Researchers are increasingly recognizing that chronic inflammation is an underlying cause of many health problems, including diabetes, cancer, dementia and heart disease. It is thought to be to blame for more than half of deaths worldwide.
This exacerbated immune system response is one consequence of growing older. “As we age, our ability to control inflammatory responses goes down, leaving us with gradual, accumulative inflammation,” says Simin Nikbin Meydani, lead scientist on the Nutritional Immunology Team at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. This process has even been given a name: inflammaging.
But aging is just part of the picture. Though you can’t erase the years, lifestyle factors play a big role in helping to control inflammaging — and that means there is much that you can do to counteract and slow it down. Eating plenty of foods that suppress low-grade inflammation — and cutting back on the foods that promote it — is one of the most effective steps you can take.
Not all inflammation is harmful. Acute inflammation is the way that the body initiates healing. “It’s a strong defense mechanism that’s triggered when the immune system activates to fight off a bacterial or viral infection,” says Frank Hu, chair of the Department of Nutrition at the Harvard T.H. Chan School of Public Health. The damaged or infected area of the body releases proteins called cytokines and other compounds that make blood vessels more permeable. This draws white blood cells called leukocytes to the area and allows them to enter the tissues so that they can destroy the threat. Without this response, infections would linger and wounds would fester.
Though acute inflammation subsides pretty quickly, chronic inflammation sticks around long past the point of helpfulness.
“If acute inflammation is like a fire, chronic inflammation is more like smoldering smoke,” Hu says.
How it can harm you
Diseases that may seem to have little in common — such as Type 2 diabetes, arthritis, heart disease, cancer, Alzheimer’s and even covid-19 — are all caused, or worsened, by high levels of chronic inflammation. “When inflammation is consistently elevated, it contributes to cellular damage, causing injury to a variety of tissues and organs,” says Chris D’Adamo, director of research at the Center for Integrative Medicine at the University of Maryland School of Medicine.
This process plays a role in cancer cells developing and multiplying out of control, in the creation of the beta amyloid plaques that lead to Alzheimer’s, and in the buildup of plaque in the arteries that causes heart disease. “And any disease that ends in ‘–itis’ — such as arthritis, colitis, diverticulitis — is a disease of inflammation,” D’Adamo says.
Inflammation also contributes to the development — and severity — of respiratory diseases such as asthma, bronchitis and covid-19, the ailment caused by the coronavirus.
“The cytokine storm [where inflammatory compounds destroy healthy tissues] that results in more severe covid symptoms and increases risk of death is one result of out-of-control inflammation,” Meydani says. A recent study, published in Nature Medicine, measured levels of four inflammatory cytokines in more than 1,400 patients hospitalized with covid-19. People with the highest levels were most likely to suffer severe symptoms or die of the disease.
The food effect
“Several lifestyle factors — including sleep, stress and physical activity — strongly influence inflammation levels,” says Penny Kris-Etherton, a professor of nutritional sciences at Pennsylvania State University. But emerging research indicates that diet can have the most profound effect — positive or negative.
Many of the foods that are prevalent in a typical American diet are the ones that fuel unhealthy levels of inflammation. “Red meat, processed meat, saturated and trans fats, added sugars, fried foods, and refined carbohydrates all directly trigger pro-inflammatory responses,” Hu says.
In a recent study published in the Journal of the American College of Cardiology, Hu and other researchers at Harvard T.H. Chan School of Public Health followed more than 200,000 men and women for up to 32 years. “We found that the people who ate a diet containing the most pro-inflammatory foods had a 46 percent increased risk of heart disease,” Hu says.
The study design also helped the researchers identify foods that had the greatest anti-inflammatory potential. “Certain foods stood out, including green leafy vegetables, dark yellow vegetables, fatty fish, extra-virgin olive oil, whole fruits [especially berries, pears and apples], whole grains, coffee and tea,” Hu says. Levels of C-reactive protein (a sign of systemic inflammation) were significantly lower in the group that ate more of these foods. “Reducing blood levels of inflammatory markers helps reduce future risk of disease,” Hu says.
Another recent study found that eating 1 to 2 ounces of walnuts a day reduced inflammation markers in the blood. In part, that may be because walnuts are high in omega-3 fatty acids. “Most people have way too much omega-6 in their diets relative to omega-3,” D’Adamo says. “We need both, but too much omega-6 contributes to chronic inflammation.” You’ll end up with unhealthy levels of omega-6 if you consume too much grain-fed meat and fried or processed foods, and not enough omega-3 rich ones, such as fish, walnuts and flaxseed.
Creating the right diet
Adding foods that reduce inflammation to your diet is a great start, but experts caution against focusing on just a few specific ones. “If you aim for an overall healthy dietary pattern that’s mostly plant-based, you will get anti-inflammatory benefits,” Kris-Etherton says. Numerous studies have shown that following a Mediterranean-style diet — plenty of vegetables, fruits, nuts, whole grains and olive oil, along with some fish — can lower inflammatory markers and reduce the risk of inflammation-related conditions, such as heart disease and cancer.
Anti-inflammatory foods work their magic because they contain compounds that inhibit the release of cytokines. Colorful fruits and vegetables contain antioxidants, such as beta carotene, vitamin C and vitamin E, as well as unique plant compounds called flavonoids (also found in tea and coffee). Whole grains are rich in folate and minerals such as selenium. And extra-virgin olive oil — as well as some spices, such as ginger and turmeric — boasts compounds that inhibit the inflammatory cyclooxygenase-2 enzyme, the same one that is blocked when you pop some ibuprofen.
“Eat a wide variety of healthy foods, especially fruits and vegetables, and you’ll get all the components that have anti-inflammatory properties,” Meydani says. “We know that when you have high levels of these anti-inflammatory foods in your diet, you can significantly reduce levels of inflammation in the blood and tissues throughout your body.”
Just as important, cut back on pro-inflammatory foods. There’s often a synergistic effect between a poor diet and other lifestyle factors that affect inflammation, creating a vicious cycle.
For example, “a poor diet can lead to being overweight, and being overweight might make you less active,” Kris-Etherton says. “Those things can lead you to have more stress and poor sleep.” So controlling those factors, too, will help you tilt the balance and help you tamp down inflammation.
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