor function. In a water maze test,
which evaluates cognitive function, younger rats had little difficulty,
but older rats took longer to complete the test.
Several factors might be responsible for age-related changes in
motor and cognitive function. The sensitivity of certain receptors
that trigger brain processes may be decreased. There may be alterations
in the cellular environments. The signals themselves may be altered.
Oxidative stress may also produce age-related changes in motor
and cognitive behavior. With age, the brain becomes more sensitive
to oxidative stress and possibly inflammation. This increased
sensitivity may be due to decreases in the amount or activity
of naturally-occurring antioxidants. Age-related changes in the
structure or function of brain membranes may also play a role.
Finally, because the brain does not age uniformly, the sensitivity
to oxidative stress may vary depending on the type of receptors
that are present in the particular area of the brain.
We wanted to find out if fruits and vegetables could alter the
effects of aging on the brain. We were especially interested in
berries because they contain high levels of natural antioxidants.
We fed pelletized extracts of blueberries, strawberries, or spinach
to 19 month old rats for 8 weeks. (Motor and cognitive deficits
have already appeared by the time rats are 19 months old.) When
corrected for the difference in body size between rats and humans,
the amounts fed the rats were similar to what a human would normally
eat: about one-half to one cup of blueberries, a pint of strawberries,
or a large spinach salad. We studied the effects on learning,
motor behavior, memory, and certain cell functions that are sensitive
to aging and oxidative stress.
All of the supplemented diets had beneficial effects on water
maze performance, but only blueberry supplementation affected
motor performance, as shown by improvement on the rotor rod test.
The spinach-supplemented rats showed the most improvement on a
motor learning test that required both cognitive and motor function.
However, when we looked at the actual running times, we found
that these results were misleading: the rats supplemented with
either strawberries or blueberries had run the test so quickly
the first time that there was little room for improvement.
In order to more closely duplicate the average human diet, we
repeated the study, replacing the specially-formulated diet with
one based on corn and other grains. In addition, we used both
cultivated and wild blueberries. Both types of blueberries increased
motor performance, showing that blueberries had beneficial effects
even as a supplement to a well-balanced diet. Interestingly, preliminary
findings indicated that the blueberry-supplemented rats had a
lower incidence of age-related changes, such as inflammation,
in their leg muscles.
Certain types of radiation can cause changes in the brain that
are similar to those of aging. We supplemented rats with a diet
containing either strawberries or blueberries for eight weeks
prior to being irradiated. The results indicated that the effects
of the radiation were blocked. Precisely how blueberries caused
these changes is not known, but there are many possible pathways.
For example, the protective effects might have been caused by
increases in antioxidant or antiinflammatory activity, increases
in vital cell functions and reactions, or increases in the brain’s
neural connections.
Anthocyanins and hydroxycynamic acids are two of the most common
polyphenolic families—groups of related chemical compounds—found
in blueberries. We wanted to find out if either of these was responsible
for the anti-aging effects of blueberries. After chemically separating
each compound from whole blueberries, we administered them orally
to rats. Plasma anthocyanin and hydroxycynamic acid levels were
highest immediately after administration, then slowly decreased.
The peak anthocyanin level was higher than that of hydroxycynamic
acid. The antioxidant effect was measured by assessing free radical
production in red blood cells exposed to oxidative stress. Initially,
anthocyanin administration caused a 20% lowering of the free radical
levels in the red blood cells. This effect continued for as long
as 24 hours, even though anthocyanin levels decreased. Hydroxycynamic
acid did not produce this response, suggesting that anthocyanin
had a greater capacity to penetrate the cells. A subsequent experiment
showed this to be the case. Thus, we hypothesize that anthocyanin
compounds are responsible for at least some of the beneficial
effects of blueberries.
Finally, we explored the effects of blueberry supplementation
in a mouse model of Alzheimer’s disease. This disease, which
is characterized by increased sensitivity to oxidative stress,
is superimposed upon an aged brain that is already more vulnerable
to oxidative stress and inflammation. The net effect is severe
cognitive dysfunction. Groups of Alzheimer’s mice and normal
mice were fed a standard balanced diet plus blueberries from the
time they were weanlings until they were 12 months of age. Other
groups were fed the standard diet without blueberries. At the
end of the study, we found that only 45% of the Alzheimer’s
mice without blueberry supplementation could perform adequately
on a Y-maze test. In the normal mice (with and without blueberry
supplementation), 59% of the animals performed the test correctly.
In the blueberry-fed Alzheimer’s mice, the completion rate
was 61%--essentially the same as the normal rats. Blueberry supplementation
did not decrease the incidence of abnormalities usually associated
with Alzheimer’s disease, such as amyloid deposits. However,
supplementation did prevent the loss of brain communication networks
that are essential for learning and memory function.
Our findings suggest that the beneficial effects of blueberry
supplementation may be both direct and indirect. The indirect
effects involve antioxidant and anti-inflammatory activities that
could eventually alter communication between brain cells. However,
nutrients found in blueberries may also produce direct effects
on brain communications and signaling that could lead to improved
cognitive and motor performance. Clearly, the old phrase “you
are what you eat” could become more important than ever
as we strive toward successful aging.
Be watching for our Blueberry supplements coming
out very soon!
Bruce Brightman – founder
LifeSource
