So you are sucking down the probiotic yoghurt, the carefully fermented Kombucha tea, and your prebiotic supplements? Why?
Okay, fair enough, you want your digestion to work better and you hope that improving your gut flora composition will improve this. But if you also eat a bunch of counterbiotic crap then you are basically just wasting your energy.
Today's rant sparked by Mark's Daily Apple: 16 Things That Affect Your Gut Bacteria and a bunch of other articles on the same subject. And a key note I saw in a gut microbe conference a couple of months ago (I only caught that one talk - it's a bit outside my field).
The thing that boils my piss is that everyone is missing the one factor that probably has the greatest influence on the composition of the gut microbiome (the bacteria that live in your gut and do all sorts of fabulous things for you). Food preservatives.
Food preservatives are specifically designed to kill bacteria or inhibit their growth. Not only that, they are selected to be most effective against the stuff that lives in humans naturally. So we shift the flora of the gut to these other bacteria that tolerate (and metabolise) sulphur compounds and probably some drug resistant bugs as well. It is not a good thing.
Food should be preserved by refrigerating, freezing, drying, pasteurising, or low pH. Or - call me crazy - eaten fresh.
Refrigeration is usually most helpful with things that have innate defences against spoiling. Apples can keep for a year or longer if very carefully stored (traditionally though you only keep them from fall till the end of winter). But it is brilliant.
Freezing is obvious. Not many bacteria are reproducing at minus 18. They can survive it though.
Drying is the same. When the water concentration goes below 20-25% bacteria and fungi are no longer able to grow. Honey is a great example of using low water content to prevent microbial growth in something that should be a feast for any bacteria or fungi. Things that look dry can still contain a lot of water though and condensation is usually enough to spur growth. Drying is the oldest method of food preservation known to man.
Pasteurisation is the process of heating and cooling food very rapidly so it doesn't cook but all micro-organisms are killed. The food is canned or sealed in some kind of pack (like a milk carton) to prevent micro-organisms from re-colonising the food. Although, if you cook things during pasteurisation it is more effective. It doesn't make for tasty milk or juice though.
Making something acidic is classic way of warding off bacterial contamination. This is usually achieved by fermentation, like in yoghurt. So there are actually micro-organisms in the food but they create a hostile environment for pathogenic and foul tasting bacteria. And the bacteria in a fermented food product produces many of the compounds that we otherwise depend on the bacteria in our gut to produce. Good stuff.
Now apart from possible competition from fermentation bacteria all of these preservation methods have no influence on the health of your gut microbiota. And the fermented foods actually (should) help your gut flora. Though the equilibrium of the species diversity in the fermentation wouldn't be identical to the equilibrium of the species in your intestines, it would still be in the same ballpark.
But artificial preservatives are still active when they hit your intestines. You've got benzoate, propionate, sulfur dioxide, sulfites, and EDTA as some of the major compounds. If you go to the Wikipedia page for preservatives EDTA is listed as an antioxidant but the fact of the matter is that it is an effective bacteriostatic and unlike other common metal ion chelators, like citrate, it is also not biodegradable. If you are worried about the ability of phytate to remove essential trace elements from your diet then you extension you should be terrified of EDTA. And just to freak you out even more - parabens in skin care products are absorbed by your skin and enters your blood stream which means they can enter your gut. So in addition to being endocrine disruptors they could also be gut flora disruptors. Just throwing that in there.
I like to think of these compounds as counterbiotics. They aren't antibiotics because they aren't effective enough to kill everything. They just shift the balance from a healthy, normal gut microbiome to something awful. Stay away from them.
"Ah, but surely that's pretty easy," I hear my over-used literary device, which I still don't know the proper word for, say. Well, it could be but in a lot of countries you don't have to advertise preservatives in things like fruit and vegetables. So dried fruit often has a butt-load of preservatives in them unless the packaging specifically says "No artificial preservatives". I have a soft spot for Crazy Jack's soft figs despite the pain in my cheap bastard heart for forking over that much for dried, rehydrated figs.
And if you treat food stuffs with chemicals to resist micro-organisms then you don't have to put it on any ingredient list. Since "a treatment" is analogous to milling or cooking or whatever. This includes things like ground meat (since you can mix that with Finely Textured Beef and pink slime is treated with antibacterial solutions) and flour. But flour is awful anyway. The world is just awful.
tl;dr Don't eat anything processed that you didn't process. Even if the ingredients ought to be paleo you basically can't trust anything processed that comes out of a supermarket. Because lawmakers hate you, that's why.