A cautionary tale of mucus fore and aft
Let’s engage in a sort of thought experiment. Let’s assume that way back in the early days of medicine doctors always wanted to see us cough up mucus from our lungs. Since mucus is a kind of breeding ground for all kinds of nasty bacteria, it would make sense in the olden, pre-antibiotic days to want patients to hack up as much of this stuff as possible to get it out of the body where the bacteria could no longer wreak their havoc.
Let’s assume that doctors of old–who didn’t realize that the excess mucus was the body’s way of ridding itself of something foreign, i.e., the bacteria or viruses causing the infection–started equating coughing up ‘healthy’ amounts of mucus with good health. It’s not too far a leap to imagine these doctors supposing that if they could get their patients to cough up stuff all the time, the respiratory system would stay clear of the mucus that harbors all the pathogens that cause lung problems. Druggists might come up with concoctions that would cause people to cough, even if they didn’t need to.
Now let’s imagine that the idea that coughing up large amounts of mucus-laden sputum reaches the point of a national obsession. People, especially the elderly for whom respiratory infections are much more dangerous, discuss with one another how much sputum they produce and how often. If they don’t cough as much or as productively as they perceive those around them are doing, they go to their doctors who prescribe a sputum inducing medicine for them. People everywhere are obsessed with keeping their respiratory systems clean.
Now, someone comes along and says, Hey, world, I’ve got the perfect product to keep everyone coughing productively. Use my product and before you know it you’ll be coughing your head off and ridding your lungs of all kinds of nasty junk. Here, try one of these. It’s called a cigarette.
In today’s modern world we all know what cigarettes do. The irritation of the smoke damages the lining of the tubes that carry air into and out of the lungs. As the damage continues, goblet cells (so called because they resemble little goblets), the cells that produce mucus, increase in size and number, producing more mucus to coat and protect the cells lining the airways. As the smoking continues, so does the damage, and so does the double duty of the goblet cells. Ultimately, in far too many people, the production of the protective mucus from the goblet cells isn’t able to keep up with the damaging effects of the smoke and cell injury occurs. As these cells are damaged, they cease to function properly, and ultimately die. They are then replaced by new cells, which themselves go through the same cycle. Somewhere along the way one of these cells, due to the damaging effects from the smoke, undergoes a malignant transformation and starts to reproduce itself. When this happens lung cancer is born.
We know what happens to the lungs with smoking. We know that all the coughing and mucus production isn’t a good thing–it isn’t protecting us from disease; it is the result of disease. But if we lived in a society that worshipped bringing up mucus every day, how long would it take us to figure out that smoking wasn’t particularly good for us?
Into this society of mucus lovers a researcher comes along and writes a paper showing how cigarettes cause an increase in mucus. He talks to the press and tells them about his research, saying, ‘I’ve now figured out how these wonderful cigarettes work to improve our mucus production. They damage the cells, which then make and release more mucus to protect themselves. It’s really wonderful how the body responds thusly. Now that we know how it all works, let’s go out and smoke even more.’
Preposterous, you’re probably thinking. Only if you live in a society that doesn’t worship regular mucus production.
We live in a society that worships regular bowel movements. Doctors for the last few hundred years have focused much of their effort in ensuring the regularity of their patients. Many people, the elderly especially, are obsessed with moving their bowels daily. Most people, if asked, would probably reckon that it’s not good to have fecal matter just sitting around in the colon. Get it out of there, they would say. It can’t be healthy. Just as it escaped the notice of our doctors in the scenario I imagined above that animals in the wild don’t bring up copious amounts of mucus daily, it has escaped the notice of doctors today that animals in the wild, especially carnivorous animals, don’t always have daily bowel movements, and that when they do, such BMs aren’t always huge and loose.
