Food for Gut: Indole-3-carbinol in Vegetables may prevent Colon Cancer

Colon Cancer: Symptoms, Causes and Treatment

The colon, or large intestine, is where the body extracts water and salt from solid wastes. The waste then moves through the rectum and exits the body through the anus. Colon cancer, is the developed at the colon or rectum. A cancer is the abnormal growth of cells that have the ability to invade or spread to other parts of the body. Signs and symptoms may include a change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool, that lasts longer than four weeks, blood in the stool, persistent abdominal discomfort, cramps, change in bowel movement, weight loss and feeling tired all the time.

Most colorectal cancers are due to old age and lifestyle factors, with only a small number of cases due to underlying genetic disorders. Some risk factors include diet, obesity, smoking and lack of physical activity. Dietary factors that increase the risk include red and processed meat as well as alcohol.

Treatments used for colorectal cancer may include some combination of surgery, radiation therapy, chemotherapy and targeted therapy. Cancers that are confined within the wall of the colon may be curable with surgery, while cancer that has spread widely are usually not curable, with management being directed towards improving quality of life and symptoms.


I3C in Colon Cancer Treatment

I3C: Indole-3-carbinol is produced endogenously from naturally occurring glucosinolates contained in a wide variety of plant food substances. Dietary indoles are potent candidates for chemotherapeutic compounds; however, the exact mechanism by which they exert these effects is not completely understood. I3C has been shown to suppress the proliferation of a wide variety of cells, including breast cancer cells, colon cancer cells, prostate cancer cells, and endometrial cancer cells. One potential mediator of the effects of I3C in colorectal cancer is the aryl hydrocarbon receptor (AHR) signaling pathway. The AHR is an orphan cytosolic protein that can only influence transcription after it dimerizes with a ligand and translocates to the nucleus. Once bound, the AHR can link to its binding partner AHR-nuclear translocator and induce transcription of a number of genes by binding to the xenobiotic response element on the genome. Owing to its ability to bind various toxins and xenobiotics, stimulation of AHR is thought to provoke malignant transformation in certain tissues, while imparting a protective role in others.


Vegetables Can Help to Maintain a Healthy Gut and Prevent Colon Cancer

Some observational studies have reported significant associations between high intakes of cruciferous vegetables and lower risk of several types of cancer. Cruciferous vegetables differ from other classes of vegetables in that they are rich sources of sulfur-containing compounds known as glucosinolates. The potential health benefits of consuming cruciferous vegetables are attributed to compounds derived from the enzymatic hydrolysis (breakdown) of glucosinolates. Among these compounds is indole-3-carbinol (I3C), a compound derived from the degradation of an indole glucosinolate commonly known as glucobrassicin.

Recent research shows that mice fed on a diet rich in indole-3-carbinol which is produced when we digest vegetables from the Brassica genus were protected from gut inflammation and colon cancer. This study offers the first concrete evidence of how I3C in the diet can prevent colon inflammation and cancer, by activating a protein called the aryl hydrocarbon receptor (AhR) (Mechanism discussed in the above section). AhR acts as an environmental sensor, passing signals to immune cells and epithelial cells in the gut lining to protect us from inflammatory responses to the trillions of bacteria that live in the gut.

Researchers from Francis Crick Institute 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. However, when they 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 tumours which were also more benign. Also, the researchers found that AhR is vital for repairing damaged epithelial cells. Without AhR, intestinal stem cells fail to differentiate into specialised epithelial cells that absorb nutrients or generate protective mucus. Instead, they divide uncontrollably which can ultimately lead to colon cancer.

We often think of colon cancer as a disease promoted by a Western diet rich in fat and poor in vegetable content, and these results suggest a mechanism behind this observation. Many vegetables produce chemicals that keep AhR stimulated in the gut. They 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.

This study in mice suggests that it’s not just the fiber contained in vegetables like broccoli and cabbage that help reduce the risk of bowel cancer, but also molecules found in these vegetables too. This adds to the evidence that a healthy diet, rich in vegetables, is important. Further studies will help find out whether the molecules in these vegetables have the same effect in people, but in the meantime there are already plenty of good reasons to eat more vegetables.

©BforBiotech by Bedadyuti Mohanty, Assistant Managing Editor by Profession and Bio-technologist by heart.

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