It's good news that we are living longer, but bad news
that the longer we live, the better our odds of developing
late-onset Alzheimer's disease.
Many Alzheimer's researchers have
long touted fish oil, by pill or diet, as an accessible
and inexpensive "weapon" that may delay or prevent
this debilitating disease. Now, UCLA scientists have confirmed
that fish oil is indeed a deterrent against Alzheimer's,
and they have identified the reasons why.
Greg Cole, professor of medicine and neurology at the
David Geffen School of Medicine at UCLA and associate
director of UCLA's Alzheimer Disease Research Center,
and his colleagues report that the omega-3 fatty acid
docosahexaenoic acid (DHA) found in fish oil increases
the production of LR11, a protein that is found at reduced
levels in Alzheimer's patients and which is known to destroy
the protein that forms the "plaques" associated
with the disease.
The plaques are deposits of a protein called beta amyloid
that is thought to be toxic to neurons in the brain, leading
to Alzheimer's. Since having high levels of LR11 prevents
the toxic plaques from being made, low levels in patients
are believed to be a factor in causing the disease.
Alzheimer's is a debilitating neurodegenerative disease
that causes memory loss, dementia, personality change
and ultimately death. The national Alzheimer's Association
estimates that 5.1 million Americans are currently afflicted
with the disease and predicts that the number may increase
to between 11 million and 16 million people by the year
The researchers examined the effects of fish oil, or
its component DHA, in multiple biological systems and
administered the oil or fatty acid by diet and by adding
it directly to neurons grown in the laboratory.
"We found that even low doses of DHA increased the
levels of LR11 in rat neurons, while dietary DHA increased
LR11 in brains of rats or older mice that had been genetically
altered to develop Alzheimer's disease," said Cole,
who is also associate director of the Geriatric Research
Center at the Veterans Affairs Medical Center.
To show that the benefits of DHA were not limited to
nonhuman animal cells, the researchers also confirmed
a direct impact of DHA on human neuronal cells in culture
as well. Thus, high levels of DHA leading to abundant
LR11 seem to protect against Alzheimer's, Cole said, while
low LR11 levels lead to formation of the amyloid plaques.
Fish oil and its key ingredient, omega-3 fatty acids
(found in fatty fish like salmon), have been a mainstay
of alternative health practitioners for years and have
been endorsed by the American Heart Association to reduce
the risk of cardiovascular disease.
Fatty acids like DHA are considered "essential"
fatty acids because the body cannot make them from other
sources and must obtain them through diet. Years of research
have shown that DHA is the most abundant essential fatty
acid in the brain, Cole said, and that it is critical
to fetal and infant brain development. Studies have also
linked low levels of DHA in the brain to cognitive impairment
and have shown that lower levels may increase oxidative
stress in the brains of Alzheimer's patients.
Based on the positive results, the National Institutes
of Health is currently conducting a large-scale clinical
trial with DHA in patients with established Alzheimer's
disease. For those patients, Cole said, it may be too
late in the disease's progression for DHA to have much
effect. But he is hopeful that the NIH will conduct a
large-scale prevention clinical trial using fish oil at
the earliest stages of the disease -- particularly because
it is unlikely that a pharmaceutical company will do so,
since fish oil in pill form is readily available and inexpensive.
Still to be determined, he said, "is what the optimal
dose should be. It could be that a smaller amount might
be helpful, especially in a place like the south of France,
where people are already on a Mediterranean diet."
Here in the United States, though, where fish consumption
is not very high, the dose may need to be higher.
"There's a deficiency of DHA to begin with,"
Cole said, "and this may contribute to the low LR11
seen in many Alzheimer's patients."