A Scientific Look at the Benefits of Probiotics
I’m concentrating on probiotics and fermenting for the month, and this is the first installment, here is an index I’ll add posts to as I publish them. I wanted to write an epic thorough post on probiotics, complete with scientific references and explanations. The problem is, that’s called a book. For now, please accept this truncated and incomplete version. I’ve tried to include ample sources to demonstrate that the immense importance of probiotics is not some hippy-feel-good theory, but grounded in science.
I’ve long known that ‘probiotics’ were good for you in a general way, hearing advice to take them after antibiotics. We are, however, discovering functions of probiotics that are actually fundamental to our well being, as opposed to being a nice thing to have. Studies and experiments are continually discovering new ways that these little bugs benefit the human host and I think we are just starting to uncover the tip of the iceberg.
Probiotics are mostly bacteria, with a few kinds of yeast, that populate our bodies. We tend to concentrate on the ones that reside in the gut, but beneficial bacteria are also present on all the places of contact with the ‘outside’ world, including skin, eyes, genitals, and breastmilk. For our purposes, we will focus on beneficial flora in the gut.
Technically, probiotics are defined as “live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host” by the World Health Organization. This definition is mostly in reference to supplements and advertising claims, so that ‘probiotic’ on a label must have scientific evidence of some health benefit from the strain of bacteria or yeast that is being promoted. With an estimated 1000 species of beneficial flora residing in or on the human person and however, there is much more research before all the health benefits that do exist are found out. And of those 1,000 species of beneficial bacteria in the human ‘eco-system’, each of those species has multiple strains, each of which can have a different influence on the human host.
As an example of how much we don’t yet know, the second most common bacterial species listed in the American Gut Project ( a project examining swabs/samples from a variety of people mostly in the United States) doesn’t have a name – in fact, it doesn’t even have a named genus. And the most common bacteria mapped by the American Gut Project is practically non-existent in the Hanza tribe of Tanzania, a group still living a hunter-gatherer lifestyle. This study, as well as other, indicates that the composition of an individual’s microbes is dependent on that individual’s diet.
One way of categorizing probiotics is if they are resident or transient. Some probiotics are permanent, colonizing in the gastrointestinal tract and staying. Transient flora, on the other hand, are usually eaten and eliminated, although some colonize temporarily in the gut. Even though they are temporary, the bacteria still perform valuable functions and may even enhance the performance of the resident flora. The fact that beneficial flora are transient points to the importance of consuming probiotics on a continual basis.
Benefits of Probiotics (heavily relied on this article)
Although using the generic term of probiotics when listing the benefits, each benefit is influenced by a different strain, never mind species, of beneficial flora. There is evidence that there is some overlap, or that some types of probiotics can change their function based on need, but taking a general probiotic supplement or eating only one probiotic food (like yogurt) will not have the effect of conferring all the listed benefits of probiotics.
Some of the more obvious benefits of probiotics are related to the gastrointestinal tract, given that that is where they reside. Probiotics release enzymes, which help break down food and make it more available for the body to absorb and use.
Probiotics also have an effect on elimination, correcting both diarrhea (from various causes) and constipation. They can heal diarrhea by getting rid of pathogens by releasing specific bacteriocins (something like an antibiotic), creating an inhospitable environment, competing for space, strengthening the immune system, and increasing mucins (a component of mucus) that prevents pathogens from attaching to the intestinal wall. As for constipation, certain probiotics can increase peristaslis activity (the squeezing of the digestive tract to move food along).
Probiotics can synthesize vitamins, most specifically vitamin K (necessary to blood coagulation and utilization of calcium) and some B vitamins, most notably riboflavin, folate, and B12.
Probiotics have an anti-inflammatory effects, both on the gut and in other parts of the body. One study found that one bacteria helped across a range of inflammatory diseases: ulcerative colitis, psoriasis, and chronic fatigue syndrome. Given the breadth and prevelence of chronic inflammatory conditions, including insulin resistance, atherosclerosis, rheumatoid arthritis and neurodegenerative diseases, the idea that a probiotic can reduce inflammation in the body has exciting potential.
The gut is actually responsible for about 70-80% of your immune system. That means that your ability to fight off the flu virus, the bacteria from a sneeze, and other harmful pathogens depends on the strength and health of your gut. The health of the immune system also relates to the increasing occurrence of autoimmune diseases.
In the lining of the digestive tract exist a large number of immune cells, which are transported throughout the body via the circulatory and lymphatic systems. Probiotics strengthen the gut wall (the epithelial cells), thereby strengthening the barrier guarding against pathogens penetrating the gut wall.
As well, probiotics increase the acidity of the digestive environment, which kills off many pathogens. They also can influence how some immune cells to suppress inflammation. (More on gut immunology.)
Food Allergies and Eczema
Food allergies rose a whopping 50% between 1997 and 2011. Allergies happen when the body identifies a molecule, such as from peanuts or milk, as harmful to the body and start attacking it. Evidence is building that food allergies and intolerances are probably due to ‘leaky gut’, or when the barrier of the intestinal wall is not strong enough and the offending molecules slip through into the blood stream. Probiotics can help in multiple ways, by releasing enzymes that help break down food, by strengthening the barrier of the gut, and reducing inflammation. As some skin conditions like eczema are a result of internal reactions to particles, probiotics can help with eczema as well.
Urinary Tract Infection
Common knowledge links probiotics with bladder infections, however, only a few specific strains have colonized in the urogenital area in clinical studies, and those specific strains are only available commercially in Austria. All the products that claim to populate the area with probiotics may not be effective. General probiotic health will help UTI’s by improving the immune system and reducing the number of pathogens in the digestive tract (which can infect the urethra via the rectum). Studies have had some success with probiotics and vaginitis as well.
