In several of my articles on fermented foods, I’ve stated that our preagricultural ancestors consumed primarily fresh foods, as opposed to fermented ones, and that I think we would be wise to follow in their footsteps. I strongly believe that people who harbor a dysbiotic gut microbiota can benefit from consuming small-moderate quantities of certain types of fermented foods, in particular fermented vegetables; however, I think it’s a bad idea to take in substantial quantities of fermented foods on a daily and indefinite basis. Part of the reason is that I think we’re inadequately adapted for such a practise.
In the comment section of one of my most recent articles on fermented vegetables, a reader challenged my statement regarding the evolutionary novelty of fermented foods. In this post, I thought I’d reply to his comment, which is shown below:
I would have to dispute that fermented products are evolutionarily novel.
While our hunter-gatherer ancestors may not have eaten sauerkraut or kimchi, a substantial part of their diet would have been raw insects and their gut contents: eat a raw locust, termite or mopani worm (a Southern African delicacy which now sells at three times the price of prime beef), and a goodly proportion of what goes into the eater’s gut is microbial ferment in the insect’s gut. Really interesting bacteria too – a large part of the insect’s diet is cellulose, which can only be utilised if broken down by bacterial action.
Bigger animals too: When a paleolithic hunter butchers an antelope, expect rumen contents (a bacterial ferment) to get over everything, especially the hunter’s unwashed hands and the raw or undercooked flesh that is eaten.
Thanks for the input.
Our hunter-gatherer ancestors would obviously have been exposed to a variety of microorganisms through the consumption of food.
What you have to keep in mind though is that the microbial ecosystem that’s found in the guts of animals differs markedly from the one that’s found in fermented foods like for example sauerkraut. Sauerkraut typically contains a narrower range of bacteria and is massively dominated by lactic acid bacteria, in particular Lactobacillus plantarum. The primary reason is that the number of nutritional substrates that are available for fermentation is very limited. Animals, on the other hand, typically consume a diversity of different foods; and hence, there will be a lot of different substrates available for microbes to “digest”. The microbial end products are obviously also going to differ.
In the human colon, for example, Lactobacilli only constitute a small portion of the total microbial ecosystem. Moreover, the primary microbial end products are short-chain fatty acids, not lactic acid, as in fermented foods like sauerkraut.
In nature, there is great inter-individual and inter-species variation in microbiota composition. That’s important to point out, as it means that someone who’s exposed to microorganisms associated with a diversity of plants and animals will be exposed to a great diversity of different organisms. The same cannot be said for someone who only consumes one or a few types of lacto-fermented fermented foods (e.g., kefir. sauerkraut, kimchi). Such foods vary with respects to their microbiota composition; however, they are all dominated by lactobacilli.
The consumption of raw animal intestines is in many ways more analogous to a fecal microbiota transplantation than it is to the consumption of fermented foods such as sauerkraut.
Furthermore, I question the statement that our ancestors took in a substantial amount of insects and foreign gut contents. Many of our ancient forebears undoubtedly ate insects (In general, hunter-gatherers eat what’s available to them in their local environment); however, I’ve never seen any evidence supporting the notion that insects made up a large part of Paleolithic human diets. Contemporary African hunter-gatherers such as the Hadza eat primarily larger animals, and I see no reason to think that the situation was substantially different in the past. Optimal foraging theory dictates that hunter-gatherers who go out into their local environment in the search for food want to get the most bang for the buck, in the sense that they want to maximize their caloric gain. Hence, it’s not surprising that they often go for larger animals over smaller ones.
Finally, as pointed out in the beginning, hunter-gatherers are exposed to a diversity of microorganisms through their consumption of food. However, I’ve never seen any evidence supporting the notion that it’s common for hunter-gatherers to ingest substantial quantities of fermented gut contents on a regular basis. Also, it’s important to remember that hunter-gatherers often (but certainly not always) cook meat prior to eating it, and in the process eliminate bacteria, as well as break down various heat-sensitive substances.
The bottom line is that hunter-gatherers are exposed to a very different mix of microbes and microbial metabolites than people who eat a diet heavy in fermented foods such as youghurt, kimchi, kefir, sauerkraut, and kombucha. Perhaps most importantly, they typically don’t ingest substantial quantities of just one or a couple of microbial strains; rather, they are exposed to a diversity of different types of microbes.
Please let me know if you have any further objections or concerns!