The promises made for the virtues of a tidy bowel are head-turning. Who wouldn't want a flatter stomach, more energy, a clearer complexion, pain-free joints and a better night's sleep?
The idea of cleansing or detoxifying the colon dates back to the ancient Greeks and Egyptians and has fallen in and out of favour through the centuries.
Today, it has growing support in the holistic and integrative medical fields.
One theory for its necessity says that the intestines can't fully eliminate all waste from the body.
The concern is that this material could rot in the colon, producing toxins that invade the body and cause all kinds of unpleasant symptoms, apparently including death.
Oral supplements, herbal teas, laxatives, enemas and colonic irrigation all are touted as ways to clean out the mess.
Dr Ron Shemesh, a Florida-based doctor who is board certified in obstetrics and gynaecology as well as holistic medicine, believes colon therapy has benefits.
"Absolutely," he says. "Addressing nutrient intake and removal of waste in the body will improve overall health."
There's more to it than just popping a pill before resuming your position on the couch.
He tells patients that to enjoy health benefits, they must also adopt a diet of whole foods that is free of alcohol, caffeine and processed and fried foods plus manage stress with such practices as yoga or meditation.
And they must move - that's his code word for exercise.
"People always freak out when I say exercise. But the gut is not going to work unless you move, engage in some form of physical activity," he says.
He also recommends supplements, vitamins and probiotics, certain foods and products that promote the growth of good bacteria in the gut that help with digestion.
All of which, you might think, would leave you with pretty tidy insides, without extra cleansing.
Mainstream medicine mostly restricts the use of laxatives and enemas to people who are severely constipated, or those who need a medical test such as a colonoscopy that requires a clear view of the colon's lining.
Why? Because if you rely on outside agents to move your bowels, they stop doing the job the way nature intended, and your constipation can become chronic. Herbal laxatives can be just as powerful and habit-forming as their chemical cousins.
"In general, I think the idea of colon cleansing is akin to people selling snake oil," says Dr Raymond Cross, a gastroenterologist and director of the Division of the Inflammatory Bowel Disease Programme at the University of Maryland School of Medicine, in the state of Baltimore.
"I don't think it should be done at all," he said.
Dr Cross says it is highly doubtful that the average person is walking around with kilos of old waste in his colon.
"It's not based on any scientific study that I am aware of," he says.
Laxatives, enemas and colon-irrigation procedures have long been used for weight loss.
"I get questions about it a lot," says Dr Denise Edwards, director of the University of South Florida Healthy Weight Clinic.
She says laxative abuse is common in people with eating disorders.
"It sounds appealing: 'I want to start new, flush all this out of my body and start over clean.' But the body is pretty good at removing things on its own," she said.
"And, unless there is a medical problem, laxatives and enemas are not needed and can cause harm."
In addition to causing chronic constipation, risks include dehydration, heart or kidney damage, colon perforation and infection.
Plus, the weight loss achieved through colon "detoxification" is water weight, not fat, and any kilos lost return once you eat or drink again.
One point on which everyone seems to agree: The best way to keep the bowel moving is with a high-fibre diet rich in fruits, vegetables and whole grains and by drinking plenty of water.
Dr Nagi Kumar, a researcher and registered dietitian at the Moffitt Cancer Centre in Tampa, says eating yoghurt with active cultures will increase good bacteria in the digestive tract, which can help with digestion and the absorption of nutrients from food.
What about expensive probiotic supplements, or probiotic-fortified foods?
There is some evidence they can help some people, particularly those with medical conditions that have an effect on their digestion.
Ask your health provider if you need them.
But in general, "the colon or any part of the intestine does not need to be cleansed," Kumar said.
"If enough soluble and insoluble fibre is consumed on a regular basis, the contents of the colon will empty naturally."
KEEPING YOUR COLON HEALTHY
A high-fibre diet may be all you need for colon health. Women should try to eat at least 21g to 25g of fibre a day, while men should aim for 30g to 38g. Here are a dozen high-fibre choices:
FRUITS
• Raspberries: 1 cup, 8g fibre
• Pear: 1 medium, 5.5g
• Apple: 1 medium, 4.4g
GRAINS
• Whole-wheat pasta: 1 cup cooked, 6.2 g
• Barley, pearled: 1 cup cooked, 6g
• Bran flakes: 3/4 cup, 5.3g
LEGUMES (all cooked)
• Split peas: 1 cup, 16.3g
• Lentils: 1 cup, 15.6g
• Black beans: 1 cup, 15g
VEGETABLES (all cooked)
• Artichoke: 1 medium, 10.3g
• Peas: 1 cup, 8.8g
• Broccoli: 1 cup, 5.1g