What is a Probiotic? Guide to Foods, Supplements, & Benefits
By Ali Kuoppala | Last reviewed Tue 25 September 2018
Medical Review by Gerardo Sison, PharmD
Those red turd-looking things above are probiotic microbes from the Lactobacillus family of bacterial strains.
They are just a tiny part of the 100-trillion bacteria that populate your gut. And no, that's not a typo, there are in fact 100 000 000 000 000 living microbes in your tummy.
That's 10 times as much as you have cells in your body, so technically speaking, you're not a human, you're just a giant pile of bacteria (sorry).
These live organisms in the gut have extremely important processes in your body, and they impact your immune system, brain function (yes, nerves connect the gut to the brain), hormone production, and obviously play a central role in the health of the gut (digestion and the like).
What Exactly is a Probiotic?
In the early 20th century, a Zoologist by the name of Élie Metchnikoff pioneered the research on gut health, bacteria, and immunity.
One of his first realizations was that Bulgarian peasants who lived in extreme poverty and could only afford cultured yogurt to feed themselves with, actually lived far longer than the people that were well of and didn't eat nearly as much fermented foods.
This eventually led him to figure out that fermented foods contained good types of microbes (probiotics) that were able to colonize the gut and have significant effects on immunity, overall health, and digestion. In recognition of his work, Metchnikoff was awarded the Nobel's Prize in 1908 and is now remembered as "the father of natural immunity.
It wasn't until 1965 that the actual term "probiotic" was coined to describe these type of live microbes found in certain types of fermented foods and the guts of humans and animals.
So what exactly are probiotics?
The simplest definition comes from the British microecology expert, Roy Fuller, who defined probiotics in 1989 as:
"live microbial feed which beneficially affects the host animal by improving its intestinal microbial balance"
In other words, probiotics are the good bacteria, used to repopulate and colonize the gut, replacing the harmful microbes with beneficial microbes in the gut flora, resulting in a whole host of health benefits.
Probiotics Benefits and Research
The list of scientifically proven benefits of probiotic administration that has slowly accumulated over the last 100 years is staggeringly awesome.
Whereas the main benefit of probiotics is without a doubt related to gut health and immune system function (believe it or not, 80% of the immune system actually resides inside the gut), there are also some surprising benefits to overall health and hormone production, even brain health, intelligence, memory, and mood...
...Here's some of the most interesting benefits of probiotics;
- Significant improvements in people with ulcerative colitis and inflammatory bowel syndrome (IBS).
- Stimulation of the production of T-cells which are key players in immunity and fighting off virus-infected and tumorous cells.
- Necessary co-factor in the production of vitamin K2, vitamin B-12, and folic acid in the gut.
- Significant reduction of constipation and length of diarrhea symptoms due reduced inflammatory response and recolinization of the gut flora.
- Increased testicular size, sperm production, testosterone levels, and the levels of gonadotropins that stimulate T production in male rats.
- Reduced symptoms of central nervous system disorders such as: anxiety, depression, autism, and OCD.
- Improved cognitive functions, especially memory formation and retrieval. The exact mechanism still being unknown.
- Reduced stress-response to danger with accompanied improvements in escape-learning in rodents, possibly through GABA-modulation.
Foods High in Naturally Occurring Probiotics
Some foods contain naturally occurring probiotics and live enzymes.
This list almost exclusively contains foods that are fermented using strains of microbes, sugar, or yeast.
Pickled foods are also made by fermentation and have small amounts of probiotics in them.
Many rural and/or traditional cultures ferment majority of their foods, be it dairy, grains, beans, fruits, fish, and even meats. This is believed to be one of the key reasons why they tend to be more healthy (despite having no access to modern medication) than us Westeners.
Here's some great natural sources of probiotics;
- Kefir - the mixture of fermented milk and kefir grains is one of the most well-known sources of probiotics with more than 3000 years of recorded history of its use. Contains anywhere from 10 to 35 strains of probiotics.
- Yogurt - there are many different types of fermented yogurt coming from different milk-giving animals living in different conditions, eating different kind of foods. Best is organic grass-fed sheeps or cows milk yogurt.
- Sauerkraut - Being fairly high in digestive enzymes, probiotics, and vitamin C, sauerkraut is one of the greatest digestive and gut health foods. Its popular in Germany and even studied for its beneficial effects.
- Raw cheese - Made with fermentation, many types of cheeses are rich in digestive enzymes and live probiotic cultures. The thing is that it has to be raw cheese for you to get these benefits, as pasteurization kills probiotics.
