Break an ankle and it may start to look like a tree trunk. Unsightly, yes, but this external swelling (inflammation) is a vital part of healing. But what happens when inflammation is internal, ongoing, and undetected? Low-level inflammation is one of the greatest health threats facing Americans, warn experts, and you may not even know you have it.

Chronic inflammation occurs when the immune system becomes hyperactive in response to irritants—from smoking, stress, or a poor diet—and no longer switches off its efforts to heal the body. These factors stimulate the release of chemicals that activate the immune system’s inflammatory response in an effort to undo the stresses placed on the body, says Samer Koutoubi, MD, PhD, professor in the Department of Nutrition and Exercise Science at Bastyr University.

Find out if you have inflammation by taking the CRP test.

C-reactive protein (CRP) accompanies inflammation, making it a great gauge for measuring inflammation levels in the body (see “Take the CRP Test,” page TK). “When CRP remains high and low-grade inflammation becomes constant and untreated, it weakens the body’s immune system and paves the way for many chronic diseases, particularly heart disease,” Koutoubi says. In fact, an eight-year study involving nearly 28,000 women published in the New England Journal of Medicine found that more than half of the women who eventually developed heart disease had high CRP levels, even when their LDL (“bad”) cholesterol levels were in a healthy range.

Smart diet and lifestyle changes can reduce and may even prevent heart-damaging inflammation, says Koutoubi. The first thing to consider is losing any excess weight you may be carrying around. Studies have shown that people with excess weight around the middle often have elevated CRP levels. Next, follow these four simple inflammation-taming guidelines.

Decrease omega-6s, increase omega-3s.

Omega-6 fatty acids found in cheap, ubiquitous vegetable oils such as corn, soy, safflower, and sunflower oils are the precursors for compounds that turn on the inflammatory response. Omega-3 fatty acids, such as those in cold-water fish, turn it down, says Barry Sears, MD, author of Toxic Fat: When Good Fat Turns Bad (Nelson, 2008). “Most Americans consume way too much omega-6 compared to omega-3 fats,” Sears says.

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Limit processed, packaged, and fast foods, which are often high in omega-6s. Instead focus on foods rich in inflammatory-neutral monounsaturated fats such as olive oil and nuts, and anti-inflammatory long-chain omega-3s found in sardines, rainbow trout, and mackerel. Sears encourages a daily purified omega-3 fish oil supplement (1,000 mg); vegans can incorporate two tablespoons of omega-3 rich chia, flax or hemp seeds, and algae-derived omega-3 supplements to help squelch inflammation.

Reduce red meat

A 2009 study found that among 880 middle-aged adults, those who ate the most red meat had higher markers of inflammation. One reason may be that the arachidonic acid found in red meat stimulates the inflammation process, says Jessica Butcher, RD, a registered dietitian in Grand Haven, Michigan.

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Butcher recommends eating tofu, tempeh, lentils, beans, and fish more often. “When you do eat red meat, choose game meats and grass-fed organic beef since these tend to have less arachidonic acid and more inflammation-busting omega-3 fats,” says Butcher. The industry norm of feeding livestock corn and soy increases arachidonic acid levels in meat, explains Sears.

Avoid foods cooked at high temperatures.

Acrylamide is a potentially carcinogenic compound formed when starchy foods are cooked for extended periods of time at temperatures greater than 250 degrees. This includes potato chips, French fries, muffins, donuts, and processed cereals (even otherwise healthy Os and flakes). Scientists from Poland reported recently that people who ate 160 grams (a little under 6 ounces) of acrylamide-rich potato chips daily for a month saw their CRP levels nearly double and their oxidized LDL cholesterol rise.

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Cut back on all fried and baked goods. Acrylamide is not created by boiling, and few uncooked foods contain worrisome amounts. “In general, foods closest to their natural state such as fruits, vegetables, and whole grains will generate the least amount of inflammation,” says Butcher. Anti-inflammatory curcumin, an antioxidant in turmeric (found in many curry mixes), may reduce the damaging effects of acrylamide. Brighten up soups, stews, stir-fries, and brown rice with a teaspoon of this spice.

Get a handle on stress

According to the American Psychological Association, a third of all Americans are living with extreme stress—with money and work being leading culprits. When stress becomes persistent, it can contribute to disease-provoking inflammation by turning on the pro-inflammatory machinery in the body. In fact, in 2008 the European Heart Journal reported that people with significant work stress were 68 percent more likely to suffer heart disease than those who had less anxiety. Moreover, people who say they are alone or have little social support are more likely to suffer chronic inflammation and heart disease, say scientists.

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Scientists have shown that laughter induced by 30 minutes of humorous TV can significantly reduce markers of inflammation. A good chuckle breaks patterns of negativity and helps you let go, says stress expert Debbie Mandel, author of Addicted to Stress (Jossey-Bass, 2008). Mandel also recommends relaxation rituals including aromatherapy, drinking a cup of herbal tea, or listening to music, plus changing up your daily routine, engaging supportive friends, and exercising regularly as effective ways to handle what life sends your way. To break out of your hermit ways, Mandel encourages seeking out healthy and meaningful social activities that involve like-minded people. “Cooking classes, exercise clubs, and community gardening are great ways to make new friends and promote a healthy, inflammation-fighting lifestyle,” she says.