ADA:
Nuts May Lower Risk of Diabetes
Nut
consumption was inversely associated with risk of diabetes
New
data presented at the 62nd Scientific Sessions of the American
Diabetes Association suggest that eating nuts helps prevent the
development of diabetes and that zinc supplementation in obese,
insulin-resistant women improves insulin sensitivity, even in the
absence of zinc deficiency.
"Major
constituents of nuts (unsaturated fatty acids, magnesium and fiber)
have been inversely associated with risk of type 2 diabetes; however,
the overall effects of nut consumption on risk of type 2 diabetes are
not available," write Rui Jiang and colleagues from Brigham and
Women's Hospital in Boston. "Our results suggest that frequent
nut consumption is associated with lower risk of type 2 diabetes in
women."
In
this offshoot of the Nurses' Health Study, the authors analyzed data
from validated dietary questionnaires completed in 1980 by 83,818
women, aged 34 to 59 years, without a history of cardiovascular
disease, cancer, or diabetes. During 16 years of follow-up, 3,206
women developed type 2 diabetes.
After
adjustment for age, body mass index (BMI), smoking, physical activity,
family history of diabetes, alcohol, and total energy intake, nut
consumption was inversely associated with risk of diabetes. Compared
with women who almost never ate nuts, multivariate relative risk (RR)
among women who ate nuts less than once weekly was 0.93 (95%
confidence interval [CI], 0.86-1.01). RR was 0.84 (95% CI, 0.76-0.93)
among those who ate nuts one to four times weekly, and RR was 0.72
(95% CI, 0.60-0.88) among those who ate nuts more than five times
weekly (P<.0001 for trend).
The
protective effect of nuts did not vary after further controlling for
dietary factors, including intake of vegetables, fruits, and whole
grain, and a composite diet score composed of trans fat, cereal fiber,
glycemic load, marine omega-3 fatty acids, folate, and polyunsaturated
fat-to-saturated fat ratio.
"The
inverse association persisted within strata defined by levels of
family history of diabetes, body mass index, smoking, alcohol use,
physical activity, and dietary variables," the authors write.
In
a separate study by Dilina N. Marreiro and colleagues from
Universidade de Sao Paulo-SP in Brazil, zinc supplementation enhanced
insulin sensitivity in obese women who were not zinc-deficient.
In
this prospective, double-blind, clinical interventional study, 56
obese women with normal glucose tolerance were randomized to treatment
with zinc, 30 mg daily, or placebo for four weeks. At baseline, age
was 25 to 45 years, mean BMI was 36.2 ± 2.3 kg/m2, and
both groups were similar in clinical and laboratory parameters.
Insulin
resistance as measured by a homeostasis model assessment did not
change in the placebo group, but it decreased from 5.8 ± 2.6 to 4.3
± 1.7 (P<.05) in the zinc-supplemented group. Insulin
decreased from 28.8 ± 14.1 to 21.2 ± 8.1 mU/mL (P<.05) in
the zinc group but was unchanged in the placebo group.
"A
short time of zinc supplementation improved insulin sensitivity in
obese insulin [resistant] women without zinc deficiency," the
authors write. "Although the mechanism concerning the effect of
zinc supplementation is not completely understood, further studies are
recommended to address the possible role of zinc therapy in insulin
resistance states such as [diabetes]." ADA Annual
Meeting: Abstracts 1644-P, 569-P. June 16-17, 2002
