Keeping your “neuro system” young is nothing but common sense
When we think of aging, we think of the
obvious—wrinkles and achy joints, for example. We usually
don’t consider things such as worsening vision or memory loss
until we are well on our way to senior status. But we should.
After all, the disorders that may go along with the aging of
the nervous system are some of the most frightening problems
we face—dementia, Alzheimer’s disease, and macular
degeneration, for example. However, there is a way to fight
this “neuro aging.” Use dietary supplements.
DHA
DHA (docosahexaenoic acid) is an
essential fatty acid (EFA). EFAs are called “essential”
because very little can be synthesized by the body—we must
obtain them from our diet. DHA is one of the omega-3 fatty
acids, whose best-known source is perhaps fish oil.
EFAs are necessary for good health, and
DHA is well-known as one of the keys to a healthy nervous
system. DHA is the building block of human brain tissue—60
percent of the brain is fat, and DHA is the most abundant fat
in the brain, as well as in the retina of the eye. DHA is
essential in communication between the brain and nervous
system—it plays a role in the cell membrane, where the
electrical impulses that are the basis of communication within
the nervous system are generated. Without DHA and other fatty
acids, communication within this system can break down or
become less effective.
The importance of DHA to the brain and
nervous system is seen early in our development. In the first
few weeks of embryonic development, the mother’s blood
supplies the fetus with large amounts of DHA. In the last
trimester of a pregnancy, the DHA content of the brain’s
cerebrum and cerebellum—which contains centers for speech and
abstract thought—increases threefold.
DHA is recognized as extremely
important—so much so that the World Health Organization has
recommended that DHA
be added to infant formulas. Many health practitioners also
recommend it for pregnant women and nursing mothers.
DHA supplementation may be especially
important as we grow older. The body’s ability to synthesize
DHA, which is limited in all people, may decline even further
with age. This is compounded by the small amounts of DHA we
get in our diet, especially those who strive for a vegetarian
diet—the richest sources of DHA are red meats, animal organs,
and eggs.
Research indicates that low levels of DHA
may be involved in a number of health problems relating to the
nervous system.
Depression
Depression is on the rise in North
America. This is often attributed to the ups and downs of our
lives and is often seen among the aging population. However,
recent research indicates that there may be a physiological
aspect to depression that relates to nutrition.
A study published in the American
Journal of Clinical Nutrition (62 (July 1995): 1-9)
presents research indicating that omega-3 fatty acids,
specifically DHA, may reduce the risk of depression. The
authors associate the increase in depression in North America
in the past century with the decline in consumption of DHA
during the same period. To lend support to this idea, the
authors also note that there are lower rates of major
depression in those societies that consume large amounts of
fish, a key dietary source of DHA.
Dementia and Alzheimer’s disease
DHA is also being considered as a factor
in dementia and Alzheimer’s disease. In 1997, a link between
low levels of DHA and Alzheimer’s disease and memory loss was
the subject of a conference at The New York Hospital Cornell
Medical Center’s Nutrition Information Center. Among the
finding discussed at the conference was that a low level of
DHA is a significant risk factor for dementia, including
Alzheimer’s disease. Further support for this comes from
Australia. In a letter published in the Medical Journal of
Australia (153 (November 5, 1990): 563-64), Dr. Robert
Peers suggests that an imbalance between an excessive intake
of omega-6 fatty acids (from vegetable oils and margarine) and
a deficient intake of omega-3 fatty acids may be a factor in
Alzheimer’s disease.
The Japan Functional Food Research
Association has also investigated DHA and dementia. The
association notes that those with senile dementia achieved
positive results when taking DHA: in 10 of 13 cerebral
vascular dementia cases and five of five senile dementia
cases, the patients showed more than slight improvements in
psychiatric symptoms such as communication, will power,
motivation, delirium, the tendency to wander, emotional
disorders, and mental depression (www.jafra.gr.jp/DHA2-e.htm).
Vision
DHA is also the major fat in retinal
tissue. It plays a strong role in the photoreceptor cells of
the retina, suggesting an essential role for DHA in vision.
DHA deficiency in laboratory animals shows a marked decrease
in proper functioning of the visual cycle.
In a recent study looking at fish oil,
which contains DHA, and macular degeneration, researchers
found that more frequent consumption of fish appears to
protect against late age-related macular degeneration. Only a
moderate intake of fish was necessary for the protective
effect (Archives of Ophthalmology 118 (March 2000):
401-404).
Bilberry
In addition to DHA, bilberry (Vaccinium
myrtillus) is good
support for a healthy nervous system. It is closely related to
American blueberry, cranberry, and huckleberry. Although its
fruit is creamy white instead of purple, it is used in jams,
pies, cobblers, and cakes. It was bilberry jam that first
spurred interest in this fruit in something other than a
culinary sense. During the Second World War, British and
American fighter pilots hailed bilberry jam as a secret weapon
for improved night vision.
Bilberry extracts are rich in a chemical
known as anthocyanoside. These chemicals are powerful
antioxidants that appear to have a special affinity for the
eyes. Bilberry’s effect may also be related to increased
generation of rhodopsin, a purple pigment essential for
helping the eye adapt to light and dark. Bilberry appears
especially useful in reducing eyestrain and improving night
vision—ideal for those who need better “low light” vision and
those who do a lot of reading—students and computer operators,
for example.
