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Friday, October 16, 2015

Does Heat Kill Probiotics AND Their Health Benefits? The answer might surprise you!

The short answer to the above questions is yes and no. Or at least, not necessarily. We'll have to unpack that a little. Raw foodies and paleo folks, hold on to your panties on this one, it might just blow your mind. 

I'll explain a little more about what probiotics and their benefits are below, but the primary focus of today's article has to do with heating probiotics, and whether or not that a) kills the beneficial probiotics and b) if heat kills the probiotics, whether or not they're still beneficial.

The full answer might surprise you :) And those who also dislike cold sauerkraut can rejoice, there is hope for hot bacteria yet...

So bear with me for a minute or two ladies and gents, we're about to do a teeny tiny bit of two things I like to call logic and science.

 The reason this is a two part article is because I don't always like cold sauerkraut or kimchi or miso. I'm also allergic to a lot of raw foods, and heating can sometimes destroy the allergen protein that causes an allergic reaction. Raw carrots and me don't always agree, but raw carrots - shredded in hot kimchi - and I get along just fine.

Furthermore, many probiotics food items - unless you make them yourself - come packaged, which often means they've been heated in order to seal the package.

Doing a little internet search pulled up a ton of websites that said YES! Heat kills probiotics and therefore you MUST eat it raw and not heated.

I wasn't convinced, however, that just because something is dead (in this case, those healthy little microorganisms) means that it also disappears. So if probiotics are dead, but not gone, can they not still do some good? 

What are Probiotics? 

By now many of you have probably already heard of probiotics, those healthy little microorganisms that are good for your gut and can be found in fermented foods like yogurt, sauerkraut, kimchi, miso, kombucha, and more. When we talk about probiotics in general we're talking about strains of Lactobacillus and Bifdobacterium.

Technically put, probiotics are classified by the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) as:

 "live microorganisms which when administered in adequate amounts confer a healthy benefit on the host" [1]

Where can you find probiotics?

Probiotics can be found in a variety of fermented foods and supplements, such as (and yes, I have some recipes linked below):

* Miso
* Sauerkraut

What are the health benefits of probiotics? 

In general, studies suggest that probiotics can be useful for helping issues like diarrhea, infectious diarrhea, lactose intolerance, allergies [2] and inflammation as well as potentially a host of other things that are still up for conclusive scientific review.

I get into the allergy aspect A LOT in my book Living with Oral Allergy Syndrome: A Gluten and Meat-Free Cookbook for Wheat, Soy, Nut, Fresh Fruit and Vegetable Allergies , but since this is an allergy blog, I thought I'd share another recent study in which researchers reviewed a variety of studies pertaining to allergies and probiotics and found that the majority of studies (17 of 23) "showed that people with seasonal allergies who took probiotic supplements or ate foods containing probiotics showed improvement in at least one outcome measure, such as improving their allergy symptoms, or their general quality of life, compared with allergy sufferers who took a placebo..." [3]

Does Heat Kill Probiotics?

Ok, so here's the first big question, right? Because if you throw some sauerkraut into your borscht, as I like to do in this Vegan Borscht recipe, or you want to toss some kimchi with your scrambled eggs in the morning, you want to know if you're killing all the good stuff, right?

The answer is probably yes. Probably. Because I haven't been able to determine at what heat different strains of probiotics are killed off. As far as I can tell, no scientist has put together a chart listing at what temperatures the various strains die.

So if you warm your kimchi in a pan, or bake your yogurt in a muffin, it may or may not die. This likely depends on the temperature, the item of food, and the particular strain of probiotics involved.

But here's the sticky point. A lot of websites out there will argue that, if it does die with the heat, it's no longer a probiotic, because the very definition of probiotic (as mentioned above) is a live microorganism.

However, as I said before, just because a bacteria (probiotic) is no longer alive doesn't necessarily mean it disappears along with its health benefits.

Here comes the good part...

It's called science.  

Well, okay, about as much science as a non-science person with no legal liability or medical training can provide. This is in no way medical advice, by the way, as I'm not a medical professional. See your doctor for questions! : ) 

Can heat-killed / dead probiotics still have health benefits?

( Get out your happy horns and party hats, cold sauerkraut-haters, you're gonna like this one.)

The answer, according to numerous studies, seems to be YES!! YES!! And sometimes, even heat-killed probiotics produced similar results to live probiotics. (Heat-killed being probiotics that have been killed by heating.)

