I was reading this study and saw something unusual, well, unusual for me. Here’s the study:

Faecal pH Value And Its Modification By Dietary Means In South African Black And White Schoolchildren, South African Medical Journal, May 1979

From our studies it would seem reasonable to conclude the following: faeces from groups of rural and urban prepubertal Black schoolchildren are significantly more acid than those of White children of the same age.

The finding of the study isn’t surprising. I’ve spoken about it for years … how a high-fiber diet feeds bacteria in the colon, causing them to produce organic acids, like short-chain fatty acids. Those acids lower the pH (make more acidic) of feces. A more acidic environment in the colon is protective against colon cancer. I talked about this in my posts on resistant starch (RS). RS isn’t exactly fiber, but it feeds colonic bacteria quite well. There’s a lot of resistant starch in cooked, cooled cornmeal, a staple food in Africa. (Here’s my post on making ugali, the bread of Africa.) (Cooked, cooled pasta and potatoes also have a lot of resistant starch.)

I came across this photo while researching baobobs in Madagascar. I really liked it.

Here’s the thing that surprised me:

Feces Collection: Black Schoolchildren
Each pupil was given a cardboard plate, 23 cm (9 inches) in diameter, and a square of paper towel for covering the sample. Pupils went to the toilets in batches to lessen confusion over sampling and to avoid ‘cheating’. Approximately 90% of pupils are able to pass a stool on request, which is a common phenomenon among Black children.
…
Previous studies have indicated that Black children, compared with White children, defaecate roughly twice as frequently, and have about half the transit time.

Defecation on demand. Not in America!

Here’s what they were eating:

Among rural Blacks, maize meal in one form or another is still the staple diet, supplemented in certain parts with kaffir corn (Sorghum vulgare), millet and wheat products. Additional foods include dried peas, cowpeas, groundnuts, pumpkin, kaffir melon and other vegetables, fruit and wild greens (m’lino, morogo). Meat is consumed irregularly and milk is usually consumed in small quantities. … Most children eat plenty of fruit, according to region and season, such as oranges, pineapples, guavas, bananas, papaws and mangoes. Most of these are good sources of crude fibre.

I think it’s their diet, in part at least, that allows them to defecate on demand. And that diet is very McDougall-like: starch-based, low-fat. They were getting less than 15% of their calories from fat – quite low. Maize or corn meal is usually eaten 3 times a day, along with every meal, like bread. That’s a lot of resistant starch.

For the white schoolchildren (who didn’t defecate on demand, but were sent home with a carton):

Their diet is substantially the same as that eaten by Whites in Western countries. It is high in energy value, protein (especially animal protein), and fat (especially animal fat), and low in carbohydrate foods (most of which are refined).

Here in the West, passing stool is often problematic. That’s what I’ve learned in speaking to patients and people over the years. And it seems more problematic for women. This study bears that out:

Defecation Frequency And Timing, And Stool Form In The General Population: A Prospective Study, Gut, June 1992.

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.

I’ll throw up a couple graphs from that study. Here’s frequency. Black is men, hatched is women. That peak at 24 means that many people visited the bathroom once every 24 hours. A blip at 12 means that they emptied their bowels every 12 hours, or twice a day. Men were more prone to that:

Here’s time of day. Women tended about an hour later than men:

You know what else bears that out? That defecation is a problem in the West? The array of products at the drug store meant to assist stool passage: MiraLax, Metamucil, FiberCon, Ex-Lax, Citrucel, etc.

By the way, I saw this study on an older video by Dr. Greger: