Stool Size and Breast Cancer Risk

Women eating plant-based diets may have lower breast cancer rates because they have larger bowel movements. In The Best Detox, I described the role of the liver in removing toxins from the blood stream, which can then be jettisoned through the bile into the digestive tract, and eliminated. Our gut is our body’s disposal system; anything it wants to get rid of, it throws down the trash chute. One can imagine our enterocytes, the cells lining our intestinal wall, as a vast array of trash pickers, resource recovery workers. They’re sifting through the river of garbage flowing past and picking up anything of use–a vitamin here, a mineral there, such that by the end there isn’t much left that’s desirable—and what’s left truly gets, ahem, dumped.

The digestive tract is also how we get rid of excess hormones and cholesterol. Our body expects there to be an ever-flowing torrent of intestinal contents to flush this stuff out to sea. We did, after all, evolve over millions of years on a diet centered on unrefined plant foods. We aren’t designed for burgers and milkshakes; we are designed for fiber, and lots of it.  Anthropologists estimate we evolved eating 100 grams of fiber a day or more!

So our body is counting on a massive, quick-flowing stream of contents through our digestive tract, and when there’s excess estrogen in the trash, our body expects it to just zip right out. But what if we don’t consume an adequate amount of fiber to soften and bulk up that intestinal flow? What if that river dries up into just a slow trickle of sludge? We still have the same number of trash pickers, but the volume and speed of the flow is way down, so they’re finding all sorts of stuff that otherwise would have been lost. Uh oh—that means they’re picking back up the estrogen that your body intentionally dumped, and thrusting it right back into the system. Fiber to the rescue, diluting, speeing, and bulking up the flow, so lots of stuff never even makes it to banks of the river to be picked at and inappropriately saved. This may be why women who eat lots of plants (the only place fiber is found) have lower estrogen levels and a lower risk of breast cancer, as detailed in today’s video pick above.

As I show in my video Food Mass Transit, meat-eating women average a four-day mouth-to-anus transit time, likely too long to meet the target 200 gram (half pound) minimum fecal output for cancer prevention. People don’t realize you can have daily bowel movements and still be effectively constipated. You can be regular, but four days late. In other words, what you’re flushing today you may have eaten last week. If you want to test it for yourself, all you need to do is eat a big bowl of beets and see when things turn pretty in pink. Ideally, to reach that half-pound target, your intestinal transit time should be down in the 24 to 36 hour range.

Small bowel movements are also associated with a variety of other diseases such as appendicitis, colon cancer, constipation, and diverticulitis. See my 2-min. video Stool size matters. Just eating antioxidant-rich foods can improve stool weight. See Bulking Up on Antioxidants (2-min). And finally, check out Bowels of the Earth to find out which country has the largest (and smallest) average stool size. Find out who’s #1 at number 2!

In health,
Michael Greger, M.D.

Image credit: Taylor McConnell / Flickr

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William C
William C1 years ago

Thank you.

Past Member 3 years ago

The writer understand better the mind of people what they want to learn through their writing therefore this article is outstanding. Thanks!!!Breast Implants Hub

Duane B.
.5 years ago

Thank you for sharing.

Dale Overall

Being a carnivore I will always eat meat and am tired of being accused of being cruel just because someone with a vegan or veggie lifestyle decrees that it is. If eating meat was unnatural then we would die of toxicity every time we digested the stuff. There are veggies that we must cook such as potatoes, (broccoli is best cooked as it interferes with thyroid function if raw but that does not stop me from eating raw broccoli when the mood hits me especially with dip).
Until we evolve where we can eat rocks and other inorganic matter on the planet we all feed on the demise of something be it plant or otherwise. If one thinks that it is cruel to add honey to your tea because you believe that we are stealing from the bees--fine, do not add honey to your tea. Stop lecturing to the rest of us who eat eggs, meat, dairy, poultry and whatever.

I just put a slice of lemon in water and sacrificed all those seeds which will never grow into new lemon trees. Perish the thought and yesterday I murdered asparagus and ate that, tonight the Swiss Chard was dumped into boiling water for a short steaming session along with defenceless carrots and broccoli! Heaven help the quinoa that I will consume tomorrow!
I try and eat a balanced diet and do not aways eat meat, fish, poultry each day but that is what I choose and I horrors, even limit the meat to the size of a deck of cards per serving. Sorry BBQ meat guys, that is a scarey thought too!

J.L. A.
JL A6 years ago


Cecily Pretty
Cecily P6 years ago


Carol P.
Carol P6 years ago

What a load.

Dr. Gergen actually believes that we evolved on a plant-based diet? Hah! Our early ancestors ate primarily meat. Most of the plant-based foods that are part of our current diet weren't even edible a few thousand years ago!

And I'm not sure why he thinks that a person would need to eat a vegan diet to get the benefits of eating a high fiber diet. Meat eaters can eat fruits and vegetables too.

This is just another case of an animal advocate using the worst-case scenarios to try to make his personal dietary choices appear better by comparison. Neither extreme is healthy.

care2 - please get this joker's propaganda off of your website!

Megan Beery
Megan Beery6 years ago

I never knew that, thanks!

Jessica R.
Jessica Reff6 years ago


Lynne Brittany
Lynne B6 years ago

Thanks for the info, something to think about.