The recommendations on that page don't make much sense? The foods recommended are not major dietary sources of tryptophan (cf. [1]) and while a variety of fermented foods are mentioned, I am not aware of the use of the crucial bacterium Clostridium sporogenes in any deliberate fermentative cultures, such as are used for yogurt or kombucha, which rather contain [checks fridge] Lactobacillus, Bifidis, and Streptococcus species. But Clostridia are typically found in the gut of breast-fed newborns within a week of birth [2], suggesting they don't need much help.

I will also note that there has been some work done on the incorporation of Clostridium sporogenes into probiotics, but it doesn't come from kefir or miso, and... well... just read it! [3]

1: https://en.wikipedia.org/wiki/Tryptophan#Dietary_sources

2: https://jasbsci.biomedcentral.com/articles/10.1186/s40104-01...

3: https://scholarworks.calstate.edu/downloads/x920g252b

The really interesting thing about fermented foods is that EVERY single culture (often completely independent of each other) developed their own unique ferments. Many were also shared but have varietal differences. There are TONS most people have never heard about. It is really sad that with the advent of refridgeration we lost so many in common culture (many or most are still niche). And I am not saying fridges are inherently bad - we just should have also PRESERVED (get it? BADOOSH) these practices

Why is that interesting? It used to be very hard to keep foods. Fermentation is an easy way to do it. It would be much more interesting if it only sprouted a few times.

My Indonesian friend introduced me to tempeh, which has to be one of the most versatile (and healthy) foods. You can toast it for a quick snack, but it disappears into nearly every type of sweet or savory dish, or it can be the main attraction. I've put it into a meat red-sauce for added texture and protein. +1 would eat again.

Tempeh in Indonesia is great; it takes nothing like the tempeh I’ve had in the states. Admittedly I stopped trying over a decade ago because the disparity was so great. Can you finally get good tempeh in the US?

Anything I buy packaged is sad compared to fresh, home-made tempeh. I'd start looking at "alternative" grocers that also have fresh seitan.

seven different types, twelve methods of cooking...

https://en.wikipedia.org/wiki/Tempeh

I've never had Tempeh, but I love tofu, edamame, natto and other soy products. This is definitely on my list to try and explore the many varieties.

Was it LightLife tempeh? That's the kind I get. I've never had anything else, so I don't have anything better to ruin it for me.

I didn't know about most of these fermented soy products - https://en.wikipedia.org/wiki/List_of_fermented_soy_products

But Tempeh is a pretty common one for vegans. I've used it in curries and stir fries.

I think the problem is that Tempeh is always cooked, so I would expect any critters in there to be dead (not that they haven't done good work making it more digestible).

Indoles in general are common gut metabolites and an indole proprionate sounds like a further metabolic product.

This leads me to believe that trying to increase indole-3-proprionate specifically may be a fruitless journey (pun not intended), and one would be better off by optimizing for a hospitable environment for beneficial microbes in general, for example by cutting out carbs but increasing intake of flavonoids.

I suspect you may be right. Many supplements that have been tried just get broken down in digestion and don't actually increase target levels in the target tissues, rather we need to find ways of increasing the intake of precursor or figuring out which microbiota are involved in the metabolism and giving them a helping hand or just adding them altogether

I don't have a citation handy but I know eating fermented foods and increased fiber have both been linked to increased gut bacteria diversity. Thus seems in line with what the GP poster found for practical advice.

Its all about PREbiotics which are the food source for probiotics or your gut bacteria. Which encompasses some fiber and also sort of is its own thing. Long chain inulin and resistant starch are both some good ones

prepare for a whole new world. I started with a red fermented bean curd that had so many flavors that I stood dumbfounded while my brain tried to sort it all out.

Natto is amazing for SCFA (not specifically propionate though - more Glutamate)

I believe traditional salami also has a little propionate

I tried Natto and really really wanted to get to eat it every day. However, one portion gave me huge long lasting headaches. The flavour was good, and I am used to eat ferments (I make my own vegan yoghurt). I was really sad because Natto is supposed to have so many great properties.

Weird. Maybe try another brand? Some of them have weird sauces included too you can skip

Natto is also a great source of vitamin K2 (and I think the only vegan one).

By far the highest source of K2 out of EVERYTHING (like nothing else even comes close). Its truely great stuff for your stomach

Thanks for this. It's interesting how many of these studies reaffirm what we already knew. Eat yogurt, fruits, vegetables, nuts, etc. Avoid sugar. We might not have known why these were good for us but I've been seeing these "guidelines" for about 30 years now.

The "omega-6-heavy oils" makes me think of the work of Dr. Nemechek (https://www.nemechekconsultativemedicine.com/nemechek-protoc...), who works primarily with Autism. He found that a variety of brain injuries that of various types (including things like concussion), which historically have resolved themselves, have, in recent years, stopped healing. So a concussion that would have naturally healed a few decades ago, keeps giving the patient problems. One of his primary recommendations is to decrease the "omega-6 to omega-3" oils, because it seemed that omega-6 cause brain injuries not to heal. And it's worth noting that almost all vegetable oils (canola, soybean, etc), which are in almost all "processed foods" are high in omega-6.

This indole-3 link could be the reason why omega-6 oils are so bad.

TL;DR: Don't eat processed vegetable oils (other than coconut and olive oil).

Just be aware that that's a whole lot of conjecture with little solid evidence behind it. Saying "these brain injuries historically resolved but don't any more" sounds much more like a change in diagnostics to me.

The evidence against seed oils / processed vegetable oils is not very compelling yet (here's a pretty balanced summary: https://www.healthline.com/nutrition/are-vegetable-and-seed-... )

Am I misunderstanding your comment? Olive oil and coconut oil have terrible omega-6/omega-3 ratio, where as canola is pretty good.

https://www.cancerschmancer.org/articles/healthiest-cooking-...

If anyone goes through the citations here to find the explanation of how refined carbs (fruit, white rice/flour) and omega-6 oils detriment IPA production, would love to read about it.

I think it's coming from this source (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872783/) which more or less just generally claims that "Western Diets" are disruptive to gut microbomes.

Annoyingly, it doesn't really pin down what exactly it characterizes as "the western diet". It does include extracted oils and refined simple sugars (glucose and friends). But where exactly stuff like pasta/rice/flour sit is less clear in their description.

You can look up SAD, the standard American diet for a reference.

They displace food containing more fiber and by doing that change gut flora to that which does not produce IPA.

Fruit is not a refined carb...

I assumed that simple sugars count as "refined carbs" and simple sugars are found in lots of stuff including fruits. Btw, my hope is that this very restrictive diet actually isn't necessary for this metabolite.

By definition they aren't refined. You would have to remove the fiber to make those sugars refined as a first step. Fruit isn't pure simple sugars and it certainly doesn't act that way in the gut when buffered with fiber.

Genuine question that's likely to sound flippant: Does beer count as a "fermented food" in this context? What about wine?

I don't know the pedantic answer to "is that fermented food"

However, alcohol is quite an irritant and (along with caffeine) is the first thing a doc will tell you to cut out if you have intestinal problems

Speaking (only) from personal experience, it can be such an irritant that it more than outweigs the benefits of other probiotics and "good foods" -- even in small amounts (e.g. 1 drink)

There are also non alcoholic beers, which I have been exploring a bit. My favorite so far is athletic brewing's Run Wild IPA.

The study is behind paywall, does it say to eat it? The abstract just says delivery of Indole-3