Into our bowel-regularity-worshipping society there has come a substance that ensures regularity. It’s called fiber. It is sold everywhere in diverse forms. All manner of ‘experts’ from our doctors to our grandparents encourage us to consume plenty of fiber. If we can’t get enough from the foods we eat to achieve regularity, we are encouraged to buy supplements. Everyone is on the regularity bandwagon and, by extension, the fiber bandwagon. The much despised Jane Brody has written countless times on the virtues of fiber, WebMD encourages us to get our share, even C. Everett Coop exhorts us to keep the fiber coming. And, despite numerous studies showing that fiber doesn’t really do squat for us healthwise, everyone continues to recommend it.
To paraphrase John Huston: Evidence? We ain’t got no evidence. We don’t need no evidence. We don’t have to show you any stinking evidence.
Into this society of bowel movement lovers a researcher comes along and writes a paper showing how fiber causes an increase in regularity. Our intrepid researcher’s name is Dr. Paul L. McNeil; he is a cell biologist at the Medical College of Georgia. I’ll let him tell how it all works.
When you eat high-fiber foods, they bang up against the cells lining the gastrointestinal tract, rupturing their outer covering. What we are saying is this banging and tearing increases the level of lubricating mucus. It’s a good thing.
Indeed?
He goes on:
It’s a bit of a paradox, but what we are saying is an injury at the cell level can promote health of the GI tract as a whole.
Really?
He goes on to explain that even though epithelial cells usually live less than a week, they are regularly bombarded, in most of us at least three times a day, as food passes by.
These cells are a biological boundary that separates the inside world, if you will, from this nasty outside world. On the cellular scale, roughage, such as grains and fibers that can’t be completely digested, are a mechanical challenge for these cells.
But in what he and colleague Dr. Katsuya Miyake view as an adaptive response, most of these cells rapidly repair damage and, in the process, excrete even more mucus, which provides a bit of cell protection as it eases food down the GI tract.
As reported in ScienceDaily
In research published in 2003 in Proceedings of the National Academy of Sciences, Dr. McNeil showed proof of his then decade-old hypothesis that cells with internal membranes use those membranes to repair potentially lethal outer-membrane injuries. A recent paper published in Nature in collaboration with Dr. Kevin Campbell’s laboratory at the University of Iowa showed how human disease, including certain forms of muscular dystrophy, can result from a failure of this mechanism.
An outer membrane tear is like an open door through which calcium just outside the cell rushes in. Too much calcium is lethal but that first taste signals the vulnerable cell it better do something quick. With epithelial cells, several of the internal mucus-filled compartments fuse together within about three seconds, forming a patch to fix the tear. In the process the compartments expel their contents so, almost like a bonus, extra mucus becomes available to lubricate the GI tract.
And a final telling paragraph.
The scientists aren’t certain how many times cells can take a hit, but they suspect turnover is so high because of the constant injury. Potentially caustic substances, such as alcohol and aspirin, can produce so much damage that natural recovery mechanisms can’t keep up. But they doubt a roughage overdose is possible.
(You can click here to read this study in its entirety in PLoS Biology)
So, we have a situation where a product causes damage to the cells lining a tube, causing them to produce a lot of mucus in an attempt to protect themselves. In the process many of these cells die and are replaced by new cells. And this is perceived as a good thing.
My question is: is it really a good thing?
Below are the results of my search in Pub Med using the search terms “defecation frequency and
cancer”. While other factors are at least hypothesized as related to colon cancer, defecation frequency is stated in every case to be unrelated to frequency of colon cancer. In fact at least 1 study concludes that “Although the most common bowel habit was once daily this was a
minority practice in both sexes; a regular 24 hour cycle was apparent in only 40% of men and
33% of women”. The Studies are listed below for the curious. As always thanks for the time and
space (in this case a lot of it).
Hi Mark–
I’m going to insert my comments here. Skip on down for the actual papers.
So, there isn’t a correlation between colon ca and frequency of defecation. Interesting. And the average person (at least in the groups studied) defecated less often than once per day. No s**t? I couldn’t resist. Anyway, that’s interesting as well.
Thanks for your diligence on this. It’s an interesting fact to know given the focus on daily bowel movements as a protective mechanism against colon cancer.
Best–
MRE
Prospective study of bowel movement, laxative use, and risk of colorectal cancer among women.
