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Omega-3 fatty acids are
already prized by cardiologists for protecting the heart against the
inflammation that can lead to blocked arteries and for thwarting an irregular,
often fatal, heartbeat. There’s growing
evidence that these polyunsaturated fats may also be helpful in preventing
complications of diabetes and in soothing inflamed joints of arthritis.
Now Psychiatrists are also
taking a closer look. Omega-3s, dubbed
the “happy” fats in some quarters, are under investigation for treating
depression, bipolar disease, attention deficit hyperactivity disorder,
alcoholism, Alzheimer’s disease and even the so-called baby blues, or
postpartum depression. Earlier this
year, the American Psychiatric Association formed a committee to review the
findings to make treatment recommendations for the use of Omega-3s.
“Not only are the data
consistent in those areas, but they are very robust,” says Joseph R. Hibblen,
chief of the outpatient clinic at the
Laboratory of Membrane Biochemistry and Biophysics at the National Institute of
Alcohol Abuse and Alcoholism (NIAAA) in Bethesda.
And since there are few if
any side effects to eating foods rich in Omega-3 fatty acids, there’s little
downside to investigating these healthy fats – and a lot to be gained. Fish, and even fish oil dietary supplements,
are far cheaper than most prescription medications. Plus, there’s the hope that Omega-3s may help
bridge the treatment gap in mental disorders – up to 30 percent of people being
treated for depression, for example, find drugs inadequate in controlling their
symptoms.
The idea that Omega-3
fatty acids might help treat mental disorders dawned on Hibbeln in 1984 when he
was standing in an anatomy lab. “I had cut open the brain, and it just very
much struck me that it is mostly fat,” he says.
“The biochemistry of fat and lipids just seemed to be very unexplored in
psychiatric disorders and that seemed odd because there are many profound
neurological disorders that are known to be caused by lipid problems.”
It’s well recognized, for
example, that multiple sclerosis damages the fatty myelin sheathes of nerve
cells. Another neurological disorder,
Gaucher’s disease, results from the buildup of harmful fatty substances in
cells, and a whole class of neurological disorders called leukodystrophies are
caused by flawed development or maintenance of the fatty myelin in nerve cells.
The brain itself, is, in
fact, about 60% fat, giving new meaning to the term fathead. But unlike other adipose tissue throughout
the body, the brain’s fat is diverse, “as diverse as proteins in the body,”
notes Hibbeln.
Essential fatty acids are
fats that can’t be produced by the body but are required for good health. They play key roles in the structure of brain
cells and of the eye, particularly the retina.
They’re vital for each neuron’s membrane, both its outer protection and
its means of accessing key nutrients.
And it is these essential fats that regulate the growth of long tendrils
called axons that enable neurons to communicate with each other.
Oddly enough, while the
body can manufacture saturated fat, cholesterol and even some unsaturated fat –
it is incapable of producing two of the fatty acids that are most vital.
One is an Omega-3 fatty
acid called Alpha Linolenic Acid, which is found in fish, canola oil and
flaxseed. The other is an Omega-6 fatty
acid with the maddeningly similar name of Linolenic Acid, which is found in
soybean, safflower and corn oils, as well as in meat, poultry, fish and such
popular fare as processed foods.
Omega-3s and Omega-6s are close enough in chemical structure to be able
to compete for the same molecular machinery that allows entry into the brain.
(Omega-3 fatty acid molecules have three carbon atoms on one end; Omega-6 fatty
acids have six.)
That fact might simply
still be a little quirk of nature had not a huge shift occurred in diets during
the past century. In 1909, Americans got
most of their fat from free-range animals, which have higher levels of Omega-3s
than the chicken, beef and pork commonly eaten today. They also consumed about 0.02 pounds per year
of soybean oil – a number that increased gradually until about 1960, when
“soybean oil took over the U S food chain,“ says William Lands, a retired
biochemist with NIAAA. “It was like a
tsunami.”
By 1999, soybean oil – a
major ingredient in crackers, bread, salad dressings, baked goods and processed
food of all sorts – accounted for 20% of total calories consumed in the U S,
according to the U S Department of Agriculture.
Per capita consumption reached 25 pounds per year. “That means that
there has been a 1,000-fold increase in consumption of Omega-6 fatty acids:
over 100 years, Hibbeln says. “So we
have literally changed the composition of people’s bodies and their
brains. A very interesting question,
which we don’t know the answer to yet, is to what degree the dietary change has
changed overall behavior in our society.”
Flooding brains and bodies
with diet rich in Omega-6 fatty acids theoretically could give an unfair
advantage to these molecules, allowing them to block Omega-3s from getting inside
cells and replenishing stores in the brain and elsewhere in the body.
