IBD vs IBS: Colon Cancer Risk Explained

Picture an elevator in Park City, Utah, during the Sundance Film Festival. A young woman in white jeans watches the floor numbers tick down with excruciating slowness, already past the point of holding on. She loses control of her bowels before the doors open. That woman is NBC correspondent Chloe Melas, and she tells the story not for shock value but because it is, in her words, the thing nobody says out loud. Never trust a fart, her daughter now tells her, and the line gets a laugh, but behind it sits a decade of blood, urgency, and a body nobody had properly diagnosed (53:00).

Melas was 25 when she first noticed bright red blood on the toilet paper and assumed, like most people would, that it was a hemorrhoid (06:00). It was not. The inflammation that started as proctitis, a localized irritation of the rectum, spread across her colon because she was not consistent with her medication, and she was eventually diagnosed with ulcerative colitis, one of the two major forms of inflammatory bowel disease, or IBD (03:36). The other is Crohn's disease, which can inflame any part of the digestive tract from mouth to anus. For over ten years, Melas did not have what she calls a normal bowel movement (00:00).

Two Different Problems, One Confused Public

The confusion Melas ran into constantly, including from people close to her, is the assumption that IBD and IBS are the same thing. They are not. IBD is a disease: the immune system attacks the digestive tract directly, causing visible, physical damage that shows up on a colonoscopy. IBS, irritable bowel syndrome, is classified as a syndrome, a collection of symptoms like bloating, cramping, and diarrhea that is thought to stem from miscommunication between the gut and the brain along the vagus nerve (04:30). The distinction matters beyond semantics. As Melas puts it, IBS

does not increase your risk of colon cancer like IBD does

That delay falls disproportionately on women. Dr. Lyon cites a multi-center study of 190 newly diagnosed IBD patients: the average time from a woman's first doctor visit to an actual diagnosis was over a year, compared with four and a half months for men with Crohn's disease, and six months versus three months for ulcerative colitis (21:05). The symptoms do not present differently between sexes. What differs is how seriously they get taken; a woman describing stomach pain is often told it is anxiety. A 2025 qualitative study of women with IBS or IBD that Dr. Lyon references found that embarrassment itself becomes a barrier, discouraging women from seeking care in the first place and straining relationships and daily life along the way (19:00).

The stakes behind that delay are rising. Colon cancer, Melas says, is now the number one cancer killer of men and women under 50 in the United States, and both IBD and IBS rates are climbing (08:36). The recommended age for an initial screening colonoscopy has been lowered to 45, but Melas is blunt that the real barrier is cultural squeamishness, not medical risk.

If someone can look in our vagina, they should be able to look at our colon.

What a Normal Bowel Movement Actually Requires

One gap nobody mentioned to Melas for fifteen years, across multiple doctors, was fiber. Women need roughly 30 grams of fiber a day, men roughly 40, yet the average American gets only 16 to 17 grams (23:58, 28:46). Melas assumed she was fine because she ate salads. Then she learned that an entire apple, skin, core, and all, contains only about 4 grams of fiber (24:21). Closing that gap with food alone is harder than it sounds, which is why she turned to psyllium husk, an insoluble fiber that does not dissolve in water but instead turns gel-like, acting, as she describes it, like a scrubber that gathers debris and bulks up stool as it moves through the intestines (32:10). She calls it, somewhat jokingly, nature's natural GLP-1, since adequate fiber also supports cholesterol levels, satiety, and weight management (32:33). Not every fiber works the same way for every gut; Melas found that inulin and chicory root left her doubled over with gas, while psyllium husk gave her what she calls, without irony, beautiful bowel movements (29:20).

Melas also believes her twenties set the stage for her diagnosis, not through any single cause but through an accumulation of urgent care visits and repeated rounds of antibiotics, including Cipro and Flagyl, prescribed for minor infections (33:52). It was after one round of Cipro that she first noticed blood in her stool. Her theory, which she is careful to call personal belief rather than settled science, is that repeated antibiotic use wiped out her gut flora, the bacterial population that keeps the digestive tract functioning, without anything in her diet or lifestyle to rebuild it (34:24). Protein played a role too. Enterocytes, the cells lining the gut, rely on an essential amino acid called threonine to produce mucin, the protective mucus layer inside the intestines, which is part of why a low protein diet can leave the gut unable to repair itself (46:07).

Celiac disease adds another layer of complication, because it is often mistaken for simple gluten sensitivity. Melas spoke with Dr. Benjamin Lebwohl, a Columbia University gastroenterologist and past president of the Society for the Study of Celiac Disease, who explained that celiac disease is a genetic autoimmune condition: the body treats gluten as a foreign invader, and if a parent or child has it, there is a 10 percent chance of developing it too (42:20). The practical catch is that testing requires eating gluten beforehand. Anyone already avoiding gluten before a blood test risks a false negative, since the antibodies the test looks for will not be present (40:53). Self-diagnosing a gluten-free lifestyle, however common it has become, can mean missing the actual diagnosis.

Perhaps the most striking fact in the whole conversation is historical. Beginning in the 1930s, ulcerative colitis was classified as a psychosomatic disease, meaning doctors believed a patient's psychological profile caused the physical illness, rather than treating it as a disease process in its own right (63:14). That framework shaped decades of dismissive care, and traces of it linger every time a woman's stomach pain gets waved off as stress. Melas and her co-author, Judy Battalion, call their book a bowel movement movement, and the phrase works as more than wordplay. The goal is not just better fiber habits or earlier colonoscopies, though both matter. It is permission to say, plainly, that the stool in the toilet is a daily health report, and that reading it honestly, rather than flushing past it in embarrassment, is sometimes the difference between a hemorrhoid and a disease that has already been building for years.