Probiotics Survive Better with Some Fat: It’s the pH

If you haven’t noticed yet, a running theme/theory on this blog is the importance of pH in determining the microbial makeup of a person’s GI. The acidity level of one’s gut is what gives rise to particular species of bacteria, and I now believe it is the main determinant of whether one maximizes the benefits of supplementing with Resistant Starch and other fibers. The human gut is full of saccharolytic (carbohydrate-degrading) bacteria, and I believe what determines which ones get fed is pretty simple: whichever ones happen to be present. And again, it’s pH that largely decides that. If a bacteria is not adapted to a particular pH, it won’t survive, plain and simple. Like putting a human on a planet that doesn’t contain any oxygen. Now, this may sound a little circular — after all, it’s fermentable fiber that lowers pH. We’ll get to that soon, I promise!

For now, I wanted to do a quickie post that I think will give another angle on pH that I think is a little more tangible, since people are quite familiar with probiotics and fermented foods.

For a while now, I’ve been aware of research showing that the survivability of probiotics is greatly increased when taken with, or just prior, to a meal. And it is particularly the fat in the meal that increases the survivability. This study showed that quite clearly:

Enumeration during and after transit of the stomach and duodenal models showed that survival of all the bacteria in the product was best when given with a meal or 30 minutes before a meal. Probiotics given 30 minutes after the meal did not survive in high numbers.


The protein content of the meal was probably not as important for the survival of the bacteria as the fat content. We conclude that ideally, non-enteric coated bacterial probiotic products should be taken with or just prior to a meal containing some fats.

I hadn’t given this a ton of thought, until recently, when it occurred to me that the same pH principle applies here. The reason Lactic Acid bacteria (LABs) in probiotics and fermented food survive better is because of the pH buffering effect of food, and particularly fat. The stomach and its acids provide a very harsh environment for bacteria, as they should — that’s how we keep a lot of pathogens out. The stomach’s fasting gastric pH is about 1.5. That’s very low, even for the acid-loving LABs. What’s ideal? Broadly speaking, it looks like survivability grows and hits its peak at around a pH of 5. L. plantarum hits its peak at 4.8, in that study. And here’s a chart of L. plantarum growth in sauerkraut, which confirms that.




How does that line up with the effect of food on stomach acidity? Like so:

Humans secrete approximately 2.5 liters of gastric juice each day, generating a fasting gastric pH of 1.5, which increases to between pH 3.0 and 5.0 during feeding.

Well would you look at that. And when you look at how fermented foods are traditionally consumed, it makes perfect sense. Fermented dairy seems like quite a probiotic package, with its protein and fat content providing what is likely a pretty good pH buffer for LABs. And in the case of sauerkraut and kimchi, we know that these foods are traditionally consumed as condiments as part of larger meals that most often include meat and fat.

So it seems that if you are looking to maximize the effect of fermented food consumption it would be wise to consume some sausage with that sauerkraut, and some Korean BBQ with that kimchi.

More broadly, I think this illustrates what an important and universal principle pH is for the gut microbiome. What I found interesting in researching this was that among LABs, L. plantarum (who we’ve talked about quite a bit) seemed to be one of the most acidophilic. Which is in keeping with what’s been argued here — that L. plantarum is a pretty important commensal, and that acidophilia is a pretty good determinant of commensalism. Looks like L. plantarum is pretty well equipped to survive GI passage (but not without a little fat!).

And of course, LABs like L. plantarum seem to return the favor. If they can make it past that harsh acidic environment, their lactic acid production has a pH-lowering effect in the gut. We’ve gone at length about immunomodulation as the primary benefit of probiotic consumption, but I have to believe that this is a major benefit as well. But probably not to the same extent as fermentable fiber consumption.

Lastly, the effect of fat on pH lines up pretty well with the research showing the darker side of that effect — that meals with fat can increase circulating endotoxins, and that the consumption of fiber along with the fat negates this effect. In other words, this isn’t an excuse for a fat free-for-all. I’ve been running a personal experiment to test out this phenomenon, and it’s been quite interesting. I’ll post on that soon. In the meantime, I’ll leave you with Heisenbug’s corollary:

Eat fat. Always with plants. Sometimes the fermented kind.

— Heisenbug


38 thoughts on “Probiotics Survive Better with Some Fat: It’s the pH

  1. My wife thinks I am weird, but canned sardines or mackerel with kimchi has lately been one of my favorites for lunch. Guess I’ve been doing it right by accident.

  2. Thanks for the article. Always wondered how the probiotics made it past the stomach. Is there enough fat in fermented cod liver oil pills to get the probiotics past the stomach? I like to take all my supplements together and I don’t always take them with a meal. But I will try and change that.

  3. Hi there mr Heisenbug, thank you for this very intresting and easy to read blog!
    I can read on my samsung ipad, it’s great!