* Dukas L,
* Willett WC,
* Colditz GA,
* Fuchs CS,
* Rosner B,
* Giovannucci EL.
Department of Nutrition, Harvard School of Public Health, Boston, MA, USA.
The authors prospectively examined the association between bowel movement frequency,
laxative use, and the risk of colorectal cancer in 84,577 women of the Nurses’ Health Study
living in the United States, 36-61 years of age and free of cancer in 1982. Between 1984 and
1996, 611 incident cases of colorectal cancer were documented. After controlling for age, body
mass index, fiber intake, postmenopausal status and hormone use, physical activity, and use of
laxatives, the relative risks associated with having bowel movements every third day or less,
compared with those with bowel movements once daily, were 0.94 (95% confidence interval
(CI): 0.69, 1.28) for colorectal cancer, 0.88 (95% CI: 0.62, 1.26) for colon cancer, and 1.18 (95%
CI: 0.63, 2.20) for rectal cancer. Compared with women who never used laxatives, the
multivariate relative risks associated with weekly to daily laxative use were 1.00 (95% CI: 0.72,
1.40) for colorectal cancer, 1.09 (95% CI: 0.76, 1.57) for colon cancer, and 0.68 (95% CI: 0.29,
1.57) for rectal cancer. These findings do not support an association between infrequent bowel
movement, laxative use, and risk of colorectal cancer and indicate that simple questions directed
at bowel movement frequency are unlikely to enhance our ability to predict colorectal cancer
risk.
Association of bowel movement frequency and use of laxatives with the occurrence of
symptomatic gallstone disease in a prospective study of women.
* Dukas L,
* Leitzmann MF,
* Willett WC,
* Colditz GA,
* Giovannucci EL.
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA.
OBJECTIVES: The authors prospectively examined the association between bowel movement
frequency (used as a proxy for intestinal transit), laxative use, and the risk of symptomatic
gallstone disease. METHODS: A total of 79,829 women, aged 36-61 yr, without a history of
symptomatic gallstone disease and free of cancer, responded to a mailed questionnaire in 1982
that assessed bowel movement frequency and use of laxatives. Between 1984 and 1996, 4,443
incident cases of symptomatic gallstone disease were documented. Relative risks (RRs) of
symptomatic gallstone disease and 95% confidence intervals (CIs) were calculated using logistic
regression. RESULTS: After controlling for age and established risk factors, the multivariate
RRs were, compared to women with daily bowel movements, 0.97 (95% CI 0.86-1.08) for
women with bowel movements every third day or less, and 1.00 (95% CI 0.91-11.1) for women
with bowel movement more than once daily. No trend was evident. As compared to women who
never used laxatives in 1982, a significant modest inverse association was seen for monthly
laxative use, with a multivariate RR of 0.84 (95% CI 0.72-0.98), and weekly to daily laxative use
was associated with a RR of 0.88 (95% CI 0.78-1.02). CONCLUSIONS: These findings do not
support an association between infrequent bowel movements and risk of symptomatic gallstone
disease in women, and indicate that simple questions directed at bowel movement frequency are
unlikely to enhance our ability to predict risk of symptomatic gallstone disease. The slightly
inverse association between use of laxatives and risk of symptomatic gallstone disease may be
due to a mechanism that is not related to bowel movement frequency.
PMID: 11280540 [PubMed - indexed for MEDLINE]
Bowel movement, use of laxatives and risk of colorectal adenomatous polyps among women
(United States).
* Dukas L,
* Platz EA,
* Colditz GA,
* Willet WC,
* Giovannucci EL.
Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA.
