The rate of colon and rectal cancer increases among people under the age of 50 the latest striking trend this has alarmed and alarmed doctors who are racing to figure out why. Now a new study has been published gut provides what may be a key insight: specific lipids, or fatty acids, in which they are abundant ultra-processed foods can promote inflammation that causes colon cells to become cancerous.
Colorectal cancer tumor samples from 81 people in the US had too much of the inflammation-promoting lipids, called omega-6 fatty acids, and lacked the helpful lipids, called omega-3 fatty acids, which help stop inflammation.
Inflammation is a normal defense response that is activated by the immune system to heal wounds or fight infection. But when researchers in the 1800s looked under a microscope, colon tumors had “poorly healed wounds,” says Timothy Yeatman, a study co-author and professor of surgery at the University of South Florida. Prolonged inflammation damages cells and interferes with their ability to fight the growth of potentially cancerous cells. Omega-6 fatty acids often come from our diet, Yeatman suspects ultra-processed food it is likely the main source of them.
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“We don’t know the full effect of these ultra-processed foods on our bodies, but we do know that this is one important thing that has changed since the 1950s,” says Yeatman. “Today’s youth, especially rural and poor people, are exposed to these processed foods more than anyone else, because they are cheap and in every fast food restaurant.”
Many ultra-processed foods and fast foods are prepared with seed oil, a common, inexpensive vegetable oil that is chemically processed from seeds such as canola, corn, grapeseed, and sunflower. These oils contain high amounts of omega-6 fatty acids. However, the study was unable to link the lipids detected in colon cancer tumors to a specific food or oil.
“I think the study confirms that diet is important, but it’s probably one of many factors,” says Andrew Chan, a gastroenterologist at Massachusetts General Hospital and professor of medicine at Harvard Medical School, who was not involved in the new study. Chan and other researchers point to genetics, exercise, lifestyle, and chemical or environmental exposures it may also affect the risk of colon cancer. Also, “there is a lot of complexity in the food we eat, how it’s converted, how it’s metabolized, and how it can eventually cause tissue changes around lipids,” says Chan. “So there are still some pieces that need to be filled in to be able to tell a cohesive story about it.”
American scientific He spoke with Yeatman and Chan more about the findings and the possible role of ultra-processed foods in inflammation and colon cancer.
(Below is an edited transcript of the interviews.)
What has past research shown us about the relationship between diet and colon cancer?
CHAN: There has been research in the past looking at the link between colorectal cancer risk and specific dietary patterns that we know are associated with inflammation. Some of these dietary patterns are enriched with specific types of oils, such as those containing omega-6 fatty acids, which are known to be pro-inflammatory. In contrast, there is data showing that dietary patterns enriched with healthy oils, such as the Mediterranean or so-called prudent dietary patterns, are associated with a lower risk. And besides that, they have been specificstudies They have studied the effect of omega-3 fatty acids, such as fish oils, and their ability to have a preventive effect on the risk of colorectal cancer. That was it mostly shown in animal modelsbut there have been some clinical trials suggesting that supplementing one’s diet with fish oil, for example, may be beneficial. Those types of studies they are still consistentso I think more work needs to be done in this area.
Our group and others have also been interested in the idea that some of these lipids responsible for the inflammation that can lead to cancer can also be inhibited by drugs such as aspirin. Aspirin is an anti-inflammatory drug that specifically affects lipids, such as prostaglandins, which can promote cancer. These are helpful steps in the development of new cancer prevention strategies aimed at altering the balance of these lipids and the balance of inflammatory mediators that may be related to some of these lipid pathways.
How do lipids cause inflammation?
YEATMAN: When you get a cut on your hand or your skin, at first it’s swollen and red because of the inflammation, and then it gets better, and that’s because of the inflammation of the solution. Solving lipidsor proresolving lipids, recently discovered by Charles Serhan of Harvard University. And he described something called a “lipid class switch,” which means that the body, as it undergoes normal healing, will go from an inflammatory phase to a resolution phase. Basically he found that there are some of these lipids—mainly omega-3 lipid derivatives—that resolve inflammation. But inflammation, if left unchecked, can lead to cancer.
How does this inflammation affect the development of cancer?
CHAN: Inflammation causes changes in tissues, which can lead to the development of cancer. The tissue may grow in an uncontrolled way where it is difficult for the cells to become normal, so this abnormal cell turnover and excessive cell division can lead to the formation of tumors. We know that inflammation can also create an environment that makes tissue more prone to develop changes in DNA, such as mutations that can lead to cancer. There may also be some effects of inflammation that impair the body’s ability to naturally fight the development of cancer.
I believe that these different lipids and oils may have specific effects and pathways related to inflammation and the ability of tissues to repair themselves in a normal way. This can lead to an environment where some of these tissues can become cancerous due to uncontrolled cell growth.
Why can this imbalance of proinflammatory and proresolving lipids occur?
YEATMAN: The source of these lipids is ultimately the diet. So the excess of proinflammatory lipids in the tumor microenvironment is the smoking gun in relation to the lipids we are consuming. From the 1950s to the present, levels of omega-6 lipids in human body fat, which is the pro-inflammatory side. And that’s probably because of Western dietary changes. And you come back to what those changes are, well, they’re ultra-processed foods. Now, ultra-processing involves more than lipids, but lipids are present in many seed oils, such as soybean oil, canola oil, cottonseed oil, sunflower oil, safflower oil, which are processed and used in foods. Seed oils are cheap, but the bottom line is that they’re in almost everything we eat that comes packaged. For example, if you go to the store and pick up a loaf of bread that hasn’t been baked by a local bakery, you’ll find a whole list of hard-to-identify ingredients in that bread…one of which is generally soybean oil. It’s got everything: bread, chips, hummus, salad dressing, cookies, cakes, pies.
It’s not just seed oil. If you have corn-fed beef, the omega-6-to-omega-3 ratio (may be much higher than that of a grass-fed cow)… so that simple change from corn to grass-fed makes a huge difference in the ratio. But it can be very difficult to find grass-fed beef in the food story. And the reason is that it costs money; I think it takes three years to market a grass-fed chub and maybe a year for corn-fed. So it is much less time for cheaper approach.
Are omega-6 fatty acids bad for health?
YEATMAN: Omega-6 is an essential fatty acid. You should have it, but you don’t need it 30 times to 1 (compared to omega-3). So it’s like everything else: it should be in moderation. But the problem is that we have grossly overused the amount of seed oil in our foods. And I don’t think seed oils are necessarily good for you because we get omega-6s from all kinds of other sources.
Not everyone with exposure to the seed oil will likely have a problem. But I think there is a connection there. Proving these links is difficult because we would have to have a diet history over the years. More research is needed, and someone needs to prove that seed oils, taken in the excessive amounts we are given, are actually safe. And that hasn’t been proven to me yet, so I think the default should be reduced until we know.
