The fish oil compound DHA (docosahexaenoic acid) has long been known to have anti-inflammatory effects, and now researchers have gained a better understanding of why.


Published in The FASEB Journal, a new study shows that DHA seems to be a vital player in the production of molecules called maresins[1] , which are able to turn "off" inflammation.


"We've known for a long time that DHA tames inflammation, now, we learn exactly how DHA works: via new substances called maresins," Dr. Gerald Weissmann, M.D., who is the editor in chief of The FASEB Journal[2] , where the study was published, said in a statement. "We encounter inflammation almost daily, but our body has ways of turning it off. This is an important step toward understanding exactly [how] this happens. You're likely to be hearing a lot more about maresins if, or when, new therapies arise from this discovery."


Inflammation[3] is not all bad -- it's our bodies' natural response to infection and injury. But when inflammation becomes chronic[4] -- meaning our body is always mounting a defense and won't turn off -- that's when health risks arise. Chronic inflammation has been linked with ills ranging from cancer to diabetes to Alzheimer's, U.S. News reported.


For the new study, researchers from Harvard Medical School, the University of Southern California and the Karolinska Institutet found that a kind of white blood cell called the macrophage converts DHA to make maresins. Maresins then are able to prompt macrophages to turn from an inflammation-causing type to a non-inflammation-causing type.


Earlier this year, research in mice showed that DHA could also boost the body's immune response[5] by increasing activity of the B cell, which is a kind of white blood cell. Those findings, published in the Journal of Leukocyte Biology, were conducted in mice.



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  • Trans Fats


    While processed foods are slowly but surely cutting back on trans fat, it's still smart to investigate labels for hydrogenated or partially hydrogenated oils and leave those packages on the shelf. <a href="http://www.ncbi.nlm.nih.gov/pubmed/15051604">Trans fats can induce inflammation</a> by <a href="http://www.mayoclinic.com/health/trans-fat/CL00032/NSECTIONGROUP=2">damaging the cells in the lining of blood vessels</a>, according to the Mayo Clinic, part of the reason many companies are limiting use to begin with, says Sandquist. Although small amounts of trans fats do occur naturally in certain foods, the majority are manmade and therefore difficult for the body to process, Black explains. "Our body doesn't have a natural mechanism for breaking it down," which can trigger an inflammatory response," she says.




  • Sugar


    "Trans fats should be old news, sugar should be new news," says Black, calling it the food item we most ignore when it comes to our health (although, <a href="http://www.huffingtonpost.com/2013/02/28/sugar-type-2-diabetes-rates-robert-lustig_n_2750965.html">that may be changing</a>). "I don't think our body was meant to break down as much sugar as we consume," she says. Too much sugar can alert the body to <a href="http://www.cnn.com/2012/07/20/health/food-cause-pain-daniluk">send out extra immunity messengers</a>, called cytokines, Daniluk wrote for CNN.




  • White Bread


    White breads and pastas break down quickly into sugar, and in turn lead to inflammation. In a 2010 study, researchers found that a diet high in <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2821887/">refined grains led to a greater concentration of a certain inflammation marker</a> in the blood, while a diet high in <em>whole</em> grains resulted in a lower concentration of two different inflammation markers. White breads are a telling example of inflammatory foods, says Daniluk. "They've been refined in a way that goes against nature, goes against what our bodies need," she says. Processing away the nutritional properties of whole grains leaves "fast-digesting carbohydrates beyond empty calories," she says, which irritate our bodies.




