 |
|
|
COULD ALTERED LEVELS OF FATTY ACIDS MAKE US MORE AGGRESSIVE?
Omega-3 fatty acids, which are not manufactured by the body
and must be obtained from the diet, are essential to brain
development and function. Modern Western diets contain a lower
amount of these fats than the diets of earlier generations, while
containing a higher level of omega-6 fatty acids such as linoleic
acid. Growing research tentatively links this dietary alteration to
increases in depression, learning disabilities, and attention deficit
disorder
(see related article, Crime Times, 1999, Vol. 5, No. 1, Page 1),
and now clinical and epidemiological studies also hint at a link to
increases in aggressive or violent behavior.
Joseph Hibbeln et al. have conducted a series of studies
examining the effects of omega-3 and omega-6 fatty acid levels on
aggression, hostility, and rates of homicide. In one study, the
researchers analyzed economic measures of omega-6
consumption across time and countries to see if these were
related to trends in homicide rates. They report finding evidence of
"a striking correlation between greater apparent consumption of
linoleic acid from seed oils and greater risk of homicide mortality
across time, from 1961 to 2000, among five Western countries [the
United States, the United Kingdom, Australia, Canada, and
Argentina]." Hibbeln et al. say that this finding, and earlier
research by the same authors showing that greater intakes of
omega-3 rich seafood correlate with lower rates of homicide
mortality across 36 countries, "are consistent with animal studies
and controlled intervention trials in humans
[Gesch et al., Crime Times, Volume 8, Number 3, 2002, page 1]
that reported decreased measures of aggression or violence by
increasing intakes of long chain omega-3 fatty acids relative to
omega-6 intake."
Hibbeln et al. say, "One mechanism that may link excessive
linoleic acid intake or deficient EPA and DHA status is a deficit in
serotonergic neurotransmission in the frontal cortex, which has
been repeatedly implicated in the pathophysiology of lifelong
impulsive and violent behaviors." They cite animal research
showing that dietary deficiencies of omega-3 fatty acids during
fetal development and early postnatal life are linked to residual
deficits in serotonergic neurotransmission.
The researchers conclude that while multiple factors contribute
to aggression and violence across cultures, and the possible
associations between omega-3 and omega-6 fatty acids and
homicide rates need to be further investigated,
"dietary
interventions that reduce linoleate intake and improve the tissue
status of omega-3 fatty acids and other basic nutrients can
potentially become relatively cost-effective measures for reducing
the pandemic of violence in Western societies, just as dietary
interventions are reducing cardiovascular mortality."
In a separate study, Hibbeln and colleagues note that elevated
levels of corticotrophin-releasing hormone (CRH) in the cortical-
hippocampal-amygdala pathway increase fear and anxiety,
emotions that play a strong role in violent behavior. Levels of two
prostaglandins that increase CRH activity in this pathway are
reduced by omega-3 fatty acids. Thus, the researchers theorize, a
diet low in omega-3 fatty acids could lead, indirectly, to increased
expression of CRH and thus to elevated levels of violence-
provoking fear and anxiety.
To test this theory, the researchers measured plasma levels of
fatty acids in 21 perpetrators of domestic violence. They found that
lower levels of DHA predicted greater cerebrospinal fluid levels of
CRH.
"Randomized, placebo-controlled trials are needed to determine
if supplementation with DHA and EPA can decrease elevated
levels of CRH and improve behavioral outcomes among subjects
with aggressive and violent behaviors," they say.
Hibbeln and colleagues note that additional findings support the
link between low omega-3 fatty acids and behavioral disorders.
These findings include:
- Another study by Hibbeln et al. showing an association
between high consumption of DHA and seafood and reduced
levels of hostility in young adults
(see related article, Crime Times, 2004, Vol. 10, No. 2, Page 3).
- A study by M. C. Zanarini and colleagues showing that
supplementation with EPA reduced aggressive behavior as well as
the severity of depressive symptoms in women with borderline
personality disorder.
- A study by Tomohito Hamazaki et al., who found that DHA
supplements prevented stress-linked increases in aggression in
students
(see related article, Crime Times, 1999, Vol. 5, No. 1, Page1).
-----
"Increasing homicide rates and linoleic acid consumption
among five Western countries, 1961-2000," Joseph R. Hibbeln,
Levi R. C. Nieminen, and William E. M. Lands, Lipids, Vol. 39,
No. 12, 2004, 1207-13. Address: Joseph R. Hibbeln, Section
on Nutritional Neurochemistry, LMBB, NIAAA, 31 Center Drive,
Building 31/1B 58, Bethesda, MD 20892,
jhibbeln@mail.nih.gov.
-- and --
"Omega-3 status and cerebrospinal fluid corticotrophin
releasing hormone in perpetrators of domestic violence," Joseph
R. Hibbeln, Garth Bissette, John C. Umhau, and David T. George,
Biological Psychiatry, Vol. 56, 2004, 895-97. (See address
above.)
|
|
