We have always been told to eat more vegetables as they are rich in many nutrients and vitamins as well as the ability to protect us from many diseases. Researchers from the Francis Crick Institute showed that eating green vegetables like cabbage and broccoli could help prevent colon cancer.
The study published in immunity showed that eating vegetables rich in indole-3-carbinol (I3C) can protect mice from colon cancer by activating a protein receptor called the aryl hydrocarbon receptor (AhR).
AhR is an environmental sensor that is important for immunological responses and inhibiting inflammation in our gut; researchers have found that AhR is also essential in intestinal homeostasis as it’s deficiency leading to the inability of intestinal stem cells to repair and differentiate in response to tissue damage which can lead to the development of colorectal cancer.
In this study, researchers have studied genetically modified mice that lack AhR gene and wild-type mice that have the AhR gene and compared the results.
"We studied genetically modified mice that cannot produce or activate AhR in their guts, and found that they readily developed gut inflammation which progressed to colon cancer," explains first author Dr. Amina Metidji from the Francis Crick Institute. "However, when we fed them a diet enriched with I3C, they did not develop inflammation or cancer. Interestingly, when mice whose cancer was already developing were switched to the I3C-enriched diet, they ended up with significantly fewer tumors which were also more benign."
While on studying normal mice that have the AhR protein, they found that they developed tumors when fed purified control diet that has fewer AhR-promoting chemicals, while the mice fed chow diet or a diet enriched with I3C did not develop any.
"Normal mice on the purified control diet developed colon tumors within ten weeks, whereas mice on the standard chow didn't develop any," explains co-corresponding author Dr. Chris Schiering, who worked on the study at the Crick and now works at Imperial College London. "This suggests that even without genetic risk factors, a diet devoid of vegetable matter can lead to colon cancer."
"Seeing the profound effect of diet on gut inflammation and colon cancer was very striking," says senior author Dr. Gitta Stockinger, Group Leader at the Francis Crick Institute. "We often think of colon cancer as a disease promoted by a Western diet rich in fat and poor in vegetable content, and our results suggest a mechanism behind this observation. Many vegetables produce chemicals that keep AhR stimulated in the gut. We found that AhR-promoting chemicals in the diet can correct defects caused by insufficient AhR stimulation. This can restore epithelial cell differentiation, offering resistance to intestinal infections and preventing colon cancer.
He also mentioned that although the genetic factors that increase the risk of colon cancer cannot be altered, it can be alleviated by eating an appropriate diet full of vegetables.
"A number of epidemiological studies suggested that vegetables may be protective against cancer," explains Gitta. "However, there is very little literature on which vegetables are the most beneficial or why. Now that we've demonstrated the mechanistic basis for this in mice, we're going to investigate these effects in human cells and people. In the meantime, there's certainly no harm in eating more vegetables!"
Watch the video below to learn more about AhR and how it is activated by eating vegetables to protect our gut.