  • Cheeseburgers


    <a href="http://content.onlinejacc.org/article.aspx?articleid=1137827">Animal fats have been linked to inflammation</a> in a number of studies. One tracked how our beneficial <a href="http://blogs.scientificamerican.com/observations/2012/06/13/saturated-fats-change-gut-bacteria-and-may-raise-risk-for-inflammatory-bowel-disease/">gut bacteria change after eating saturated fats</a> and found that "as the balance of species shift, it can trigger an immune response that results in inflammation and tissue damage," Scientific American reported. Saturated fats also contain a compound the body uses to <em>create</em> inflammation naturally called <a href="http://health.usnews.com/health-news/diet-fitness/articles/2009/11/02/building-a-diet-that-lowers-inflammation">arachidonic acid</a>, according to U.S. News. Diets lower in this molecule have anti-inflammatory effects and have been shown to <a href="http://www.ncbi.nlm.nih.gov/pubmed/12548439">improve symptoms in rheumatoid arthritis patients</a>. The way you cook your meat could also be a factor, says Daniluk. Grilling it on high can result in <a href="http://www.cnn.com/2010/HEALTH/07/02/how.make.grilling.safe/index.html">inflammatory carcinogens</a>, and a sugary marinade won't do you any favors, either. Keep in mind, the experts say, that some saturated fat is needed. Just be sure to consume in moderation.




  • Alcohol


    Alcohol is naturally irritating to our insides, says Daniluk, but shouldn't cause lasting problems unless you overdo it. With a few too many drinks, however, <a href="http://health.usnews.com/health-news/diet-fitness/articles/2009/11/02/building-a-diet-that-lowers-inflammation">bacteria can more easily pass through the intestinal lining</a>, leading to irritation and inflammation, according to U.S. News. "It's immediate sugar when it's metabolized," says Black, "so you have to weigh the benefits and drawbacks." Small amounts of alcohol have been linked to lower risk of <a href="http://www.huffingtonpost.com/2012/01/30/drinking-benefits_n_1233544.html">heart disease</a> and <a href="http://www.huffingtonpost.com/2011/08/19/alcohol-alzheimers-risk_n_931698.html">Alzheimer's</a>, for example, "but if you get past a certain threshold, you stop getting the positive effect," she says.




  • Omega-6 Fatty Acids


    The average American gets more omega-6 fatty acids via diet than omega-3s, but this <a href="http://www.huffingtonpost.com/2012/11/08/foods-fight-inflammation-diet_n_2079331.html#slide=1721411">imbalance can lead to inflammation</a>, according to U.S. News. "We're thirsty for omega 3s, which can turn off the inflammatory messengers," says Daniluk. To quench that thirst, cut back on omega-6 heavy seeds and vegetable oils and add more fatty fish and walnuts.




  • Milk


    While moderate intake of low-fat dairy can actually <a href="http://online.wsj.com/article/SB10001424052702303612804577531092453590070.html">guard <em>against</em> inflammation</a>, whole milk or even two-percent is still high in saturated fat and could mean trouble. But a <a href="http://usatoday30.usatoday.com/tech/science/2009-08-30-lactose-intolerance_N.htm">majority of adults have at least some difficulty digesting milk</a>, so overdoing it could trigger a <em>true</em> inflammatory reaction, says Black.




  • MSG


    There's some research in animals to suggest that the preservative and flavor enhancer <a href="http://www.ncbi.nlm.nih.gov/pubmed/18178378">monosodium glutamate can create inflammation</a>. While few of MSG's effects are understood in much depth, it may be best to avoid, the experts say. "We probably don't really understand the mechanism behind MSG [causing inflammation]," says Black, "but it's not a chemical your body is used to. It's not like it's a part of broccoli."




  • Gluten


    Even without a diagnosis of celiac disease, a number of people <a href="http://www.slate.com/articles/health_and_science/medical_examiner/2013/02/gluten_free_diet_distinguishing_celiac_disease_wheat_allergy_and_gluten.html">report feeling better after eliminating gluten</a> from their diet. In fact, a full <a href="http://www.huffingtonpost.com/2013/03/06/gluten-free-diet_n_2818954.html">30 percent of American adults are now actively avoiding gluten</a>. Science is still largely inconclusive on what's been called "gluten intolerance," but Daniluk thinks sensitivity that leads to bloating or digestion changes could be an inflammatory response to gluten.




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