Intrigued by this
possibility, Hibbeln charted fish consumption worldwide and compared those
figures to rates of depression. In a paper published in 1998 in The Lancet,
he showed that nations with the highest fish consumption – Japan, Tiawan and
Korea – also had the lowest rates of depression. Nations with the lowest fish consumption –
New Zealand, Canada, West Germany, France and the U S – had the highest rates
of depression. “It becomes an
interesting picture across countries,” Hibbeln says.
Next, he took a look at
homicide, suicide and aggression rates and compared them to seafood
consumption. Similar patterns
emerged. Using World Health
Organization statistics, for example, Hibbeln found that men living in
land-locked Hungary, Bulgaria and Austria had the lowest fish consumption and
the highest rates of suicide, while their counterparts in Japan, Portugal, Hong
Kong, Korea and Norway ate the most fish and had the lowest rates of
suicide. Men living in the U S, Canada,
Italy, Australia and Sweden fell between the two extremes on both seafood
consumption and suicide rates.
Since then, Hibbeln has
examined patterns of postpartum depression, which provides a particularly interesting
window of opportunity for studying the psychological aspects of Omega-3 fatty
acids. That’s because during pregnancy,
mothers are the sole source of an Omega-3 fatty acid known as docosahenaenoic
acid (DHA) to the fetus. So key is this
substance to fetal brain development that the mother’s stores are depleted if
she doesn’t consume enough DHA in her diet.
In a 2002 study published in the
Journal of Affective Disorders, Hibbeln reported that “rates of postpartum
depression are 50 times higher in countries where women don’t eat fish,” he
says.
Of course, results from
such population studies – known as epidemiology – can at best show only
associations and trends, not cause and effect or a biological mechanism. To nail down any new scientific theory
requires both basic science and clinical trials.
Stoll put all these
elements together in a study of 30 people suffering from bipolar disorder, also
known as manic depression. During the
4-month study, which was published in 1999 in the Archives of General
Psychiatry, he randomly assigned participants to receive either fish oil
capsules containing Omega-3 fatty acids along with their standard treatment of
a placebo of olive oil plus the standard treatment. The study found that
Omega-3s significantly lengthened the period of remission for those who
received them.
Since then, a handful of
other small, short-term studies have also found benefits to Omega-3s. In England, Malcom Peet and his colleagues at
the Swallownest Court Hospital in Sheffield gave another type of Omega-3 –
eicosapentaenoic acid (EPA) – in varying doses to people with ongoing
depression that was not well controlled with antidepressants. Peet found in this 12-week study that one
gram per day of EPA was significantly better than placebo in improving
mood. (Both groups also received
standard antidepressant medication.) Other studies found that Omega-3s were
helpful in controlling postpartum depression, impulsivity and even antisocial
behavior in prisoners.
To Stoll and other
proponents of the benefits of Omega-3 fatty acids in treating mental disorders,
the results have been a kind of vindication. “We were laughed at 5 years ago
and teased by our colleagues,” says Stoll, an associate professor of psychiatry
at Harvard Medical School. “Now this is
in textbooks.”
But the story is still
unfolding. Exactly how Omega-3s may work
is not yet known. Scientists know that
these fats break down into EPA and DHA in the body, while Omega-6 fatty acids
break down to a substance called arachidonic acid. Nothing is static in the body. So these products just continue a cascade of
other biochemical reactions that produce more substances – chemicals that act
like a thermostat to raise and lower production of other key substances that in
turn control blood clot formation, immune responses, bone health, smooth
muscles and so on and so on.
In the meantime, research
continues to point to the cardiovascular benefits of eating a diet rich in
Omega-3 fatty acids. Some of the latest
findings, published in the journal Circulation, found that men who ate at least
two servings of fish per week had lower heart rates, meaning their heartbeats
were stronger and more efficient, beating fewer times per minute than men who
ate fish less than once per week. And
the twice-weekly fish eaters also had a significantly reduced risk of heart
disease compared with those who ate fish less than once per week.
Some of the Omega-3
researchers are so convinced of the benefits of these essential fats that they
are making sure their families eat foods rich in them.
Harvard’s Stoll is so
convinced of the benefits of Omega-3s that he jokes he nearly force-feeds food
rich in Omega-3s to his three children.
His two older kids also take a daily fish oil supplement made by a
company that Stoll’s wife – also a psychiatrist – formed after seeing his
data. His youngest child, who doesn’t
like fish and can’t swallow pills yet, dines on flax-meal pancakes, on
flax-meal with honey and walnuts and on flax, wild game and other foods laced
with ground flaxseed.
As Stoll says, “Anything
good for the heart seems to be good for the brain.”