BACKGROUND: Infrequent bowel movements and use of laxatives have been hypothesized to
increase risk of colorectal neoplasia. However, the few existing epidemiologic studies in humans
have been inconclusive. PURPOSE: To investigate prospectively the associations of bowel
movement frequency and laxative use with the occurrence of adenomatous colorectal polyps in
women. METHODS: A total of 17,400 women 36-61 years of age, without previous diagnosis of
cancer or polyps, responded to a mailed questionnaire in 1982 that assessed bowel movement
frequency and use of laxatives and had an endoscopy between 1984 and 1996. Between 1984 and
1996, 906 cases of adenomatous polyps (496 classified as small ( or = 1 cm) and 52 unclassified) were documented. Relative risks (RRs) of adenomas and 95%
confidence intervals (CIs) were calculated using logistic regression. RESULTS: After controlling
for adenoma risk factors, the multivariate RRs associated with having bowel movements every
third day or less compared to once daily were 0.9 (95% CI: 0.7-1.2) for total colorectal
adenomas, 1.0 (95% CI: 0.7-1.5) for large adenomas and 1.0 (95% CI: 0.7-1.3) for adenomas of
the colon only. The multivariate RRs associated with weekly to daily laxative use compared to
never use were 0.9 (95% CI: 0.7-1.1) for total colorectal adenomatous polyps, 1.0 (95% CI:
0.7-1.5) for large adenomas and 0.8 (95% CI: 0.6-1.2) for colon adenomatous polyps only.
CONCLUSION: These findings do not support an association between infrequent bowel
movement or laxative use and risk of colorectal adenomas.
Cancer. 1984 Oct 1;54(7):1475-7. Links
Colorectal cancer and bowel habits.
* Nakamura GJ,
* Schneiderman LJ,
* Klauber MR.
In a retrospective case-control study comparing 100 colorectal cancer patients with 100 age-,
race-, and sex-matched hospital controls and 51 spouse controls, no significant differences were
observed in the historical frequency of bowel movements, presence of constipation, or use of
laxatives between cases and controls. There is a suggestion of greater suppository or enema use
in both control groups as compared to patients with colorectal cancer.
PMID: 6467171 [PubMed - indexed for MEDLINE]
S Afr Med J. 1981 Oct 10;60(15):571-3. Links
Cancer of the colon and rectum in the coloured population of Johannesburg. Relationship to
diet and bowel habits.
* Maisto OE,
* Bremner CG.
In the Coloured population of Johannesburg, the incidence of carcinoma of the colon and
rectum estimated over an 11-year period (1970-1980) is 1,33 and 1,08/100 000 respectively per
year. This is lower than the incidence reported in Whites and appears to be even lower than that
reported in South African and Zimbabwean Blacks. A survey of dietary factors in this population
showed a diet which was high in protein, low in fats and high in bulk. The frequency of bowel
action was higher than in both Whites and Blacks. These factors support Burkitt’s hypothesis
which states that races with a high-bulk diet have a lower incidence of large-bowel cancer.
PMID: 7280914 [PubMed - indexed for MEDLINE]
Am J Clin Nutr. 1978 Oct;31(10 Suppl):S239-S242. Links
Diet, transit time, stool weight, and colon cancer in two Scandinavian populations.
* MacLennan R,
* Jensen OM,
* Mosbech J,
* Vuori H.
In samples of adult men from two Scandinavian populations with 4-fold differences in colon
cancer incidence, a comparison was made of estimated food records over 4 days, defecation
habits, mouth-to-anus transit time, and stool weight. The “high incidence” group consumed more
white wheat breads and total meat and beer, but less potatoes and milk than the “low incidence”
group. Defecation habits were similar. Transit time and stool weight had few significant
correlations with diet and defecation habits, but stool weights were higher in the low incidence
group. The results are consistent with a possible protective role of dietary fiber, unrelated to
transit time.
PMID: 707381 [PubMed - indexed for MEDLINE]
Lancet. 1977 Jul 30;2(8031):207-11. Links
Dietary fibre, transit-time, faecal bacteria, steroids, and colon cancer in two Scandinavian
populations. Report from the International Agency for Research on Cancer Intestinal
Microecology Group.
* Maclennan R,
* Jensen OM.
A comparison of dietary intake and faecal characteristics in population samples from two areas
of Denmark and Finland with 4-fold variation in colon-cancer incidence suggests that the
aetiology of colon cancer may be multifactorial and is not associated in a simple manner with
dietary fat, neutral steroids, acid steroids, or their bacterial metabolites. However, meat
consumption was greater in the high-incidence areas. Higher intakes of dietary fibre and milk in
the low-incidence area suggest a possible protective effect, unrelated to mouth-anus transit-time.
