One of the current “hot topics� in health research is how a certain kind of inflammation might affect our risk of heart disease, stroke, diabetes and even cancer. Normally, inflammation is a good sign – when your thumb swells up after you accidentally bang it with a hammer, it tells you that your immune system is sending white blood cells and other, hormone-like substances to help start the healing process. But not every kind of inflammation is that easy to see, and it’s the invisible kind that takes place throughout our cells and tissues, over and over again, that is attracting so much attention. COX-2 is an enzyme in our bodies that boosts the production of inflammatory substances. Normally, these proteins and hormone-like substances are churned out by our immune systems with no ill effects. Under certain conditions, however, they might actually help cancer cells multiply and spread. That’s why one type of anti-inflammatory drugs, collectively called COX-2 inhibitors, are under study for a potential role in preventing or treating cancers of the colon, uterus, breast, prostate and other tissues. And now, scientists are investigating whether the way we eat could also influence the kind of chronic inflammation that might be linked to cancer risk and other health problems. Around the world, different researchers are focusing on different aspects of the issue. Some are looking at how two families of polyunsaturated fats may work together to play a protective role. Omega-3 fats are found mainly in fatty fish such as salmon, mackerel, and albacore (white) tuna, but are also found in flaxseeds and flaxseed oil, walnuts and canola oil. Omega-6 fats are found in many common vegetable oils (corn, safflower, sunflower). All are considered heart-healthy because they don’t raise blood cholesterol. But when omega-6 fats predominate over omega-3 fats, something else happens: our bodies seem to increase COX-2 levels and produce more of the hormone-like substances that promote inflammation. When omega-3 and omega-6 fats are more balanced in the diet, fewer of these inflammatory substances are produced. This is why some scientists believe that if we boost omega-3 fats with regular consumption of naturally fatty fish or sources like flax, and reduce our excess use of vegetable oils, spreads and high-fat snacks made with them, we might make the COX-2 in our bodies less active, and decrease the amount of inflammatory hormones that might be associated with cancer risk.

Other scientists are seeking to determine if inflammation may be one reason that obesity has been linked to higher cancer risk. Research now suggests that the body’s fat cells produce cytokines (proteins that promote low-grade inflammation) and that the distribution of body fat might also play a role. A study in the Journal of the American Medical Association shows that one measure of inflammation increased by more than 50 percent in obese women whose fat was mainly in their hips and thighs (“pear-shaped�), and by more than 400 percent in obese women with significant waistline fat (“apple-shaped�).

Interestingly, some studies now show that regular exercise may have precisely the opposite effect on the immune system, and may reduce levels of inflammatory proteins. This might help to explain why research has linked regular physical activity with lower cancer risk. Still other scientists, including many sponsored by the American Institute for Cancer Research, are investigating how an overall plant-based diet might help keep inflammation in check. Antioxidant nutrients and phytochemicals in fruits and vegetables protect cells’ DNA from damage that can lead to cancer; and some evidence now suggests they may also lower production of inflammation-promoting hormones. In fact, a wide variety of natural phytochemicals found in fruits and vegetables are under investigation for possible COX-2 lowering effects. All of this evidence linking diet to the kind of chronic inflammation associated with cancer risk is still preliminary, however, and it would be premature to change our diets if this was the only reason to do so. Of course, it isn’t the only reason – a plant-based diet with plenty of fruits and vegetables, maintenance of a healthy weight and regular exercise is already a strategy that is estimated to lower cancer risk by 30 to 40 percent. We know that it works – the incoming research about inflammation may soon help us get a better idea of some of the how and why.