Gut microbe linked to depression in large health study

We know that microbes colonize the gut in a somewhat predictable way as a function of age. As a newborn your gut is largely dominated by Bifidobacteria, and this slowly transitions to a more complex community over the next several years of life. Events like early childhood antibiotics, malnutrition, other disease, etc. can alter this trajectory. Interestingly this kind of ecological succession seems to be driven by an interplay of both immune maturation (as your immune system matures it starts being more selective about who it tries to let in) and by chemical processes. The gut becomes more anaerobic as the number of bacteria increase (and transition away from the Bifido dominated state) and that has a strong selective effect on the microbes that will grow well.

For specific commensal bacteria we know some of the mechanisms of colonization - there are particular genetic programs that bacteria turn on when they sense they are in the gut to enhance their ability to be retained and not washed out. These programs include physical attachment, motility, and chemical signalling to try to dampen the local immune response.

Pathogens are extremely good at getting in to the gut despite our best attempts at keeping them out. Salmonella typhimurium is notoriously adept at colonizing the host - the infectious dose you need is maybe 10 microbes taken orally in a susceptible host (compare that to 10 billion microbes/capsule in a probiotic).

For these specific bugs I don't know that much. I am excited to read more.

Yes exactly this.

> Especially since I think it'll be interesting to find out if something has been added to our diets that's causing an increase in intolerance over the last decade+.

One thing I read is that western diets severely lack in fiber which usually leads to loss of microbiome diversity [1]. But studies like this are still early stages, we need targeted results based on all this to really have any effect.

[1] https://nautil.us/how-the-western-diet-has-derailed-our-evol...

Look up nutritionfacts.org and read/view it with a generous pinch of salt. A few years ago it took me half a year to switch to a mostly WFPB diet advertised there and I had no issues whatsoever. My gut is now more resilient, I remember having problems with bloating and/or diarrhea if I ate just a bit more fiber some days.

> why aren't we focusing on making healthier decisions for our diet, exercise, and mental well being?

The answers are there, but cognitive dissonance prevents us from recognizing or accepting them.

My best guess for what happened is that work stress, excessive celebration and coping with the cognitive dissonance of the pre-COVID era and subsequent pandemic, combined with overtraining and the misuse of protein shakes in place of food, left me in a chronically dehydrated state. The body tries to collect moisture from the gut, which opens an opportunity for bacteria to get into the body cavity and blood, which is colloquially called leaky gut. This sets off food sensitivities and eventually an autoimmune condition/response to lectins, gluten, etc, which have proteins similar to linings in the body, joints and thyroid. Then a cascade happens where everything goes out of whack quickly. In my case, I went from being in the best shape of my life, the strongest I had ever been in the gym, to barely able to get out of bed in the morning. In other people, it might present as chronic fatigue, arthritis, etc.

I didn't really believe any of this in 2018, and my meal plan then consisted entirely of everything that I can't eat today. So I consider what people say politely, but for the most part, they have absolutely no idea what they're talking about. This experience has made stuff like GMO foods sound absolutely insane to me. Like, why would we ever taint our food supply to make food 5 cents cheaper or "feed the world" when we've been operating under artificial scarcity since the end of the second world war? It's all a crock.

Every time you eat inflammatory food, the risk is similar to smoking a cigarette. Probably nothing will happen, but if it sets off your immune system, you may wake up one morning chronically depressed and/or unable to eat something that you rely upon. It got me after I turned 40, YMMV.