Obesity is a well-established risk factor for a whole host of diseases, including diabetes, heart disease, and even cancer. Yet, not everyone who is obese will go on to develop these conditions, and are in fact "metabolically healthy." And now, a new study may explain why: inflammation.
Researchers from University College Cork in Ireland found that lower levels of inflammation are associated with being metabolically healthy, whether you're obese or not.
"From a public health standpoint, we need better methods for identifying which obese people face the greatest risk of diabetes and heart disease," study researcher Catherine Phillips, B.Sc., Ph.D., said in a statement. "Inflammatory markers offer a potential strategy for pinpointing people who could benefit most from medical interventions."
The new research, published in the Journal of Clinical Endocrinology & Metabolism, is based on data from 2,040 people between the ages of 50 and 69 who were part of the Cork and Kerry Diabetes and Heart Disease Study, Phase II., between 2010 and 2011. All the study participants were interviewed on their lifestyle habits, and also underwent testing on their body mass indexes, inflammatory markers and metabolic profiles.
Researchers found an association between inflammatory markers and metabolic health of the study participants, no matter their weight. Being metabolically healthy was indicated by having low levels of white blood cells and acute-phase response proteins (which grow in number during inflammation), as well as higher levels of the anti-inflammatory hormone adiponectin.
Inflammation is a natural body process -- it means your immune system has sensed a threat, and is mobilizing to respond to it -- but too much of it can be bad for health. This blog post from Eating Well summarizes the dangers of chronic inflammation well:
Chronic or systemic inflammation is when the "protect me" signal misfires (which is not a good thing). "Essentially, white blood cells inappropriately move into tissues, causing destruction," explains Floyd Chilton, Ph.D., director of the NIH-sponsored Center for Botanical Lipids and Inflammatory Disease Prevention at Wake Forest Baptist Health School of Medicine in North Carolina. This reaction can happen anywhere in your body. "If [it] happens in the heart, you wind up with heart disease; if it happens in the joint, it's arthritis; in the brain, it might be dementia," Chilton says.
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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.
"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 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.
<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 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.
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.
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."
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.