DALLAS, April 1 - Eating fish regularly reduced the risk of heart
diabetic women by as much as 64 percent, according to study reported in
today's rapid access issue of Circulation: Journal of the American
"We found that women with type 2 diabetes who ate more fish had
significantly lower risk of coronary heart disease and total death than
those who rarely ate fish," says Frank B. Hu, M.D., lead author and
associate professor of nutrition and epidemiology at the Harvard School
Public Health in Boston. "Previous studies have found that fish
reduces risk of heart disease in a largely healthy population. This is
first study to look at the relationship among diabetic patients, who
very high risk of heart disease."
The American Heart Association recommends that adults, except pregnant
women, eat two servings of fish a week. For those with, or at high risk
cardiovascular disease (CVD), supplementing fish in the diet with fish
capsules may be advisable in consultation with a physician.
Also known as fish oil, omega-3 fatty acids from fish have been shown
reduce the risk of irregular heartbeats that can lead to sudden death,
decrease blood triglyceride levels, improve the functions of blood
and reduce blood clot formation. These effects are particularly
for reducing risk for CVD among diabetics.
Even so, little data were available to confirm that diabetics who ate
would receive the same benefits as people without diabetes who ate
says. In addition, there was concern that fish oil might worsen control
blood sugar (glucose) among diabetic patients.
Hu and colleagues analyzed data from women with diabetes participating
the Nurses' Health Study, which was established in 1976 when 121,700
registered nurses completed a questionnaire about their medical history
lifestyle. Every two years, follow-up questionnaires have been mailed
update information on risk factors and any new health problems. The
study includes 5,103 women who reported physician-diagnosed type 2
on any questionnaire from 1976-94. Women with a history of heart
stroke or cancer reported on the 1980 questionnaire (when diet was
assessed) or before were excluded.
The women were divided into five categories according to how often they
fish: less than once a month, one to three times a month, once a week,
to four times a week, and five or more times a week.
Between 1980-96, the researchers documented 362 cases of heart disease
heart-related deaths and 221 nonfatal heart attacks). There were 468
overall. Diabetic women who ate fish at least once a month were older,
slightly heavier, typically didn't smoke, tended to have hypertension
high cholesterol, and took multivitamin and vitamin E supplements.
ate more fish also ate more fruits and vegetables but ate less red and
Compared with diabetic women who seldom ate fish (less than once a
the risk of developing heart disease was reduced on average by 30
those who ate fish one to three times a month, 40 percent for those who
it once a week, 36 percent in those who ate fish two to four times a
and 64 percent in those who ate fish five or more times a week. Higher
consumption was also associated with a significantly lower death rate.
Hu says that the association between higher fish consumption in
women and better heart health can also be extended to diabetic men
similar findings in studies of healthier men and women.
"One limitation of this study is that it is not a randomized clinical
trial," Hu says. "Thus, the benefits we observed for fish may be due to
other dietary and lifestyle factors related to fish intake." Even so,
says their findings are solid because of their "careful adjustment for
important cardiovascular risk factors.
"Regular fish consumption should be considered as part of a healthy
diabetes management," Hu says. "For individual patients, at least two
servings of fish per week is recommended."
Fatty fish such as mackerel, lake trout, herring, sardines, albacore
and salmon are high in omega-3 fatty acids.
An accompanying editorial by Scott M. Grundy, M.D., director of the
for Human Nutrition at the University of Texas Southwestern Medical
at Dallas, provides a review of the current status of research on
fatty acids in fish, plants and supplements.
Grundy says Hu's research supports previous prospective epidemiological
studies that found omega-3 fatty acids offer protection against CVD.
However, he urges that clinical trials of omega-3 fatty acids after a
attack be conducted to determine if they can reduce coronary deaths in
Hu's co-authors are Eunyoung Cho, Sc.D.; Kathryn M. Rexrode, M.D.;
M. Albert, M.D.; and JoAnn E. Manson, M.D. The study was partly funded
the National Institutes of Health and the American Heart Association.