I give you the science to prove that there is a good likelihood that heating probiotics, while killing them, does not necessarily destroy their healthy properties (in some cases, it may alter it for a different beneficial effect, or lessen it to some extent, but doesn't necessarily do away with it all together)

For example: 

* A study from 2009 in Pediatric Research found that the both the live AND heat-killed probiotic strain Lactobacillu rhamnosis GG (LGG)  ameloriated intestinal and other organ inflammation in infant rats[4]

* In 2010 researchers found that "many of the effects obtained from viable cells of probiotics are also obtained from populations of dead cells." Dead probiotics, such as bifidobacteria and
Enterococcus faecalis were found in different cases to stimulate the gastrointestinal immune system in chicks, and were beneficial to even healthy dogs. The article suggests that while live probiotic cells can be beneficial to gastrointestinal microflora, while dead ones could exert an anti-inflammatory response. [5]

* Another study found heat-killed Lactobacillus acidophilus effective at inhibiting bacterial Salmonella invasion of mouse organs [6] while another found that "lactobacilli can induce some (limited) protection (pro-biotic effect) against candidiasis in mice." [7] 

* A study on elderly people found that those who took heat-killed Lactobacillus rhamnosuswere significantly less likely to suffer from the common cold than those that took a placebo.[8]

So there you have it!! Just because something is dead doesn't necessarily mean it's gone.

This isn't to say there doesn't need to be more research done, and it seems that the benefits of heat-killed vs live probiotics might be different in certain cases. So it might not hurt to have some raw stuff AND some dead stuff from time to time.

But just like in my article on The Health Benefits of Raw vs Cooked Vegetables, sometimes science defies conventional logic (and raw foodies ;p ) and helps those of us who can't always have raw food.

What are some of your favourite probiotic foods? 
Do you incorporate them into other recipes?


[1] pg 9 of  this massive report on probiotics from FAO/WHO

[2] Kechagia, Maria, Dimitrios Basoulis, Stavroula Konstantopoulou, Dimitra Dimitriadi, Konstantina Gyftopoulou, Nikoletta Skarmoutsou, and Eleni Maria Fakiri. "Health benefits of probiotics: a review." ISRN nutrition 2013 (2013).

[3] The Weather Network quoting an article from Live Science

[4] Li, Nan, W. Michael Russell, Martha Douglas-Escobar, Nick Hauser, Mariela Lopez, and Josef Neu. "Live and heat-killed Lactobacillus rhamnosus GG: effects on proinflammatory and anti-inflammatory cytokines/chemokines in gastrostomy-fed infant rats." Pediatric Research 66, no. 2 (2009): 203-207. 

[5] Abstract for: Adams, Clifford A. "The probiotic paradox: live and dead cells are biological response modifiers." Nutrition research reviews 23, no. 01 (2010): 37-46

[6] Lin, W‐H., B. Yu, C‐K. Lin, W‐Z. Hwang, and H‐Y. Tsen. "Immune effect of heat‐killed multistrain of Lactobacillus acidophilus against Salmonella typhimurium invasion to mice." Journal of applied microbiology 102, no. 1 (2007): 22-31.

[7] Wagner, R. Doug, Carey Pierson, Thomas Warner, Margaret Dohnalek, Milo Hilty, and Edward Balish. "Probiotic effects of feeding heat-killed Lactobacillus acidophilus and Lactobacillus casei to Candida albicans-colonized immunodeficient mice." Journal of Food Protection® 63, no. 5 (2000): 638-644.

[8] Shinkai, Shoji, Masamichi Toba, Takao Saito, Ikutaro Sato, Mina Tsubouchi, Kiyoto Taira, Keiji Kakumoto et al. "Immunoprotective effects of oral intake of heat-killed Lactobacillus pentosus strain b240 in elderly adults: a randomised, double-blind, placebo-controlled trial." British Journal of Nutrition 109, no. 10 (2013): 1856-1865.


  1. That's really interesting. Thanks for sharing and for linking up with Annmarie and me for Meatless Mondays!

  2. Thank you for addressing this subject. I do eat kimchi with my eggs! I just add raw kimchi to my plate. When I do eat sauerkraut, I just slightly warm it up. I also like to mix other vegetables (cooked or raw) to the kimchi. So I don't think it's so bad if you eat slightly warm kimchi compared to if you cook it in muffins in the oven. That would definitely be exposing the good bacteria to higher heat temperatures for a longer period of time.

    1. I agree, I don't think that warming some things will necessarily kill the bacteria - yogurt needs to be slightly heated in order to encourage the growth of bacteria, and kombucha in a warm area will ferment much faster. And yes, I eat kimchi with my eggs too!! I just toss it in at the end to warm it for a minute. It's soooo good. I ate it so much recently my husband told me I was starting to smell like kimchi... guess it's time to cut back a little ;p

  3. That is great information, thanks for sharing with Hearth and soul blog hop, tweeting.

    1. Thanks for stopping by, Swathi, and hosting the Hearth and Soul Hop!

  4. Hi Danielle,
    I am glad you took the time to explore this question. I generally eat raw kimchi, miso, sauerkraut and yogurt for their probiotic benefits. I also drink kombuch and use probiotic capsules. Thank you so much for sharing this valuable information at the Healthy Happy Green and Natural Party Blog Hop. I'm pinning and sharing.