Babies and Birth
It has long been thought that babies are in an germ-free environment in the womb and have their first exposure to bacteria when coming through the birth canal. A recent observation that bacteria are present in meconium, a newborn’s first poo, led to a study of the microorganisms of the placenta. They discovered that the placenta harbours a microbiome most similar to those found in the mouth, and that some of those microbes cross from the placenta to the baby. Despite this new information, the birth canal and breast milk continue to be important sources of probiotics, although the birth canal could expose the baby to harmful bacteria as well. There is some evidence that the types of resident bacteria do not change after toddlerhood, so this increases the importance of parents’ having healthy microbes (the mother for obvious reasons, the father as he influences the microbes of the mother through contact) and raises the question of inherited health problems, not via genetics but via handed down microbes.
Other studies have been done/are being carried out to determine the effect of probiotics on health problems such as cancer, blood lipid levels, HIV, and oral health. Probiotics can also affect sleep (this blog is fascinating)!
One more area of interest is the microbiome-gut-brain connection, which basically means the relationship between the microorganisms living within the body, the health of our gut, and our mental health. I will, however, leave that to it’s own post.
If you find this article helpful, please leave a note! I know it doesn’t look like much, but researching a topic is very time consuming and brain challenging, and if it doesn’t benefit anyone I’ll just post recipes. 🙂
Have you used probiotics to benefit your health? How did they help?
Shared at Fat Tuesday, Pennywise Platter Thursday, Real Food Wednesday, Allergy Free Wednesday
Oct 07, 2014 @ 15:48:44
I’m fascinated by all of the research done on our microbiomes, especially considering the effects of heavy antibiotic use in our culture (which, frankly, has probably thrown off far more people’s microbial balance than has poor diet). I like that it fits with older and now outdated research on the “hygiene hypotheses” (outdated in that now we realize that contact with many different kinds of bacteria in youth probably helps by supporting bacterial colonization rather than by training immune response the way we once thought). I like that the link with antibiotic use makes sense of the rise in autoimmune disorders and allergies in first world countries compared to the rest of the world. I like that it’s not a simplistic explanation of any of these things, given the complexity of these bacterial ecosystems.
I don’t do a lot of cooking and food preparation outside of a few old favorites because I have picky kids and very little time or patience in the kitchen, but I do enjoy your posts on non-cooking stuff, so please do continue with them. 🙂
Oct 08, 2014 @ 14:22:58
It’s interesting that there are much fewer allergies in Slovakia than Canada and the US, although of course that number is rising. My SIL’s mom, who is in her 40s, said that when she was a kid fermented cucumbers were the best treat ever, they sold them at swimming pools and all sorts of small stands, similar to popcorn. It makes me wonder if part of the ‘behindness’ allergies and autoimmune conditions has to do with the fact that fermented foods have been used in more recent history. And, many people in towns used to have animals (pigs and chickens) even though they weren’t farmers properly speaking so children would have been exposed to more bacteria. Anyway, yes, it is fascinating and very complex!
Trust me – the only thing I manage in the homemakers way is cooking. Thanks for the note 🙂
Oct 07, 2014 @ 18:58:32
Thanks for the details. Also interesting that many who need extreme healing, having leaky gut, are actually allergic to probiotics, especially lactobacillus. Antibiotics weave a complicated web of healing. 🙁 Cheers & thank you for your work!
Oct 08, 2014 @ 14:25:53
Ironic, isn’t it? I thought it was bifida probiotics that were problematic, not all lactobacilli?
Oct 07, 2014 @ 23:11:38
wonderful info!! I know you put a lot of time and thought and research in this article! I am particularly intrigued bc I have developed a patch of sudden onset eczema on my face, and I want to get to the bottom of it! Strangely clinch dental (?), I started a new probiotic supplement a couple weeks before noticing this and I have never ever had problems with ecZema in the past. I will ferment my way back to health hopefully and your blogging comes at a great time!
Oct 08, 2014 @ 14:27:08
Thanks 🙂 Perhaps ease back on the new probiotic (take 1/4 or something) and slowly increase it?
Oct 07, 2014 @ 23:12:30
Strangely coincidental, not clinch dental. :/
Oct 08, 2014 @ 00:40:10
Our bacteria fascinate me – this information is so important. Thanks for sharing!
Oct 08, 2014 @ 14:27:46
Thank you! It is fascinating – it almost makes me want to be a science writer…until my brain starts hurting.
Oct 12, 2014 @ 21:38:11
Thanks, Naomi! It is very interesting for me, since I have recently come to the conclusion that probiotics can heal me. I am dealing with a minor stomach inflamation, that is making my life (digestion) really problematic at times. But when I take probiotics regularly, it’s much much better… And your research was very interesting. Thanks! I am looking forward to reading more!
Oct 13, 2014 @ 17:01:55
Thanks Maja! I hope probiotics help heal your digestion! Try out some of the fermenting recipes coming up for fresh probiotics!
Easy Homemade Sauerkraut Recipe - Homemade Probiotics
Oct 31, 2014 @ 21:20:58
[…] to mental health. There are too many benefits of probiotics to list here, but I’ve written A Scientific Look at the Benefits of Probiotics, which is full of references to a slew of […]
Jul 30, 2017 @ 07:48:35
With what little i know about fermentation I have become fascinated the help it does to our whole body. I love it, thank you for sharing!
Jul 30, 2017 @ 21:55:29
Glad you enjoyed it and found it interesting. I find it fascinating too!