Omega-3s tied to lower risk of rheumatoid arthritis
Women who have diets high in omega-3
fatty acids derived from fish are less likely
to develop rheumatoid arthritis than
those who skimp on fish, new research
suggests.
Researchers surveyed Swedish women
about their diets and found over the
course of more than seven years, long-
term consumption of more than one
serving of fatty fish each week was tied to
a lower risk of developing the condition.
"This study is the first to attribute the
protective effect of fish against
rheumatoid arthritis to its content of
omega-3 fatty acids," Daniela Di Giuseppe,
a doctoral student at the Karolinska
Institute in Stockholm and lead author of
the study, told Reuters Health in an email.
Rheumatoid arthritis is an autoimmune
disease that causes joint inflammation,
deformities and disability. People with the
condition also have a higher risk of heart
disease, some infections, anxiety,
depression and blood cancers like
leukemia.
According to the American College of
Rheumatology, between 0.5 and 1
percent of the U.S. population has
rheumatoid arthritis. Women are two to
three times more likely than men to
develop the disease, which most
commonly starts affecting people in their
60s.
Di Giuseppe and her colleagues followed
over 32,000 women born between 1914
and 1948 who were part of the Swedish
Mammography Cohort. Information about
fish consumption was gathered from diet
questionnaires sent to women in 1987
and 1997.
National registries were used to identify
new diagnoses of rheumatoid arthritis
between 2003 and 2010.
The researchers separated women into
five groups based on the amount of fish-
based omega-3 fatty acids in their diet,
ranging from 0.21 grams or less per day
to at least half a gram daily.
Eating 0.21 grams per day of omega-3
fatty acids equates to about one serving
per week of salmon and other fatty fish,
or four servings per week of lean fish
such as cod.
During follow-up, 205 women developed
rheumatoid arthritis, the researchers
reported in Annals of the Rheumatic
Diseases.
Long-term consumption of any fish at
least once per week, compared to less
than one weekly serving, was tied to a 29
percent lower risk of rheumatoid arthritis.
However, that finding could have been
due to chance, the researchers found.
Women who reported getting more than
0.21 grams of omega-3 fatty acids derived
from fish per day both in 1987 and 1997
had a 52 percent decreased risk of
developing the disease, compared to
those who ate the least.
The researchers found a threshold effect,
suggesting more omega-3s may not always
be better. Below 0.35 grams per day, the
risk of rheumatoid arthritis increased, but
above it, the benefits seemed to taper off.
The results are consistent with other
studies that have found threshold effects,
and with recommendations from the U.S.
Department of Agriculture and the
Department of Health and Human
Services, which advise eating at least two
servings of fish per week.
The researchers concluded that
"moderate consumption of fish is
sufficient to reduce risk of diseases."
Genes and lifestyle may both play a role
in rheumatoid arthritis. Dr. Simon
Helfgott, a rheumatoid arthritis researcher
at Harvard Medical School in Boston, said
the top three things people can do to
prevent the disease are not smoke, avoid
gum disease by having good oral hygiene
and improve their diet.
"When we say diet there's really only one
influence that seems to affect rheumatoid
arthritis and that's fish consumption,"
Helfgott, who was not involved in the new
research, said.
Omega-3 fatty acids are used by the body
to make molecules that help regulate
inflammation, known as eicosanoids. The
current thinking is that eicosanoids
derived from essential fatty acids in meat
promote more inflammation than those
from omega-3 fatty acids in fish,
researchers said.
"This study lends credence to a strongly
considered hypothesis in rheumatology
circles, which is that we might be able to
intervene in preventing rheumatoid
arthritis in some individuals," Helfgott
said.