Further careful dietary and metabolic studies are needed to clarify the relationships between
possible carcinogenic and protective effects of diet.
PMID: 69826 [PubMed - indexed for MEDLINE]
: Lancet. 1977 Jul 16;2(8029):110-1. Links
Bowel transit-time and stool weight in populations with different colon-cancer risks.
* Glober GA,
* Kamiyama S,
* Nomura A,
* Shimada A,
* Abba BC.
It has been suggested that the risk of cancer, polyposis, and diverticulosis of the large bowel
increases with bowel transit-time. Hence, Japanese inhabitants of Hawaii, in whom the risk of
these diseases is high, would be expected to have longer transit-times than Japanese in Japan, in
whom such risks are low. However, bowel transit-times were similar in Japanese groups. Stools
from the Hawaii Japanese did weight significantly less than the specimens from Japan, and this
factor may be indirectly related to the risk of colorectal cancer, polyposis, or diverticulosis in the
Japanese.
1: Gut. 1992 Jun;33(6):818-24. Links
Defecation frequency and timing, and stool form in the general population: a prospective
study.
* Heaton KW,
* Radvan J,
* Cripps H,
* Mountford RA,
* Braddon FE,
* Hughes AO.
University Department of Medicine, Bristol Royal Infirmary.
Because the range of bowel habits and stool types in the community is unknown we
questioned 838 men and 1059 women, comprising 72.2% of a random stratified sample of the
East Bristol population. Most of them kept records of three consecutive defecations, including
stool form on a validated six point scale ranging from hard, round lumps to mushy.
Questionnaire responses agreed moderately well with recorded data. Although the most common
bowel habit was once daily this was a minority practice in both sexes; a regular 24 hour cycle
was apparent in only 40% of men and 33% of women. Another 7% of men and 4% of women
seemed to have a regular twice or thrice daily bowel habit. Thus most people had irregular
bowels. A third of women defecated less often than daily and 1% once a week or less. Stools at
the constipated end of the scale were passed more often by women than men. In women of child
bearing age bowel habit and the spectrum of stool types were shifted towards constipation and
irregularity compared with older women and three cases of severe slow transit constipation were
discovered in young women. Otherwise age had little effect on bowel habit or stool type. Normal
stool types, defined as those least likely to evoke symptoms, accounted for only 56% of all stools
in women and 61% in men. Most defecations occurred in the early morning and earlier in men
than in women. We conclude that conventionally normal bowel function is enjoyed by less than
half the population and that, in this aspect of human physiology, younger women are especially
disadvantaged.
PMID: 1624166 [PubMed - indexed for MEDLINE]
Hi, Dr. Mike.
A little off the track here, but do you believe in supplementing with acidophilus to boost the healthy flora in the intestine? Also, what’s your opinion on the “yogurt exception” which states that the carbs in yogurt are actually lower than the nutrition label suggests due to the healthy bacteria consuming the lactose?
Hi Diana–
I don’t supplement myself nor do I have my patients supplement for a couple of reasons. First, I’m not really a bowel-oriented kind of guy, especially where a low-carb diet is concerned. Second, if one eats the right kind of diet, the bacteria in the bowel will respond and grow in the proper proportions. There are a zillion different kinds of bacteria in the GI tract, all in constant warfare and turf battles. If the food coming down the gut has a lot of carbs in it, then those bacteria that flourish on carbs will have a field day and reproduce in much greater numbers than those will that subsist on fat. If fat comes down the tract instead of carbs, the opposite happens. As long as the diet is a proper one (read: whole food, low-carb), then I figure the gut flora will take care of themselves. Second, I’ve never seen (and I’m not saying I’ve seen everything in print; I’m not particularly interested in this topic, so I haven’t spent a lot of time searching) a decent study showing that acidophilus does anything positive for those on low-carb diets.
As to the yogurt question: I don’t know. I don’t really eat yogurt unless forced, so I haven’t paid much attention to anything having to do with it.
