A diet rich in omega-3 fatty acids
cuts in half kids' risk of developing type I diabetes,
according to a new study in the September 26 JAMA.
"This is the first study to show this type of association
with childhood diet," says Jill Norris, PhD, lead author
and epidemiologist at the University of Colorado at
Denver. "It provides exciting evidence that it may be
feasible to have a nutritional intervention against
the disease."
Since type I diabetes is often
inherited, researchers looked at high-risk kids —
those who had a high-risk genotype or had a diabetic
parent or sibling. They found that children who ate
fish, nuts or other omega-3 fatty acid sources were
55% less likely to become diabetic.
EARLY
CATCH
In type I diabetes, the body makes antibodies to attack
its own beta-cells, the insulin-producers in the pancreas.
It often hits patients in early childhood or adolescence.
But before blood sugar runs high and diabetes is diagnosed,
there's a phase that can last from months to years when
those auto-antibodies accumulate in the blood. This
stage is known as islet autoimmunity (IA). "IA is very
predictive of the disease," explains Dr Norris.
Researchers ran blood tests on
1,770 high-risk children, once a year between 1994 and
2006, to check IA levels. Parents were enlisted to monitor
their kids' diets and report their omega-3 fatty acid
intake, also on an annual basis, through food frequency
questionnaires. The more kids consumed omega-3s, the
less they developed IA, the study found.
But since parents may not be the
most accurate way to get information, researchers decided
to measure omega-3 status separately, says Dr Norris.
So they looked at the omega-3 fatty acids in the red
blood cell membranes of 244 kids.
Cell membranes contain chains of
fatty acids that help them keep their structure and
fluidity. "The more you eat omega-3 fatty acids, the
more they get incorporated into the cell membranes,"
explains Dr Norris. The children with the highest omega-3s
had a 37% reduced chance of becoming diabetic. "It's
a nice corroboration with our dietary report," says
Dr Norris.
Fifty-eight kids in the study developed
IA. Of those, 45 went on to become diabetic. These kids
were all in the lowest omega-3 intake group.
O-MEGA
PREVENTION
Omega-3 fatty acids are commonly found in fish, soybeans
and walnuts among other foods. Animal studies had long
suggested these molecules played a role in preventing
diabetes. A Norwegian study showed that kids with diabetes
were less likely to have been given cod liver oil as
infants — but cod liver oil contains both fatty
acids and Vitamin D.
The JAMA study is the first
human study to establish a clear connection between
omega-3 FAs and diabetes, say the authors. What's more,
the risk reduction applied even when the omega-3 came
from plants and legumes, not just fish. Exactly how
they prevent it is still a mystery, admits Dr Norris.
"But we think it's due to anti-inflammatory properties
in the omega-3 fatty acids." An inflammatory response
is part of the early stages of diabetes.
It's still not known if the effect
of omega-3 on IA is lasting, or if at-risk kids would
have to keep their fatty acid intake high all their
lives. So it's still too early to start recommending
fish oil supplements, says Dr Norris. "But evidence
is out there to pursue the exact mechanism of this process
and feasibility of a prevention," she adds.
Nearly 200,000 Canadians suffer
from type I diabetes. It is the third most common chronic
disease in kids and cuts their life expectancy by as
much as 15 years. Insulin injections help control blood
sugar levels in patients, but nothing, until now, was
thought capable of preventing the disease.
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