
Scientists studying how fiber influences the microbiome - HillaryBriss
https://www.nytimes.com/2018/01/01/science/food-fiber-microbiome-inflammation.html
======
jfv
Maybe someone with a knowledge of nutrition and medicine can clear this up for
me.

As I understand it, there are two types of fiber that are lumped into the term
"dietary fiber": soluble fiber and insoluble fiber. I believe that both are
fermented in the large intestine but soluble fiber is the one that primarily
supports flora through fermentation, while insoluble fiber is used for more of
a physical effect, to draw water into the stuff that's going through.
Apparently soluble fiber also helps to increase the viscosity of the stuff
going through the stomach, which slows digestion (considered to be a good
thing).

One of the studies mentioned in the article uses inulin (soluble fiber -- the
kind you'd find in a supplement like Benefiber). With regards to regulating
sugar, metabolism, and gut flora I imagine that soluble fiber is the one we
should be focusing on. Yet it seems rare to distinguish the two.

I know that both fibers are often found in the same food (typically fruits and
vegetables) but some processes (like juicing) remove insoluble fiber while
leaving the soluble fiber intact. So it's commonly believed that juice
"doesn't have fiber", which is untrue.

Isn't it time we start distinguishing between the two when we talk about the
health effects? Am I just completely wrong in how I understand this?

~~~
twic
AIUI, insoluble fiber didn't get fermented. Insoluble fiber basically means
cellulose; to digest cellulose, you need some pretty serious engineering, like
four stomachs [1], or a huge caecum [2], or, er, a two-pass process [3].
Humans don't traditionally have any of those, so we don't digest cellulose to
a significant degree. There are other components of food classified as
insoluble fiber, but the only significant one is lignin, at on the order of
10-20% of the mass of cellulose [4], and that's so hard to digest you
basically have to be a fungus to do it [5]. Apparently even termites don't
break it down much.

Soluble fibres are oligosaccharides with weird bonds that we can't break down,
but that bacteria can. They're nothing like insoluble fibre, except that they
come from plants. They're polymers, but this is biology, every other thing is
a polymer. They're not really even fibrous. We absolutely should distinguish
them.

This review is pretty accessible, and covers a lot of ground:

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614039/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614039/)

I would write more, but i'm going to cook some lentils instead!

[1]
[https://en.wikipedia.org/wiki/Ruminant](https://en.wikipedia.org/wiki/Ruminant)

[2]
[https://en.wikipedia.org/wiki/Equine_nutrition#The_cecum_and...](https://en.wikipedia.org/wiki/Equine_nutrition#The_cecum_and_large_intestine)

[3]
[https://en.wikipedia.org/wiki/Cecotrope](https://en.wikipedia.org/wiki/Cecotrope)

[4]
[http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2621.1981....](http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2621.1981.tb04521.x/full)

[5]
[https://en.wikipedia.org/wiki/Lignin#Biodegradation](https://en.wikipedia.org/wiki/Lignin#Biodegradation)

~~~
epmaybe
I think the main reason we can't break down cellulose is because we don't have
the enzymes to do so. It's not as if cellulose is actually all that different
to polysaccharides we _are_ able to digest, it simply has beta 1->4 glycosidic
bonds [1] between the glucose molecules instead of alpha 1->6 glycosidic bonds
that are digestable by humans.

edit: upon some more skimming of the review article, even with the enzymes we
may not have the conditions in which cellulose could be degraded, hence the
"four stomachs" and other methods.

[1]:
[https://en.wikipedia.org/wiki/Cellulose](https://en.wikipedia.org/wiki/Cellulose)

------
bL79
As someone who has recently been battling IBS after coming back from a trip
it's become pretty clear to me that gut bacteria/micro fauna/whatever plays a
significant role in our health that Western medicine is only just beginning to
understand. I'd wager in another few decades we will see a whole bunch of new
treatments based around an improved understanding of the gut.

It's unfortunate because I (anecdotally) see Doctors dismiss gut micro-fauna
balance as quackery, especially since alternative medicine often points to it
as a source of trouble (e.g. Candida overgrowth). Sadly it's common to see
conventional doctors attack straw-men when discussing alternative medicine's
view on the gut rather than acknowledging what we do/don't know. Not saying
'alternative' medicine is right but it's clear to me a healthy gut is critical
to a healthy person. I crave more scientifically backed data - I've really
begun to appreciate how impacted quality of life becomes when you're dealing
with chronic digestive issues.

Adding fiber and probiotics to my diet has helped me tremendously. Shocker -
eating green, healthy looking things instead of fast food poison makes me feel
better too. After a fair bit of research this probiotic seemed like the best
value with a solid strain list. Probably best to refrigerate as soon as
possible though.

[https://www.amazon.com/gp/product/B00JEKYNZA/ref=oh_aui_deta...](https://www.amazon.com/gp/product/B00JEKYNZA/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1)

Also found this article helpful.
[https://www.ncbi.nlm.nih.gov/pubmed/22504002](https://www.ncbi.nlm.nih.gov/pubmed/22504002)

~~~
Fomite
The problem is that so much of what alternative medicine points to _is_
quackery, even if they get the system potentially correct.

I've worked a bit in gut microbiome stuff, and a bunch of the things alt
medicine advances about it still fall in the "That's not how any of this
works..." realm.

~~~
bL79
Oh, absolutely. It's just that I'd rather read more interesting insight on
what we do know rather than a tangential attack on how Autism and gut yeast
can't be related. I guess it's similar to a lot of more controversial topics
where the dialogue is often narrated by extreme viewpoints rather than the
more reasonable middle ground

------
adrianmonk
Definitely tangential to the main point, but I don't really think it's
accurate what one of the biologists implies about McDonald's food:

> _“It’s basically what you’d get at McDonald’s,” said Dr. Bäckhed said. “A
> lot of lard, a lot of sugar, and twenty percent protein.”_

As far as I can tell, McDonald's stopped frying their french fries in lard
back in 1990 and other products before then. (See
[http://articles.chicagotribune.com/1990-07-24/business/90030...](http://articles.chicagotribune.com/1990-07-24/business/9003020215_1_terri-
capatosto-fast-food-firm-fast-food-industry) .)

Fast food has plenty of nutrition problems, but it doesn't seem helpful to
make up ones that don't actually exist.

Maybe he just used the wrong word since he's from Sweden, though.

~~~
bagacrap
Given that the rest of the sentence refers to sugar and protein, he probably
means fat. Non-native speaker and/or mildly inaccurate translation. Lard isn't
really worse for you than other fats anyway, so I'm not sure why he'd focus on
that.