Best–
MRE
>Below are the results of my search in Pub Med using the search terms “defecation frequency and
cancer”. While other factors are at least hypothesized as related to colon cancer, defecation frequency is stated in every case to be unrelated to frequency of colon cancer. In fact at least 1 study concludes that “Although the most common bowel habit was once daily this was a minority practice in both sexes; a regular 24 hour cycle was apparent in only 40% of men and
33% of women”. The Studies are listed below for the curious. As always thanks for the time and
space (in this case a lot of it).<
It’s so weird talking about bathroom habits…
I like to have at least one BM a day just because I *feel* better. Cancer risk or not, I just don’t like going less. I’ve gone less most of my life and hated it the whole time.
I guess it’s a case of different strokes for different folks. Or maybe different poops for different groups. Whatever sets well with your spirit is probably the best thing.
Best–
MRE
My son has Duchenne Muscular Dystrophy. Are you saying that he should not be having high-fibre foods as his mucous-repair mechanism does not work? So his epithelial cells are not getting repaired?
Hi Jen–
I’m not saying anything about a mucus-repair mechanism. The study I wrote about simply showed that the way fiber works in the GI tract is by damaging the cells, which then secrete mucus to protect themselves. There mucus producing systems work fine; it’s the chronic damage from the fiber that is problematic.
Hope this helps–
MRE
The issue with yogurt is that carbohydrate content on labels is calculated indirectly (total kilocalories minus kilocalories for protein and fat), so the kilocalories of the lactic acid contained within are counted as carbohydrate, massively overstating the carbohydrate count.
There is very little lactose left once yogurt has fermented; indeed, many lactose-intolerant individuals can tolerate yogurt.
If you haven’t liked yogurt in the past, but like dairy products generally, you might try Stonyfield’s organic fullfat “cream on the top” yogurt. IMO, it’s as decadently wonderful as cream cheese or sour cream or marscapone. It is somewhat tart, and I tend to mix in some strawberries or blackberries or even a sugar-free coffee syrup or such to cut the tartness a bit. But it’s wonderfully creamy, yummy stuff.
Yogurt was *always* a good and yummy food when I was growing up. There was only one brand and hardly anyone ate it. Then it became popular or trendy and they started making it lowfat and nonfat and adding all these thickeners and such to it to make up for the cream they removed and started replacing fruit-flavorings with chemical flavorings and all that. *That* crap is not yogurt anymore than any other factory-produced food.
Dear Doctor Eades–
I am reminded of the time a doctor once asked me about how often I went, and at what time…as if TIME had any bearing on my health!
My response to him was that I don’t keep a “potty diary” and I go when I need to. I let the raw vegetation from salads, and the grains from baked goods and sandwiches do their work for me–no measuring, no worries about “getting enough” fiber, and my only bout of constipation came after a cheese-tasting festival.
Just GOING is good enough for me. Time, quantity, size, texture, and all that mean nothing–it’s all just fermented compost anyway.
There has been a suggestion planted in the TV viewer’s mind (from a PBS fundraiser) that the average human needs 35 grams of fiber daily for good health. We’d have to consume an entire tree, a bale of hay, or a bushel of grain to achieve that amount! Of course, the lecture giver DID finish up by pimping various OTC fiber supplements. She should’ve pushed Mexican food instead of pills–the beans, raw onion, raw lettuce, and raw tomato would’ve done the same thing!
Hi Wenchypoo–
Both fiber and frequent bowel movements are highly overrated.
Cheers–
MRE
Mike, I’m confused. Am I correct in understanding that you believe the fiber in fruits and vegetables is harmful and to be avoided? Should we be eating a meat and fat only diet since fiber damages the GI tract?
I’ve seen your blog linked to elsewhere on the internet in support of such a diet and was curious if that was really what you support?
No, I don’t think the relatively small amount of fiber that comes in as part of a good, whole-food low-carb diet causes problems. But I do think taking large amounts of fiber supplements, wheat bran, etc. is probably not a great idea.
Cheers–
MRE