MONDAY, Dec. 20 (HealthDay News) -- New research suggests that
whole-fat dairy products -- generally shunned by health experts --
contain a fatty acid that may lower the risk of type 2
The fatty acid is called trans-palmitoleic acid, according to
the study in the Dec. 21 issue of the
Annals of Internal Medicine, and people with the highest blood levels of this fatty acid reduce their odds of diabetes by 62 percent compared to those with the lowest blood levels of it.
In addition, "people who had higher levels of this fatty acid
had better cholesterol and triglyceride levels, lower insulin
resistance and lower levels of inflammatory markers," said study
author Dr. Dariush Mozaffarian, co-director of the program in
cardiovascular epidemiology at Brigham and Women's Hospital and
Harvard School of Public Health.
Circulating palmitoleic acid is found naturally in the human
body. It's also found in small quantities in dairy foods. When it's
found in sources outside the human body, it's referred to as
trans-palmitoleic acid. Whole milk has more trans-palmitoleic acid
than 2 percent milk, and 2 percent milk has more of this fatty acid
than does skim milk.
"The amount of trans-palmitoleic acid is proportional to the amount of dairy fat," said Mozaffarian.
Animal studies of the naturally occurring palmitoleic acid have
previously shown that it can protect against insulin resistance and
diabetes, said Mozaffarian. In humans, research has suggested that
greater dairy consumption is associated with a lower diabetes risk.
However, the reason for this association hasn't been clear.
To assess whether this overlooked and relatively rare fatty acid
might contribute to dairy's apparent protective effect, the
researchers reviewed data from over 3,700 adults enrolled in the
Cardiovascular Health Study.
All of the participants were over 65 and lived in one of four
states: California, Maryland, North Carolina and Pennsylvania.
Blood samples were analyzed for the presence of
trans-palmitoleic acid, as well as cholesterol, triglycerides,
C-reactive protein and glucose levels. Participants also provided
information on their usual diets.
People with higher levels of trans-palmitoleic acid had slightly
less fat on their bodies, according to the study. They also had
higher "good" cholesterol levels and lower overall cholesterol
levels. They had lower levels of C-reactive protein, a marker of
inflammation. And they showed evidence of lower levels of insulin
resistance, according to the study.
Most significantly, however, those with higher trans-palmitoleic
acid levels had lower odds of developing type 2 diabetes. Those
with the highest levels of trans-palmitoleic acid reduced their
odds of type 2 diabetes by nearly two-thirds.
Mozaffarian said it's difficult to know exactly how many
servings of dairy it would take to get to the highest levels of
trans-palmitoleic acid, but said it was likely three to five
servings a day, depending on the type of dairy consumed.
However, he said, it's too soon to make
any dietary recommendations based on the results of just this
"This study confirms that something about dairy is linked very strongly to a lower risk of diabetes, but no single study should be enough to change guidelines," he said, adding that he hopes this study will spur more research.
Dr. Sue Kirkman, senior vice president of medical affairs and
community information for the American Diabetes Association, agreed
that it's too soon to change dietary guidelines, but said the
findings do suggest "that things may be more complicated than we
might simplistically think. It looks like we can't say all
trans-fats are bad, as this one was associated with decreases in
diabetes, insulin resistance and C-reactive protein levels."
Dr. Joel Zonszein, director of the Clinical Diabetes Center at
Montefiore Medical Center in New York City, concurred, noting,
"this was a very nice, and very robust, association. Maybe whole
milk isn't so bad, but I don't think there's enough evidence to
show that we should start drinking whole milk. We need to
understand the mechanism behind this association. Dietary changes
in this country tend to be to extremes, but this study should not
be used to make changes in the diet; it's just an observation right
Learn more about what you can do to help prevent diabetes from
U.S. Centers for Disease Control and
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