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    Trans-Palmitoleic Acid In Dairy And Meat Trans Fats May Cut Diabetes Risk
    By News Staff | December 20th 2010 06:34 PM | 3 comments | Print | E-mail | Track Comments
    Researchers say they 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, butter and meat but is not produced by the body and so only comes from the diet.

    The report explains 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 the trans-palmitoleic acid discovery means once again it's better to avoid fad exclusions and diets and simply have a balanced diet in moderation.

    The 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 Dariush Mozaffarian, associate professor in the Department of Epidemiology at Harvard School of Public Health (HSPH) and 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.

    Gökhan S. Hotamisligil, J.S. Simmons Professor of Genetics and Metabolism and chair of the Department of Genetics and Complex Diseases at HSPH and 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.

    Citation: 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: A Cohort Study', Ann Intern Med December 21, 2010 153:790-799

    Comments

    I think butter can be part of healthy diet, it is a good idea. but This study does not prove that dairy fat prevents diabetes.

    Hank
    Neither the study nor the article claimed it did.   People tend to get confused about risk factors and what they mean despite their prevalence in the cultural conversation for the last decade.
    rholley
    This sounds like a trans fat.  So up goes I a-wiki-chasing, and find:

    Under Palmitoleic acid (C16 cis):
    High density lipoprotein (HDL, "good cholesterol") was significantly lower with palmitoleic than with palmitic acid. ... Palmitoleic acid behaves like a saturated and not a monounsaturated fatty acid in its effect on LDL cholesterol.
    This would appear to suggest that with 16 carbons, trans fat good, cis fat bad(ish).

    On the contrary, under Oleic acid (C18 cis), one finds no mention of cholesterol, but under Health Effects:
    Oleic acid may hinder the progression of ALD, or adrenoleukodystrophy, a fatal disease that affects the brain and adrenal glands.

    Oleic acid may help boost memory.

    Oleic and monounsaturated fatty acid levels in the membranes of red blood cells have been associated with increased risk of breast cancer.

    Oleic acid may be responsible for the hypotensive (blood pressure reducing) effects of olive oil.
    while the 18 C trans acid has a different name, Elaidic Acid.  And it appears here that trans fat bad, cis fat good.

    Is this complicated enough?  Good, let’s add one more layer, this time from Omega-9 fatty acid.
    Unlike n−3 and n−6 fatty acids, n−9 fatty acids are not classed as essential fatty acids (EFA). This is both because they can be created by the human body from unsaturated fat, and are therefore not essential in the diet, and because the lack of an n−6 double bond keeps them from participating in the reactions that form the eicosanoids.
    So is it the trans fats formed in the n-3 and -6 position that are so bad?

    Maybe I’ll rest here awhile, but stick to my mixed diet.
    Robert H. Olley / Quondam Physics Department / University of Reading / England