    I read up on L. plantarum today and found a very interesting study, if you haven’t seen:

    It seems that polyphenols in fact act as an prebiotic…that’s new to me.

    Well, just wanted to share with you all.

  4. whole rye bread, traditional corned beef, fermented sauerkraut, and some cheese. I knew this sandwich was good for me 🙂

  5. That makes total sense. Since I started the sauerkraut thing, Ive been looking for ways to make it more suitable for my taste. So since a week or 2 I put some in my lunch salad. Which contains always meat, fish or nuts of some sort and olive oil. Though it is maybe early to tell… but my hand eczema has vanished… gone… as in not there any more. An end to years of torture. I can’t believe it. The skin is still a bit dry and recovering from years of insane scratching, But no more itchy patches and night time finger scratching.

  6. Howdy. I have been taking PS and 3 kinds of probiotics (1 soil based) and includes the plantarum that was recommended for eczema. Been about a month on some probiotics, 2 mos. on RS. My eczema is gone on my hand and skin feels softer. (Hooray!) I also feel very, very well over all. I have a question I may have read something about either here or on Richard N’s site. I have eliminated gluten completely for over 2 years except for a few times when I willfully ate it. I am not celiac but sensitive–mostly in mood and brain problems, fog, depression, anxiety–I can certainly tell I have had gluten when I do, in other words. Last weekend I had considerable amounts (for me) of gluten. Cookies, buns, breading on fish and crackers. I have to tell you, I have had NONE of the symptoms I usually get with gluten after a couple of days of exposure. I feel exactly the same–great! Could improving my gut environment be helping me here? I don’t plan to go hog-wild on gluten but just questioning. I was LC or VLC Paleo for these past 2 years. Adding back safe starches have helped I think. I am not concerned about weight gain as I am pretty thin. 65 yo woman with no real health problems. I take no medication. Any thoughts? If this was addressed here before, I missed it.

    • Absolutely. Makes a lot of sense. Many of the leading celiac/gluten researchers believe dysbiosis is at the root of gluten problems. Fix the gut, and gluten may not be a problem any more. I’ve never believed that gluten/wheat itself is the problem.

  7. I usually have bacon and eggs with butter in the morning before I take a probiotic Is that a good “transit system”?

  8. Thanks for the post. Just a few days earlier, after coming home from work, I rummaged around for stuff to eat. Recognizing that I had not had sauerkraut for a few days, I ate 3 or 4 tbsp. But there was the last half of an apple left in my lunchkit so I ate it as well. Apparently that DOES NOT work in my body! My gut blew up so that getting to sleep was a bit tough. Note to self: ferments with fats!

  9. Wel whadda ya know, our grandparents did it right!! 🙂 The traditional dish in both Holland and Germany is: sauerkraut and sausage!! (Dutch: Zuurkool met worst. German: sauerkraut mit wurst).
    It has often been recommended to take our probiotics just before bedtime. Not a good idea if our pH is at its lowest. In future I will take my probiotics with a good tablespoon of coconugt oil, half an hour before a meal. In the UK you can get double cream, and there is a Marks and Specer store in Amsterdam, so I can take any probiotic with some double cream as well. (Good fat ssource)

  10. Thank you! Thank you for your research and your informative and easy to follow posts. I’m beginning to put the pieces of the puzzle together and come up with a plan to start healing my gut.
    The PS did not work for me: I gave it two long runs of about 2 months each. Then I read about the composition of the gut microbes after a round of antibiotics. Since I have taken antibiotics at least once a year for the past 30 years, the PS was probably feeding the bad guys. I have been supplementing with probiotics and homemade sauerkraut but alway taking them after fasting for 14 hours – gastric ph of 1.5. Keeping the ph high may be the clue I needed for re-populating my gut with the good guys.
    I feel as if I am in a car clue rally with the prized being better health and you keep handing out the clues. Thank you.

  11. Yes, I agree with Michele. The journey to optimum health does feel like puzzle pieces that fall into place after a lot of trying to force pieces that just won’t fit. If fasting is a really important piece for a variety of reasons, then surely the fasting effects of lowering the ph of the stomach to allow the beneficial bacteria entrance into the body is certainly a huge corner piece of the puzzle. Three quick questions: what is the minimum amount of time needed to get the ph lowered; does fasting lower the ph of the colon as well; and finally, from an anthropological perspective, if fasting has been with us as part of our evolutionary past, wouldn’t the advent of light after sundown whether being torches, campfires, light bulbs, etc., have started the more alkaline trend in our guts thereby altering our biome? More light after sundown more eating after sundown, less fasting, higher ph? I realize our diets in the West and antibiotics might be 100x more lethal, but wasn’t the trend started a long time ago? Thanks again for a great blog.

