Monday, April 21, 2014

Often acquired tastes are acquired genes: Probiotics and prebiotics

Gut flora is found in many areas of our digestive tract, particularly in the colon. Whenever we eat anything we feed the microbes that make up our gut flora and/or add new microbes. Much of this flora is made up of bacteria. Not all of it is made up of bacteria though. The much talked about Candida albicans (a.k.a. “the American parasite”) is a fungus that is found predominantly in our digestive tract and mouths.

Candida’s recent fame is more a testament to the power of well-orchestrated Internet campaigns to sell products than to the actual importance of the fungus in determining the health of non-immunodepressed individuals. Claims about Candida, including dubious ones, have been made many times in the past ().

The relationship between the human gut flora and health was a topic of much interest to Élie Metchnikoff (photo below from Wikipedia), who received the Nobel Prize in Medicine in 1908 for his research on phagocytosis (). Metchnikoff was also a pioneer in the study of aging.

Gut flora discussions often refer to foods and supplements that fall into one of two main categories: probiotics and prebiotics (). Probiotics are generally defined as foods and supplements that include health-promoting live microbes. Prebiotics are non-digestible foods and supplements that feed health-promoting microbes living primarily in the human colon.

Food fermentation, under the appropriate conditions, leads to the formation of natural probiotics. This applies to both animal foods (e.g., cheese, cured meats) and plant foods (e.g., sauerkraut, pickles). Prebiotics occur naturally in many raw plant foods as fiber and resistant starch, and can also be produced through starch retrogradation ().

Again, whenever we eat anything we feed our gut flora. This gut flora is reportedly made up of 10 to the power of 14 cells of bacteria, 10 times more cells than the human body (), plus other types of microbes (e.g., fungi). Different species of microbes in our gut have genomes that are markedly different from ours. Thus we carry in our gut significantly more genes than our own; and genes are selfish.

Genes are selfish in the sense that they seek to propagate themselves. From the perspective of our gut microbes, this can be achieved by inducing the secretion of chemicals that will make us crave foods that will also feed the microbes, whether this will lead to an improvement in our health or not. Even unhealthy human hosts can live long enough to sustain a large number of generations of microbes.

Killing the host human organism may seem like a suicidal strategy for gut microbes, but not if the host organism passes the microbes to other host organisms before the microbes themselves die. Microbes can pass from one human to another through many mechanisms.

So how can we improve our gut flora?

Supplementation or transplantation of microbes have been attempted with mixed but generally positive results ().

Few approaches combine the effectiveness and simplicity of avoiding highly processed industrialized foods. The emphasis here is on inhibiting the growth of unnatural gut flora; flora that has not been carried regularly by our Paleolithic ancestors.

Having done that for a while, which can be difficult due to cravings induced by unnatural gut flora, your own body may become very effective at telling you what is good for you and what is not.

As a side note, just because a food is fermented one cannot assume that it is health-promoting. Bread is a fermented food.

Over the years I have noticed that I prefer eating certain meat dishes cold, and several days after they have been prepared. I wonder if this has anything to do with a small amount of fermentation bringing to life probiotic microbes.


Charlie Currie said...

Very timely...the interwebs are all a buzz about gut health, probiotics - fermented or dirt - and prebiotics - especially resistant starch. And, resistant starch has the low carb world all a twitter, because we don't have a starch deficiency, you know! Ha

Richard Nikoley said...

"Having done that for a while, which can be difficult due to cravings induced by unnatural gut flora, your own body may become very effective at telling you what is good for you and what is not."

It's so hard it can be easy.

Same here.

dearieme said...

"I prefer eating certain meat dishes cold": which do you have in mind?

Ned Kock said...

For example, the dried mussels dish that I mentioned here recently.

raphi said...
This comment has been removed by the author.
raphi said...

2 assumptions:

1: We know little very little about what microbiota profile is advantageous or not
2: People are transitioning from a SAD-type diet

Hence this approach:

- "starve" current microbiota (likely via fasting or carbohydrate restriction) long? No idea.
- reintroduce pre & probiotics along with all-natural foods in a macronutrient composition of your long? which foods? No idea.
- observe changes & record them; rinse & repeat, rinse & repeat...

It seems like a sensible approach worth exploring. Any apparent efficacy in re-establishing a better microbiota/microbiome should also tried to be disproven.

How do you think this protocol/approach could be improved? Or should it be scratched all together?

Ned Kock said...

If one wants to replace flora component U (unhealthy) with H (healthy), it would make more sense in my mind to feed H and starve U at the same time – as opposed to starving U and H at first, and then feeding H.

Resistant starch consumption would feed H and starve U at the same time. Fasting and LC would starve U and H.

Does this make sense?

Ned Kock said...

The main target is flora in the colon, which RS would feed and stimulate to grow as long as a critical mass already exists.

If not, transplantation may be necessary, as probiotic ingestion tends to be more effective at switching flora at earlier points in the GI tract (e.g., small intestine).

raphi said...

To your first point, yes, starving U while simultaneously feeding H would be optimal. I didn’t propose it as I would be unsure as to how best achieve this IRL.

[Per their definitions] LC is not automatically an RS-deficient diet - but it can be. So can a high-carb diet. Why? Because RS is unabsorbed glucose (or most of it at least) and so are certain other types of fibers, hence it won’t technically affect the diets total absorbable carbohydrate load (leaving aside the caloric opportunity cost of displacing other foods).

Viable fecal transplant solutions are around the corner fortunately - it’ll be a whole different game and an easier at that hopefully!

far1a said...

Been reading some of your posts / articles and I'm liking them very much.

Up to age 25~ (im 28) "I was fed" mostly a carb diet, I've been battling tendinosis in some joints for 10 years... I still have them but they're much better and recover much faster since I switched to a low carb diet with no packaged foods, only meat,fish,eggs,fruits and vegetables. I also took a lot of antibiotics when I was a child because of sore throats/tonsils. Do you think all that made it possible for me to have some sort of auto immune disorder that attacks my joints to some degree? It also seems to have a strong correlation with computer use but some flare ups are independent of this. Also, when I sometimes eat plastic food or bad packaged stuff my girlfriend brings home I get strong stomach cramps.

If I don't get probiotics will the good bacteria eventually come back or do I really need to repopulate?

I've been doing 12-12 fasts with below 50 grams of carbs/d for two years and I must say I'm not the same, I will never go back as I feel so much better. I never get stomach cramps eating well but as soon as I eat a plate full of white rice I'm done... or bear or bread or pasta, I can only tolerate very small amounts... I also get some pimple like inflammations in my head that seem to be correlated... well with something...

I would appreciate your thoughts (or anyone's) very much, thank you. Keep up the good work!