June 16, 2021 - 7:31pm
what leavening brings to flour, nutrition-wise
So I was reading "Cooked" by Michael Pollan, which is a wonderful book about the natural history of food preparation. He has a long chapter about bread. He begins with a remarkable thought. He quotes a food chemist at UC Davis saying that you could not survive on wheat flour, but you could on bread. There is no elaboration given to this, but it seems that the reason is something like the microbial action of the yeast (and sourdough in particular) renders the flour more digestable. Does anyone have any biochemical insight about that? References perhaps? I find that kind of remarkable. I mean, in what way can our bodies not completely digest unleavened flour?
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This article has a great review of the topic: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6261201/
In short, fermentation, through various means, helps inhibit some of the factors (tannins, phytates, protease inhibitors) that limit our body's ability to process, absorb, etc. certain proteins and minerals. The paper gives a great example of how fermentation essentially increased the digestibility of plant proteins (normally difficult for humans) almost to the level of meat (much more digestible).
So yes - living off bread is much better than living of raw grains/flour (although I think I'll give both a miss).
Thank you. That's precisely what I'm looking for. That's pretty fascinating. It would seem that gramivores (grass-eating herbaceous animals) don't have this problem. They can easily digest cellulose, which humans cannot. I believe many do this partly by doing fermentation in their gut. For humans, undigested cellulose is still valuable as roughage, but not as a nutrient.
So you'd have to assume that unfermented grain products, like carbonate-leavened biscuits, pie crusts, pasta, and such, aren't doing one a lot of good nutritionally, if made with white flour.
"They can easily digest cellulose, which humans cannot."
Side note, if I may, about human digestion:
There is a certain human gut bacteria (small intestine, but also possible in the stomach, I think), which happens to be endemic in Mexco, and Central and South America, that does digest or process cellulose and turns it into a form of carbs/glucose that humans can absorb.
This is beneficial for a population that engages in a lot of physical activity and might not be able to get enough food. The bacteria improves efficiency of digestion and calorie "absorption."
But... when people with that gut bacteria no longer mainly engage in physical daily work or no longer have meager diets, the excess calories from cellulose make them obese.
In the US, the "potential" calories from that fiber/cellulose are not counted in the Nutrition Info box on packaging. So two people could eat identical servings of granola, or identical apples, and the one with that bacteria would extract more calories.
"So you'd have to assume that unfermented grain products, like carbonate-leavened biscuits, pie crusts, pasta, and such, aren't doing one a lot of good nutritionally, if made with white flour."
And that is one of the big reasons people of developed Western-civilization countries are obese, sick, and have a high incidence of diabetes.
That would explain why diabetes is even more prevalent among some indigenous people groups (the Navajo come to mind locally, among others). If you have any links to more info on this, I would love to read more.
Mary
I'd argue the current high rates of diabetes in American indigenous populations has more to do with historical racist and anti-indigenous policies that extracted these populations from their original carefully cultivated and curated food sources (the former traditional diet of which is actually quite healthy and diverse) and instead forcibly relocated them to hostile and unfamiliar environments with limited food access and limited means of improving that access.
Take for example fry bread (delicious, but terrible for your health)- a now very well known (to non-indigenous Americans) food. The origins of fry bread is revelatory of the above stated forces in action - conceived during the "Long Walk" (forced 300 mile relocation of the Navajo by the U.S. government). The people were given very limited provisions, consisting mostly of flour, salt, and lard, and thus was born fry bread.
The legacy of historical racism continues to insert their influence on these populations today, compounded by multi-generational poverty and limited opportunities for advancement (education, jobs, etc.). Simply put, eating healthy is expensive and impoverished populations (urban, rural, indigenous, immigrant, everyone) don't get much of a choice. Cheap and affordable food typically has more calories (fat or carbs). Plus it keeps you going through the day and provides a mild "good" feeling (sugar and endorphins) even though they are terrible in the long run.
I've long lost those links. The bookmarks might be on a hard drive or two salvaged from dead desktop computers. My problem being not having a desktop computer any more, nor any idea what I may have filed them under, or what filenames to look up to find bookmark files for Netscape-mozilla-firefox.
I seem to recall that the doctors who discovered this were "tropical medicine" specialists. The kind that know what stool and blood tests to run, looking for intestinal parasites after a tourist comes back from south america.
As a nurse, you may know better than I the right search-words to use.
Unfortunately, bariatric specialists may not be good sources to find info on this. Almost all the bariatric patients I've known were kind of "rushed" (that's too harsh a word. what works better?) into surgery without exploring to see if they had some of the more common reasons/"drivers" of over-eating. And of course, the bariatric surgery never fixed the underlying reasons. The doctors and hospitals made their money, and the underlying reasons would still need other doctors and specialists.
"And that is one of the big reasons people of developed Western-civilization countries are obese, sick, and have a high incidence of diabetes."