  5. Lactobacillus bacteria are the most common probiotics. They’re found in various types of food, including yogurt and sauerkraut. The strains of lactobacillus help with diarrhea and constipation.

    They restore digestive health and could be beneficial for the individuals suffering from irritable bowel syndrome (IBS) or ulcerative colitis.

    There’s some evidence that lactobacillus strains could reduce lactose intolerance in people who are allergic to dairy products.

    1. Thanks for sharing that, Nury. Some of the links I've posted above have information on the benefits of probiotics for diarrhea and lactose intolerance :)

  6. Taking probiotics will have a vastly positive impact on your digestive health. They’re great for overcoming problems like diarrhea and constipation. Probiotics will also reduce gas and flatulence.

    1. drinking anything warm, like warm distilled water also has a positive impact and its simple and clean. So smarten up - probiotics aren't everything.

    2. I don't think that anyone is saying probiotics are everything, only that they can be beneficial. On the other hand, I would love to see some scientific studies on warm vs cold water, as some people advocate for warm, and others cold, and yet I can't find any research on it...

    3. I think that it depends on your constitution. Do you know chinese medicine and Ayurveda? Some people need warm water, other cold, some even shouldn't drink so much of it altogether! It also depends on the season and the time of the day. Studies on a product can't tell us if this product is good for us, which is tricky because even if in western medicine it seems that we're all the same, we are actually very much unique.Studies help of course but there is much more work to be done...
      Samantha x

    4. Hi Samantha, yes I'm quite familiar with Chinese medicine - my father is a doctor of Traditional Chinese Medicine and I actually used to work in his clinic :) I still like to back things up with scientific studies when possible. I don't think the two practices need to be in opposition, as anecdotal evidence alone isn't always enough to definitively prove something.

  7. Probiotics are safe for kids but are they beneficial? Researchers haven’t done an awful lot of work when it comes to identifying the health benefits that little ones can experience from probiotic supplementation. Still, a couple of clinical studies provide positive results.

    1. I don't see why they wouldn't be beneficial for kids as well as adults, but I think if you can provide kids with probiotics through natural sources (i.e. yogurt, sauerkraut, kimchi, etc) that's probably preferable to supplements. Then again, I also think moderation in most things is best ;)

  8. An improved digestive system is worth having. No one likes to deal with gas bloating, constipation, and other problems. Yet, these problems won’t go away unless underlying issues are taken care of.

  9. Probiotic supplements or food make no sense if you understand what's going on. You're gut has 8 pounds of probiotics living there, with 300 different varieties. Adding a tiny pill, or even a pile of kimchi, is irrelevant. It's like adding a drop to a bucket full of water. Thus far, no benefit has been shown for probiotic supplements, other than a 19% reduction in gas for people with digestive issues, when using a single kind of probiotic. Now if you have coelliacs, ask yourself if a 19% reduction in gas is worth taking a supplement, when you could just watch what you eat instead.

    1. There are several studies that have had positive results for probiotic usage (I've referenced several above), but you're right that the jury is still out for definitively saying yes to certain health benefits - though there seems to be some positive studies for allergies, asthma, UTIs, and potentially IBS.

      If you have coelliacs or gluten intolerance, however, it's not as simple as just saying watch what you eat. There's always a risk of cross-contamination or mislabeling, and therefore getting glutenized and having your intestines and gut damaged. So is it worth eating some kimchi on the chance that it will help combat any gastrointestinal distress? I'm going to say yes for me ;)

  10. So the studies and findings mentioned here show that there are benefits to 'killed' probiotics, but doesn't conclusively show that they're at the same level of superiority with that of living strains.

    1. That's right. Some of them show similar or different benefits, but overall I think there's still a lot more research that needs to be done on probiotics in general.

  11. Allergies are caused by a faulty response of the immune system. It reacts to allergens – substances that the body views as threat and attacks. The symptoms of the allergy are an expression of this misguided defense mechanism.

    Many scientists are pushing a theory that focuses on the increased incidence of allergies in current populations. According to these scientists, excessive cleanliness leads to bacterial imbalances and an over-active immune system.

    1. Hi Margo, I'm not sure about excessive cleanliness necessarily being the issue, but the usage of certain chemical cleaners and air fresheners has been shown to aggravate allergies. I do get into bacterial imbalances and a variety of studies regarding the possible causes of allergies in my book, Living with Oral Allergy Syndrome. Factors such as the rise of pollen rates, pollution, exposure to certain chemicals, lack of certain vitamins, etc. have all been correlated with higher rates of allergies.

  12. You have to maintain healthy lifestyle to keep up with good health.


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