In the 1960s, there were a number of
reports to back this up. Bilberry was investigated for its
effect on vision acuity in dim light and in night vision in
normal subjects, on the progression of cataracts, and on
patients with pigmentary retinitis (a hereditary disorder that
affects night and peripheral vision), hemeralopia (diminished
vision in bright light), macular degeneration, diabetic
retinopathy, and retinal inflammation.
Very few studies have been conducted on
bilberry since these early studies. Because some of the later
studies contradict the earlier studies, more are needed to
reconfirm the use of bilberry for vision.
Lutein and zeaxanthin
Lutein and zeaxanthin, carotenoids found
in green, leafy vegetables, are also good for the eyes. Like
other carotenoids, they are antioxidants. What is unique about
these two is that they are the only carotenoids found in the
eyes—in the macula (the part of the retina responsible for
detailed vision) and the lens. Current research is
investigating what function they may serve, and recent studies
have found that diets rich in lutein and zeaxanthin may play a
role in reducing the risk of age-related macular degeneration
and cataracts—two problems that are usually a result of the
aging process.
Macular degeneration
Those with the greatest risk for
age-related macular degeneration (AMD) tend to have a lower
amount of lutein and zeaxanthin in the eyes than those without
AMD. In the mid-1990s, one large epidemiological study (a
study that looks at a population and charts its general risk)
reported that increased consumption of lutein and zeaxanthin
reduces the risk of AMD (JAMA 272, no. 18 (1994):
1,410-23).
A study published in November 2000
supports this. In this 140-day study, it was shown that lutein
supplementation increases macular pigment—this is important
because macular pigment may protect against AMD (Investigative
Ophthalmology and Visual Science 41 (November
2000): 3,322-26). This is further confirmed in a report that
notes in the abstract that “Some observational studies have
shown that generous intakes of lutein and zeaxanthin,
particularly from certain xanthophyll-rich foods like spinach,
broccoli, and eggs, are associated with a significant
reduction in the risk for cataract (up to 20 percent) and for
age-related macular degeneration (up to 40 percent).” The
author goes on to note that further research is necessary (J
Am Coll Nutr 5 Suppl (October 19, 2000): 522S-527S).
Cataracts
Cataracts are the leading cause of vision
impairment in the United States and other developed countries.
In cataracts, the lens of the eye, which is normally colorless
and clear, grows cloudy. The lens is then unable to focus
accurately of the retina, which makes seeing more difficult.
Interestingly, lutein and zeaxanthin are the only carotenoids
generally found in the lens.
There have been three epidemiological
studies looking at the correlation between dietary lutein and
zeaxanthin and the risk of cataracts. These found a trend
toward reduced risk of cataracts and cataract surgery with
increased intake of lutein and zeaxanthin (Am J Clin Nut
70, no. 4 (1999): 517-24; Am J Epidemiol 149, no.
9: 801-9; Optom Vis Sce 77: 499-504).
How they work
Although exactly how lutein and
zeaxanthin function in the eye is not fully understood,
researchers propose that their health benefits have to do with
their antioxidant ability and their absorption of near-to-blue
UV light.
They absorb near-to-blue UV light, and
this type of light is potentially the most damaging light that
reaches the retina. As antioxidants, they inhibit the
formation of free radicals—this is important because the eye
is rich in fatty acids that are easily attacked and damaged by
free radicals.
Ginkgo
Ginkgo biloba is another supplement that
fights neuro aging. It is perhaps the best-known of the
natural substances addressed here. It has also been
extensively researched, with studies showing that ginkgo does
help maintain mental acuity.
This is largely due to its effect on
circulation. Ginkgo increases blood flow to the extremities
and the brain—there is actually an increase in cerebral blood
flow. It stands to reason that if you get an increase of blood
flow to the brain, the brain is going to get more oxygen and
more glucose. It is this increased flow of oxygen and
nutrients that is the reason why there is significant
improvement in patients with some form of dementia.
Ginkgo biloba extract (GBE) has been
studied since the 1950s. Studies reveal positive results for
what is known as “cerebral insufficiency”: a collection of
symptoms that include difficulties in concentration and
memory, absentmindedness, confusion, lack of energy,
tiredness, decreased physical performance, depressive mood,
anxiety, dizziness, tinnitus, and headache. The German
Commission E—a group of physicians, pharmacists, and
toxicologists who evaluate herbs for safety and efficacy—notes
that GBE does lead to an improvement in memory performance and
learning capacity.
Since October 1997, when the prestigious
Journal of the American Medical Association (JAMA)
reported that GBE may be beneficial in the treatment of
Alzheimer’s disease, ginkgo has received increased attention.
In 1998 and 1999, analyses of previous ginkgo studies noted
that ginkgo does positively affect cognitive functions to some
degree. A more recent study (Dement Geriatr Cogn Disord
11, no. 4 (July-August): 230-7), looked at ginkgo and dementia
in a 26-week, double-blind, placebo-controlled trial. The
abstract notes that “In comparison to the baseline values, the
placebo group showed a statistically significant worsening in
all domains of assessment, while the group receiving GBE was
considered slightly improved on the cognitive assessment and
the daily living and social behavior.”
DHA, bilberry, lutein, zeaxanthin, and
ginkgo. Five substances that add up to common sense for your
senses!
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