- Kimchi - Made by mixing ingredients such as Chinese cabbage, red pepper, carrots, radishes, ginger, garlic, onion, fish, sauce and salt. This distant relative of Sauerkraut is then fermented for 5-15 days.
- Kombucha - For around 2000 years, Kombucha, a type of yeast and probiotic fermented black tea has been consumed in Japan and rural Russia. This habit has slowly made it to Western world too.
How to Choose the Right Probiotic Supplement
Like said few times already, not all bacteria is good. And with that, I'd like to tell you that not all probiotic supplements are good either.
You've probably seen how many brands bolster with claims like: "Highest amount of CFUs (colony forming units) on the market! Over 50-billion live bacteria!"
That's cool and all, but it isn't really a big deal how much of the bacteria the product has. It's what bacteria is in the product that truly matters.
If the goal was to just get a lot of bacteria into your system, you might as well eat dirt from the ground.
Instead of being obsessed about the amount of bacteria, look for specific types of strains like these:
- Bifidobacterium longum- One of the early habitants of the gut of infants, B.longum prevents the growth of pathogenic organisms and is a crucial part of natural human gut flora.
- Lactobacillus acidophilus - Occurs naturally in the mouth and gastrointestinal tract of humans and animals; known for its effect in converting sugars to lactic acid and decreasing the amount of toxins in circulation.
- Lactobacillus rhamnosus - Chain-like probiotic strain with very interesting effects in regards of preventing stress response and suppressing cortisol levels via the GABA-receptors of the brain.
- Lactobacillus casei - Found in many dairy products and one of the most well-known probiotics. Necessary for carbohydrate digestion and works to prevent the incidence of "leaky gut" in presence of gut inflammation.
- Bifidobacterium breve - The most prominent type of bacteria of the human gastrointestinal tract. Most notably known for its effect in reducing constipation and improving metabolism.
- Lactobacillus reuteri - Commonly colonizes the guts of healthy humans and animals. Has been shown to significantly increase testicular size and testosterone levels in male rodents.
- Bifidobacterium infantis - Works by better utilizing carbohydrates in the gut, but also researched for its effects in significantly relieving symptoms of irritable bowel syndrome (IBS).
Probiotics Side Effects and Safety
Probiotics are generally very safe, if you consume the strains above and/or get them from the listed foods.
Obviously not all of the thousands of different types of bacteria that we can be exposed to and already habit our gut, are actually healthy or beneficial.
So when it comes to general safety of probiotics, there are two main concerns to keep in mind.
- Always consume probiotics supplements with only the strains you need and know are well-researched and beneficial for you.
- Never buy from shady manufacturers who don't list the actual strains and/or only market their product with the total amount of microbes.
I'm talking about things like gas and bloating, which naturally occurs during the transition period where your gut flora is being recolonized with new bacteria, and the not so beneficial microbes are getting replaced.
These symptoms are not very common, and they are most certainly temporary, but it's important to understand that in most cases that's just a natural response to the changes happening in the gut flora, rather than a sign of something bad.
Common Factors that Kill Probiotics
One of the most crucial factors in improving the health of your gut and maintaining beneficial strains of bacteria in its flora is eliminating factors that destroy probiotics.
You don't just want to recolonize the gastro-intestinal tract, you also want to make sure that the bacteria survives and that there's always more of the good kind.
You want to have balance, and the majority of the digestive health experts agree that this means roughly 85% beneficial bacteria and 15% of the so called "bad bacteria".
Why not just have all good bacteria?
The common theory is that when you harbor small amount of pathogens in your system, your body actually develops natural resistance towards them and handles them more easily, similarly to the new studies which have seen that kids living in overly clean conditions are actually far more sicker than those who live in more "dirty" conditions.
It's when the growth of the bad bacteria gets out of hand that you get the negative health effects, this is often described as "dysbiosis".
Anyway, here are the common factors that kill good kinds of probiotics and may lead to imbalanced gut flora:
- Antibiotics (these may be life-saving, but also kill the good bacteria, so long-term use is not advised).
- Tap water (this is only problem in areas with high fluoride and chlorine content in the water supply).
- Processed grains (not all grains harm gut health, but heavily-processed gluten and lectin rich grains certainly do).
- Environmental toxins (pesticides, fungicides, herbicides, insecticides, and of course the stuff like BPA, phthlates, and parabens).
- Chronic stress (results in elevated serum cortisol, which leads to increased permeability of the gut lining and damaged flora).