Biology Talk

rpautrey2 · Guest

Scientists learn how food affects the brain
July 09, 2008

In addition to helping protect us from heart disease and cancer, a
balanced diet and regular exercise can also protect the brain and ward
off mental disorders.

"Food is like a pharmaceutical compound that affects the brain," said
Fernando Gómez-Pinilla, a UCLA professor of neurosurgery and
physiological science who has spent years studying the effects of
food, exercise and sleep on the brain. "Diet, exercise and sleep have
the potential to alter our brain health and mental function. This
raises the exciting possibility that changes in diet are a viable
strategy for enhancing cognitive abilities, protecting the brain from
damage and counteracting the effects of aging."

Gómez-Pinilla analyzed more than 160 studies about food's affect on
the brain; the results of his analysis appear in the July issue of the
journal Nature Reviews Neuroscience.

Omega-3 fatty acids — found in salmon, walnuts and kiwi fruit —
provide many benefits, including improving learning and memory and
helping to fight against such mental disorders as depression and mood
disorders, schizophrenia, and dementia, said Gómez-Pinilla, a member
of UCLA's Brain Research Institute and Brain Injury Research Center.

Synapses in the brain connect neurons and provide critical functions;
much learning and memory occurs at the synapses, Gómez-Pinilla said.

"Omega-3 fatty acids support synaptic plasticity and seem to
positively affect the expression of several molecules related to
learning and memory that are found on synapses," Gómez-Pinilla said.
"Omega-3 fatty acids are essential for normal brain function.

"Dietary deficiency of omega-3 fatty acids in humans has been
associated with increased risk of several mental disorders, including
attention-deficit disorder, dyslexia, dementia, depression, bipolar
disorder and schizophrenia," he said. "A deficiency of omega-3 fatty
acids in rodents results in impaired learning and memory."

Children who had increased amounts of omega-3 fatty acids performed
better in school, in reading and in spelling and had fewer behavioral
problems, he said.

Preliminary results from a study in England show that school
performance improved among a group of students receiving omega-3 fatty
acids. In an Australian study, 396 children between the ages 6 and 12
who were given a drink with omega-3 fatty acids and other nutrients
(iron, zinc, folic acid and vitamins A, B6, B12 and C) showed higher
scores on tests measuring verbal intelligence and learning and memory
after six months and one year than a control group of students who did
not receive the nutritional drink. This study was also conducted with
394 children in Indonesia. The results showed higher test scores for
boys and girls in Australia, but only for girls in Indonesia.

Getting omega-3 fatty acids from food rather than from capsule
supplements can be more beneficial, providing additional nutrients,
Gómez-Pinilla said.

Scientists are learning which omega-3 fatty acids seem to be
especially important. One is docosahexaenoic acid, or DHA, which is
abundant in salmon. DHA, which reduces oxidative stress and enhances
synaptic plasticity and learning and memory, is the most abundant
omega-3 fatty acid in cell membranes in the brain.

"The brain and the body are deficient in the machinery to make DHA; it
has to come through our diet," said Gómez-Pinilla, who was born and
raised in salmon-rich Chile and eats salmon three times a week, along
with a balanced diet. "Omega-3 fatty acids are essential."

A healthy diet and exercise can also reduce the effect of brain injury
and lead to a better recovery, he said.

Recent research also supports the hypothesis that health can be passed
down through generations, and a number of innovative studies point to
the possibility that the effects of diet on mental health can be
transmitted across generations, Gómez-Pinilla said.

A long-term study that included more than 100 years of birth, death,
health and genealogical records for 300 Swedish families in an
isolated village showed that an individual's risk for diabetes and
early death increased if his or her paternal grandparents grew up in
times of food abundance rather than food shortage.

"Evidence indicates that what you eat can affect your grandchildren's
brain molecules and synapses," Gómez-Pinilla said. "We are trying to
find the molecular basis to explain this."

Controlled meal-skipping or intermittent caloric restriction might
provide health benefits, he said.

Excess calories can reduce the flexibility of synapses and increase
the vulnerability of cells to damage by causing the formation of free
radicals. Moderate caloric restriction could protect the brain by
reducing oxidative damage to cellular proteins, lipids and nucleic
acids, Gómez-Pinilla said.

The brain is highly susceptible to oxidative damage. Blueberries have
been shown to have a strong antioxidant capacity, he noted.

In contrast to the healthy effects of diets that are rich in omega-3
fatty acids, diets high in trans fats and saturated fats adversely
affect cognition, studies indicate.

Junk food and fast food negatively affect the brain's synapses, said
Gómez-Pinilla, who eats fast food less often since conducting this
research. Brain synapses and several molecules related to learning and
memory are adversely affected by unhealthy diets, he said.

Emerging research indicates that the effects of diet on the brain,
combined with the effects of exercise and a good night's sleep, can
strengthen synapses and provide other cognitive benefits, he added.

In Okinawa, an island in Japan where people frequently eat fish and
exercise, the lifespan is one of the world's longest, and the
population has a very low rate of mental disorders, Gómez-Pinilla
noted.

Folic acid is found in various foods, including spinach, orange juice
and yeast. Adequate levels of folic acid are essential for brain
function, and folate deficiency can lead to neurological disorders
such as depression and cognitive impairment. Folate supplementation,
either by itself or in conjunction with other B vitamins, has been
shown to be effective in preventing cognitive decline and dementia
during aging and enhancing the effects of antidepressants. The results
of a recent randomized clinical trial indicate that a three-year folic
acid supplementation can help reduce the age-related decline in
cognitive function.

In patients with major depression and schizophrenia, levels of a
signaling molecule known as brain-derived neurotrophic factor, or
BDNF, are reduced. Antidepressants elevate BDNF levels, and most
treatments for depression and schizophrenia stimulate BDNF. Here, too,
omega-3 fatty acids are beneficial, as is the curry spice curcumin,
which has been shown to reduce memory deficits in animal models of
Alzheimer's disease and brain trauma. BDNF is most abundant in the
hippocampus and the hypothalamus — brain areas associated with
cognitive and metabolic regulation.

The high consumption of curcumin in India may contribute to the low
prevalence of Alzheimer's disease on the subcontinent.

In humans, a mutation in a BDNF receptor has been linked to obesity
and impairments in learning and memory.

"BDNF is reduced in the hippocampus, in various cortical areas and in
the serum of patients with schizophrenia," Gómez-Pinilla said. "BDNF
levels are reduced in the plasma of patients with major depression."

Smaller food portions with the appropriate nutrients seem to be
beneficial for the brain's molecules, such as BDNF, he said.

Gómez-Pinilla showed in 1995 that exercise can have an effect on the
brain by elevating levels of BDNF.

He noted that while some people have extremely good genes, most of us
are not so lucky and need a balanced diet, regular exercise and a good
night's sleep.

The study is available online at www.nature.com/nrn/journal/v9/n7/abs/nrn2421.html.

Source: University of California - Los Angeles

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