If these products were just made of cellulose, I'd have to argue with that. If the cellulose isn't digested, it isn't going to make anyone obese. The obesity is from all the other caloric crap they add to these things.
That is fascinating, however, about cellulose digestion-capable gut bacteria in certain populations.
Where I wrote: "And that is one of the big reasons people of developed Western-civilization countries are obese, sick, and have a high incidence of diabetes."
It was specifically in response to the one sentence I quoted from Justkeepswimming. The antecedant to that "that" was: "So you'd have to assume that unfermented grain products, like carbonate-leavened biscuits, pie crusts, pasta, and such, aren't doing one a lot of good nutritionally, if made with white flour." Or at least my intention was such.
Therefore I specifically meant "... biscuits, pie crusts, pasta and such ... made with white flour."
So, then if I understand you, we're in agreement: excess carbs made with white flour are making people obese.
My _other_ point, was that _fiber_ can also make people obese, but _only if_ they _also_ have that particular gut bacteria which I can't find the reference for. In that case, they are unknowingly absorbing more calories than they realize.
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Just for fun, I'll bring up another related point: some people's obesity is cured by _giving them_ bacteria, via a "fecal transplant."
I think we still have an issue here. My understanding was that in most people, white flour was NOT digested. That was the assertion I made in the beginning that was confirmed. In that case, it doesn't provide any nutrient that would make people obese. If white flour carbs are mostly undigestable cellulose, it won't make people obese. My point is that unleavened white flour products that DO make people obese have a lot of added fats that do.
It's not that plant-based flours carbohydrate content is mostly indigestible cellulose - rather there are an assortment of starches in flour, some digestible (and perfectly capable of giving us cavities and going straight to our thighs) and some indigestible (which fermentation and some gut bacteria can partially free up) by humans.
If you look at the (above) label for KAF bread flour, you'll see a division of under "total carbohydrates" - Dietary fiber (of which cellulose is one component, in addition to inulins, lignins, pectins, etc.) makes up only a small portion (<1 g). The remainder of the carbohydrates (total carbs - dietary fiber = ~22 g) are perfectly digestible by the human gut and capable of making us fat.
I am inclined to agree with idaveindy - the bran of wheat definitely has more indigestible carbohydrates, hence why whole wheat flours have higher noted levels of dietary fiber (KAF's whole wheat flour lists 3 g vs the <1 for their white wheat flour).
So you CAN live on white flour, maybe just not very well. Is that what's going on here? I don't think my original question has been answered. Sounds like although a nutrition expert says that you cannot survive on wheat flour, you can sure get fat on it!
I guess it is matter of how you define "living." You can "live" on a pure white flour diet in the sense that you won't starve to death - depending on the quantity you consume, you can have adequate caloric intake that will provide you with enough fuel to go about your day. However you would have to eat the raw flour in higher quantities than in a parallel bread diet as bread has more digestible and usable starches, minerals, vitamins, and proteins due to the fermentation process, as compared to the raw flour. However, given the absence of significant amounts of other neccesary macro- and micro-nutrients (fat, some other protein, vitamins, minerals), you would likely quickly succumb to some form of nutritional deficiency related disorder like pellagra.
"Living" on bread would require less food, but would also likely put someone at risk for nutritional deficiencies regardless, even if they are living on heirloom whole wheat, stone ground, sour dough bread - notably calcium, vitamin C, B12, and D - leading to osteoporosis, scurvy, neuropathy, and osteomalacia respectively. A bread diet would probably ward off a nutritional deficiency for a longer time than a raw flour diet, but the person would also eventually succumb to the inevitable.
Then again - I am basing the likelihood of nutritional deficiencies on the assumption that you are taking about the most basic kind of bread - water, flour, yeast, and salt. But there are so many kinds of bread and bread products - perhaps I could not survive on plain boules, but I could live off a nice panettone with eggs, chocolate, fruit, and citrus in the mix or a curry bun stuffed with meat and vegetables.
I suspect when Pollan is talking about surviving on bread, but not flour, there is certain level of euphemistic whimsy. Bread is such a culturally rich and human concept, it has come to signify more than just existing as a food. Bread has such important roles in community forming, meal time rituals, politics etc. - Perhaps he was referring to the way in which bread not only nourishes the body, but also the spirit, in a way raw flour just does not do.
That seems very clear. Thank you. Now, as far as nourishing the spirit, I suspect there are cultures that would be spiritually nourished with just drop biscuits or porridge.
"If white flour carbs are mostly undigestable cellulose, it won't make people obese."
Hmmm. My understanding is that white flour, the endosperm of wheat, is not cellulose. It is starch, but not cellulose, and is therefore completely broken down into glucose molecules. The bran would be cellulose.
Maybe mwilson or Debra Wink can enlighten us.