News next - This post will most likely be the last one for a week or more, though I'm updating a couple of older posts for Psychology Today and may post a link tomorrow. I'm on vacation. Whew.
Update on the July Whole30 - finishing up Day 14, and the main thing I'm finding is that it is difficult to eat quite enough. I've lost a dress size (and I'm not trying to restrict calories), but can be a bit cranky before meals, and after the first week I've not been particularly hungry. Though I love the freedom and convenience of rather frequent intermittent fasting, it has also been nice to simply eat three meals a day and throw in an extra banana, some berries, or a few macadamia nuts for snacks. No "cheating" except for a half teaspoon of honey in tea on Monday morning (I had a good reason for it). All cravings for chocolate and Diet Coke were pretty much done by the end of the third or fourth day. The honey ingestion didn't reawaken any of that.
Vacation will up the ante. It will be difficult to be eating out at restaurants all the time and be as sure as one ought to be in the Whole30 about ingredients. We'll see how it goes. I'm not going to throw in the towel if I realize something is screwed up, and will likely just try to order steak as much as possible. Veggies may be difficult as they are usually cooked with butter or covered with soybean-oil based salad dressing.
Now the paper! This one is on the hypothetical side - all tell, no show, but rather fun. I believe Chris Kresser tweeted it to my attention, or it could have been Dallas and Melissa. Both of them sent me probiotics papers so thanks to both!
Ahem. Probiotics function mechanistically as delivery vehicles for neuroactive compounds: Microbial endocrinology in the design and use of probiotics.
The down-low is that probiotics are thought to modulate the production of inflammatory particles (cytokines), affect the adhesion of pathogens to the gut mucosa, and other groovy things. However, no one really knows how they do what it is that they do. There are now several studies with intriguing evidence that probiotics can affect the brain (one of which I wrote about earlier this week). One study even showed anxiety reduction in human volunteers (and mice) with administration of Lactobacillus helveticus and B. longum. Again, since disorders that affect the gastrointestinal tract seem to co-exist quite frequently with anxiety, depression, and other mood disorders, probiotics and gut health may have "profound clinical implications."
There is a great deal we don't know. Many of the organisms can't be cultured. It's difficult to study the secret life of the wee beasties while the host is walking around doing the day to day. There are zillions of varieties of beasties, and typically the probiotics used for studies depend on what company is supplying them rather than a more specific rationale or knowledge of the effects of each species.
So what, exactly, do we know? As far back as 1929 it was discovered that human carriers of certain Clostridium species who were given epinephrine to treat hives died suddenly of gas gangrene (oops). For 60 years, it was thought the epinephrine somehow suppressed the immune system, leading to the sudden fulminant infection. In the early 1990s, however, it was found that yes, indeed, gut bacteria could respond directly to human neurochemicals (such as epinephrine). It has been further proven (with the flurry of recent papers) that the communication between the beasties and the brain is a two way street. Neurochemicals are highly conserved in evolution - bacteria, plants, insects, and fish all produce forms of the neurochemicals called the catecholemines. Thus it makes sense that bacteria in our gut can communicate directly with using, to some extent, the same "language" as our mammalian brains.
Lactobacillus and Bifidobacterium species are known to produce GABA. Escherichia, Bacillus, and Saccharomyces produce norepinephrine. Candida, Streptococcus, Escherichia, and Enterococcus produce serotonin. Bacillus and Serratia produce dopamine, and Lactobacillus species produce acetylcholine. That's pretty much the entire hit parade of major neurotransmitters (there's histamine and glutamate and a few others - and histamine is known to be produced by some bacteria that infect shellfish, for example, causing food poisoning).
The most interesting case here is GABA, the major inhibitory neurotransmitter in the nervous system (it chills things out) - and there are whopping amounts made by the bacteria in fermented foods, and is also found in yogurt and typical probiotic capsules. GABA also turns out to be anti-inflammatory in the gut itself, decreasing the release of inflammatory cytokines. Thus there is a plausible mechanism by which certain probiotics could decrease inflammation and aid symptoms of conditions such as IBD or IBS, and, considering the vagus nerve and all it's tendrils in the gut, have direct communication via the neurotransmitter GABA to the brain.
The author of the paper outlines some straightforward methods by which the individual effects of the probiotic species could be systematically characterized and studied. He has developed a framework for the promising new field of microbial neuroendocrinology. Of course his interest is along the lines of mining microbes for human use - it seems to me our ancestors and their fermented traditions have been mining microbes for these uses for some time, without all the species typing and science.
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