Bacteria: How much is too much?

February 23, 2010 10:47 AM

I eat lots of yogurt and drink lots of kefir and kombucha. Do all these cultures live compatibly in my digestive system, or am I creating World War III in there?

I probably drink two servings of kombucha and two servings of kefir every day (not at the same time), and often one additional serving of yogurt. I don't feel any ill-effects, but I have to wonder what's going on in there now, and if I'm maybe canceling out the beneficial effects of the individual cultures I'm consuming. Anyone?

posted by hermitosis to food & drink (11 answers total)

Since the health benefits of eating these things are iffy (at the very best) to begin with, I wouldn't worry about it.
posted by paanta at 10:55 AM on February 23, 2010

You do know, don't you, that nearly all the bacteria you are consuming are being killed in your stomach by hydrochlorric acid?
posted by Chocolate Pickle at 10:57 AM on February 23, 2010 [2 favorites]

What your gut, an incredibly sophisticated evolved system with a dedicated neural network second only to your cerebral cortex, is doing to maintain its optimal health dwarfs the impact of relatively minor lifestyle choices like this. Your general diet probably has a greater impact on your intestinal microorganisms than the consumption of none versus one verus five food items containing live cultures does. Pretty much all folk probiotics is way speculative; eating probiotic foods (especially ones humans have been happily living with for centuries if not millennia) may well do some good and certainly no harm, it isn't worth worrying about.
posted by nanojath at 11:04 AM on February 23, 2010 [1 favorite]

The wikipedia article on yogurt suggests that there are health benefits related to the live cultures therein, so I'm not sure that CP is right about the bacteria getting destroyed by acid.
posted by Aizkolari at 11:10 AM on February 23, 2010

The fermentation really isn't an issue. Anything that can survive in your gut--which is one of the most acidic locations on the planet--is probably supposed to be there anyways, but dairy might be linked to acne. Two of those three things are dairy-based, so that's something to think about.

Besides, as has been point out, there's no real reason to believe that consuming active cultures is good for anything but repopulating the gut after a round of antibiotics.
posted by valkyryn at 11:12 AM on February 23, 2010

Besides, as has been point out, there's no real reason to believe that consuming active cultures is good for anything but repopulating the gut after a round of antibiotics.

It keeps up your immune response when you're stressed out, apparently.
posted by Greg Nog at 11:25 AM on February 23, 2010

You might want to watch out for dysbiosis or overpopulation of certain bacteria. Your gut microflora exist in a certain balance. Disturbing that balance for no good reason seems like an invitation to problems which you don't need.
posted by VikingSword at 11:58 AM on February 23, 2010

[few comments removed - maybe send kombucha recipes to the OP directly and focus on the question? thanks.]
posted by jessamyn at 12:53 PM on February 23, 2010

Lactobacillus acidophilus basically means acid-loving milk bacteria and it grows at pH levels lower than 5 (if my recent microbiology memory services). Belly acid doesn't necessarily kill it. The more alkaline environment of the upper GI tract may knock down some numbers, but by the time a (even small) population makes it to your lower gut, there's enough matter in there for the small numbers to get bigger before long. Benefits of endogenous flora in and all over your body are that they are innocuous and overcompete for resources against bad flora (bacteria, virus, fungus, etc). As far as health benefits beyond first-line immune defense as I have described, who knows. But anyone whose had a yeast infection or post-antibiotic diarrhea is likely just fine with the one well-documented benefit these kinds of bacteria have.

I am just a lowly pediatric nurse practitioner student in grad school.
posted by rumposinc at 1:02 PM on February 23, 2010 [3 favorites]

'who's had a yeast infection,' rather.
posted by rumposinc at 1:04 PM on February 23, 2010

Bacteria: How much is too much?

I had a GI Fellow tell me once that somewhere between 40-67% of your fecal output is dead and dying bacteria. So you see, your colon has a magnificent and persistent array of flora down there (accounting for fully 98% of the genetic variety found within your body). We catch most of our hundreds-to-thousands of species of gut bacteria from our parents or siblings during the first couple of years of life and the character of this turgid, adaptive biome remains remarkably resistant to fundamental alteration during our lives. It may be temporarily disrupted because of insults from potent antibiotics, sepsis and inflammation, or overgrowth, but it's amazingly good at restoring itself (given enough time). Differential patterns of metabolic activity of different clades of colonic biomes may account for as much as a 10% net calorie gain-vs-loss between two similar organisms fed the same diet (to say nothing of the various efficiencies of Vitamin K and cholesterol scavenging). Given that, how likely is it, do you think, that passing in relatively minute quantities of notably indolent strains of enzymatically restricted bacteria through the entire hostile length of your digestive tract will have much of a serious impact on your colonic biome?
posted by meehawl at 4:45 PM on February 23, 2010 [5 favorites]