  12. is release of bile a good or bad thing in this context (survivability of probiotics)?

    just thinking…mct (medium chain triglyceride) is a fat which does Not require the release of bile for digestion.
    so would taking probiotics with mct oil be advantageous (or the opposite)?

    • to clarify further…
      so would taking probiotics with mct oil alone (and with no other fats) be advantageous (or the opposite)?

  13. Thanks for all of your work, Heisenbug!

    I’ve been taking my afternoon probiotics on an empty stomach in between meals. I’ll be changing this protocol to taking them right before lunch.

    We’ll see if that helps. I’ve added probiotics, as RS wasn’t working well alone – ongoing gas, bloating and fat-gain. Since adding the probiotics and backing off of the RS (limiting to little bits here and there), I’ve noticed decreases in the gas and bloating, and a stable weight (though I’m hoping to lose the fat I gained at some point).

  14. What’s with the time factor – before vs. after the meal? Stomach emptying is in terms of hours. Seems like if consumption of probiotics 30 minutes before was within the optimum timing, maybe something other than raising the ph could be going on? Especially if, as you mentioned, fasting gastric ph is especially low – taking probiotics during or after the meal should maximize buffering. Taking probiotics before food would seem to expose them to the lowest ph.

    Another thing fat tends to do is slow digestive transit. Could that be a factor? I wonder if their digestive model simulated transit rate change based on fat..

    Maybe consuming the probiotic early allows it to “lead the charge” down the digestive tract. And adding fat causes slow transit, allowing the leading bacteria more time to colonize.

    Maybe I’m barking up the wrong tree…

    • Good questions. But it’s definitely the buffering effect. The reason it works better just before or during the meal is a timing effect of the capsules opening. The probiotics are in a higher pH for a longer period of time. From the study:

      “The bacteria survival, when given before a meal, can be explained by the fact that the pH in the stomach remained higher for a longer period of time after the probiotic capsules opened (pH data not shown) due to the important buffering effect of the spring water and the saliva (Figure 3A). The saliva secreted in response to the intake of the capsules, taken with water, raised the gastric pH and then when the meal entered the stomach, 30 minutes later, the gastric content was further buffered. When the capsules were given after the meal, the number of bacteria surviving stomach and duodenal passage was greatly reduced as the bacteria arrived about the same time as the pH of the system began to decrease.”

  15. If an acidic environment is good to those little buggers wouldn’t it be a good idea to take probiotics with some vinegar or lemon juice?

  16. Hey, Mr. Heisenbug, I’m a long-time fan of your blog (well, for as long as it’s been around anyway!). I wanted to ask about one thing, but well you know, one thing leads to another and now I’m here to ask you about three things. Namely:

    1. In this post you outline why fat helps probiotic bacteria survive digestion. How many grams of fat do you think are necessary for this effect to take place (i.e. when does one start to see diminishing returns)?

    2. Coconut oil is said to have antibacterial qualities. For this reason, do you think that eating fermented vegetables as part of a meal with coconut oil (or coconut milk) would have a significant effect on how many bacteria survive through digestion?

    3. I believe I’ve read Paul Jaminet write that adding a large amount of sugary plants like carrots and bell peppers to a kimchi recipe can lead to there being more less-beneficial bacteria. It seems like a sure thing that sugary plants will ferment more rapidly, but do you have any idea about how this may affect the presence of different strains of microbes (or if they may really be ‘worse’)?

    Keep up the great work!

    • T.S. –

      I remembered your question when I came across some stuff related to garlic. If you do a pubmed search on “garlic probiotics” you’ll find studies suggesting (speculatively) that raw garlic inhibited some good bacteria just as it does pathogens. See the Booyens studies. However another study by Sutherland suggests some good bacteria, like l. Reuteri, thrive in a garlic environment. I don’t know the carryover to coconut oil, but it might be similar. This would be a neat thing to understand as I eat as much raw garlic as I can stand.

      • Do a google search for lacto fermented garlic and you’ll see that good bacteria use it as a food source, so it does not kill them.

  17. Nice sharing! I have seen another product which is also a very healthy probiotics. Keybiotics is one of the best formula that is having billion colonies of good bacteria. There are fourteen strains of good bacteria used in its manufacturing which makes it one of the most powerful Probiotics in the market.

  18. Very interesting. I simply don’t care for salty things at all like sauerkraut but I had heard about the importance of L. plantarum, so I took a teaspoon of Bubbies’ raw sauerkraut juice and then inoculated a glass of milk with it. It separated into curds and whey, and I used a teaspoon of the whey to inoculate a new glass of milk, and it continues to separate into curds and whey each time. I use it as an easy way to get L. plantarum into my diet without all the extra salt. I use whole milk, so it has fat. And I eat with a meal with more fat. It seems to work well. Like other people have said, my problems with eczema have cleared up.

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