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http://www.sciencedaily.com/releases/2010/12/
101220200000.htm
Component in Common Dairy Foods May Cut Diabetes Risk, Study Suggests
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Dairy products. Scientists have identified a natural substance in dairy fat
that may substantially reduce the risk of type 2 diabetes. The compound,
trans-palmitoleic acid, is a fatty acid found in milk, cheese, yogurt, and
butter. It is not produced by the body and so only comes from the diet.
(Credit: iStockphoto/Olivier Tuff)
ScienceDaily (Dec. 20, 2010) Scientists at the Harvard School of Public
Health (HSPH) and collaborators from other institutions have identified a
natural substance in dairy fat that may substantially reduce the risk of type 2
diabetes. The compound, trans-palmitoleic acid, is a fatty acid found in milk,
cheese, yogurt, and butter. It is not produced by the body and so only comes
from the diet.
Reporting in the December 21, 2010, issue of Annals of Internal Medicine,
investigators led by Dariush Mozaffarian, associate professor in the Department
of Epidemiology at HSPH and Division of Cardiovascular Medicine, Brigham and
Women's Hospital and Harvard Medical School, and Gökhan S. Hotamisligil, J.S.
Simmons Professor of Genetics and Metabolism and chair of the Department of
Genetics and Complex Diseases at HSPH, explain that trans-palmitoleic acid may
underlie epidemiological evidence in recent years that diets rich in dairy
foods are linked to lower risk of type 2 diabetes and related metabolic
abnormalities. Health experts generally advise reducing full-fat dairy
products, but trans-palmitoleic acid is found in dairy fat.
The HSPH researchers examined 3,736 participants in the National Heart, Lung,
and Blood Institute-funded Cardiovascular Health Study, who have been followed
for 20 years in an observational study to evaluate risk factors for
cardiovascular diseases in older adults. Metabolic risk factors such as blood
glucose and insulin levels, and also levels of circulating blood fatty acids,
including trans-palmitoleic acid, were measured using stored blood samples in
1992, and participants were followed for development of type 2 diabetes.
At baseline, higher circulating levels of trans-palmitoleic acid were
associated with healthier levels of blood cholesterol, inflammatory markers,
insulin levels, and insulin sensitivity, after adjustment for other risk
factors. During follow-up, individuals with higher circulating levels of
trans-palmitoleic acid had a much lower risk of developing diabetes, with about
a 60% lower risk among participants in the highest quintile (fifth) of
trans-palmitoleic acid levels, compared to individuals in the lowest quintile.
"This type of observational finding requires confirmation in additional
observational studies and controlled trials, but the magnitude of this
association is striking," said Mozaffarian, lead author of the study. "This
represents an almost three-fold difference in risk of developing diabetes among
individuals with the highest blood levels of this fatty acid."
In contrast to the types of industrially produced trans fats found in partially
hydrogenated vegetable oils, which have been linked to higher risk of heart
disease, trans-palmitoleic acid is almost exclusively found in
naturally-occurring dairy and meat trans fats, which in prior studies have not
been linked to higher heart disease risk.
"There has been no clear biologic explanation for the lower risk of diabetes
seen with higher dairy consumption in prior studies. This is the first time
that the relationship of trans-palmitoleic acid with diabetes risk has been
evaluated," said Mozaffarian. "We wonder whether this naturally occurring trans
fatty acid in dairy fats may partly mimic the normal biologic role of its cis
counterpart, cis-palmitoleic acid, a fatty acid that is produced in the body.
In animal experiments, cis-palmitoleic acid protects against diabetes."
"Unfortunately, with modern diets, synthesis of cis-palmitoleic acid is now
driven by high amounts of carbohydrate and calories in the diet, which might
limit its normal protective function. We wonder whether trans-palmitoleic acid
may be stepping in as a "pinch hitter" for at least some of the functions of
cis-palmitoleic acid," said Mozaffarian.
Hotamisligil, the study's senior author, also emphasized the magnitude of the
risk reduction. "This is an extremely strong protective effect, stronger than
other things we know can be beneficial against diabetes. The next step is to
move forward with an intervention trial to see if there is therapeutic value in
people."
Because trans-palmitoleic acid, also known as trans-palmitoleate, is a natural
compound, Hotamisligil said that conducting clinical trials should be possible.
"This study represents the power of interdisciplinary work bridging basic
science with population studies to realize exciting translational
possibilities," he said.
Support for the study was provided by the National Heart, Lung, and Blood
Institute and National Institute of Diabetes and Digestive and Kidney Diseases
of the National Institutes of Health and the National Institutes of Health
Office of Dietary Supplements and National Institute of Neurological Disorders
and Stroke. A subset of additional fatty acid measurements were supported by a
Searle Scholar Award.
Disclaimer: This article is not intended to provide medical advice, diagnosis
or treatment. Views expressed here do not necessarily reflect those of
ScienceDaily or its staff.
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Story Source:
The above story is reprinted (with editorial adaptations by ScienceDaily
staff) from materials provided by Harvard School of Public Health, via
EurekAlert!, a service of AAAS.
Journal Reference:
1. Dariush Mozaffarian, Haiming Cao, Irena B. King, Rozenn N. Lemaitre,
Xiaoling Song, David S. Siscovick, and Gökhan S. Hotamisligil.
Trans-Palmitoleic Acid, Metabolic Risk Factors, and New-Onset Diabetes in U.S.
Adults. Annals of Internal Medicine, December 21, 2010 [link]
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Harvard School of Public Health (2010, December 20). Component in common dairy
foods may cut diabetes risk, study suggests. ScienceDaily. Retrieved December
23, 2010, from http://www.sciencedaily.com /releases/2010/12/101220200000.htm
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