Eye Sight
: Your Eye and Brain Connection Think Quick and Look Sharp

By Robert Abel, Jr, MD
It is no surprise how much the eyes and the brain
have in common when you realize the retina is actually
an extension of the brain. Furthermore, 40 percent of
the brain is devoted to processing the information that
comes into the eye. A recent study indicates that the eye
and brain are so intimately connected that an electrical
test can detect depression through the eye. Therefore,
it should also come as no surprise that the nutrients
important for one are important for the other. One
example is fat—that is to say, healthy fat. The brain is
comprised of 60 percent essential fatty acids, while the
retina has one of the highest omega-3 concentrations in
the body. By incorporating a few key nutrients into your
diet, you can help keep your eyes and brain at their best.
The Basics
The eye is a bag of water with
two lenses, the cornea and the
crystalline lens, which focus
light onto the retina. The retinal
photoreceptors receive the
images and send them through
the optic nerve to the brain. With
about 1 million ganglion cells, the
human retina can transmit data
at approximately the rate of an
Ethernet connection.
Eighty percent of our sensory
perception comes to us through
our eyes. There are 100 times more
nerve fibers devoted to vision than
to hearing. The retinal receptors
transform incoming light into
electrical signals. While doing this,
the rods and cones get oxidized and
need to be immediately replenished.
Since light, especially UV light, is
an oxidant and the retina has the
highest oxygen demand in the body,
the eyes require a constant source
of antioxidants.
The brain is the center of
thinking, breathing, heart rate,
and the unconscious. The cerebral
cortex governs higher thinking
and puts together what we feel and
how we react to it. The autonomic
nervous system controls organ
function and whether we become
nervous or relaxed. Deep in the
brain, the amygdala is the emotional
center and the hippocampus
regulates memories. The brain
requires antioxidants and other
vitamins and nutrients to function
optimally. Vitamins D and E,
DHA, and lutein are particularly
important for both eye and brain
health.
Supplemental Support
Vitamin D3 is formed when UV
light meets cholesterol molecules.
A recent study finds that 75 percent
of American teens and adults are
deficient in this important vitamin.
Adequate levels of vitamin D are
related to a reduced risk of insulin
resistance and Type 2 diabetes,
asthma, tuberculosis, cancer, and
Parkinson’s disease. Vitamin D is
essential for bone and heart health,
and it even improves immunity.
Serum levels of D are inversely
associated with early macular
degeneration (whereas fish intake is
inversely associated with advanced
macular degeneration). Vitamin
D also helps protect the brain by
preventing cognitive decline.
Vitamin E is an important
antioxidant that blocks the
breakdown of essential fats in
cell membranes. It’s found in the
retina and the lens. Studies find
that people with an adequate level
of vitamin E have a reduced rate
of cataract formation. Vitamin
E is also associated with higher
cognitive performance and memory
retention. It is important to
remember that natural vitamin E
(d-alpha tocopherol) is significantly
more potent than synthetic.
Lutein is a carotenoid found
in the macula (the center of the
retina). It is a crucial protector
against macular degeneration
and cataracts. Lutein protects the
rods and cones from free-radical
damage caused by UV light. Like
the other carotenoids, lutein is a
fat-soluble nutrient that requires a
small amount of cholesterol to be
transported to the retina. Lutein is
a powerful antioxidant that protects
every cell in the body—including
the brain—from the damage caused
by free radicals.
Don’t Forget Healthy Fat
Only when the great apes began
eating fish did the primate brain
grow from 400 cubic centimeters
to 1,300 to 1,500 cubic centimeters.
Principally, it is the deep-water,
algae-eating fatty fish like salmon,
herring, and cod that provide the
essential nutrient that’s necessary
for the development of all organs,
especially the eye and the brain.
Every cell membrane in the body
is made of two layers of good fats;
one layer is omega-3/DHA and
the other is omega-6. However,
in the retina, both layers of the
retinal receptor membranes and
the mitochondrial membranes are
made of DHA. In fact, 50 percent
of the retina is comprised of that
fatty acid.
Omega-6 fatty acids are found in
all terrestrial plants and meat from
animals that feed on corn and grain.
Algae and plankton are the major
source of omega-3, but animals
that graze freely are able to convert
linolenic acid into DHA.
DHA has been widely studied,
and benefits include a reduced
risk of depression and insulin
resistance, reduced inflammation,
prevention of arrhythmia and
heart disease, reduced LDL
cholesterol and triglycerides, and
neuroportection within five hours
of an ischemic stroke.
DHA is essential for normal
eye development and function.
Deficient DHA levels contribute to
macular degeneration and retinitis
pigmentosa, which is caused
by a progressive loss of retinal
photoreceptors. DHA also offers
cognitive support. Adequate levels
contribute to normal development
of the brain and nervous system
and support memory. Infants who
receive DHA supplementation in
utero are found to have a higher IQ,
larger head size, and better vision
at age four.
We are seeing much more vision
loss and dementia as the nutrition
value of our food decreases.
Omega-6 rich food is more
abundant and cheaper, and healthy
fish are sometimes difficult to
obtain. To assure an adequate level
of DHA, a diet rich in fatty, coldwater
fish or supplementation with
marine oil is imperative. (For more
information, see my book The DHA
Story.) Add the nutrients listed
above, and help protect your eyes
and brain for years to come.
The DHA Story by Robert Abel, Jr., MD (Basic Health, 2002) Eye Advisory, www.eyeadvisory.com “Randomized Trial of Vitamin D Supplementation to Prevent Seasonal Influenza A in Schoolchildren” by M. Urashima et al., Am J Clin Nutr, 3/10 • “Seeing Gray when Feeling Blue? Depression Can Be Measured in the Eye of the Diseased” by E. Bubl et al., Biol Psychiatry, 2010