5 Facts about Probiotics… to Help You Filter through the Myths


The other day I got a message from my sister saying that she had read something about how to determine a good probiotic. The post or article or whatever it was sounded logical, but some how didn’t seem exactly accurate to her, and she wanted my feedback on what she had read. I had a look and she was right… it sounded logical and there were major flaws in the information. I’m really glad she contacted me, as I love every opportunity I get to clear up nutrition-related myths!

And it got me thinking that there are probably others who have read similar (or maybe even the exact same!) information and that you wouldn’t recognize it as wrong, if you don’t really understand probiotics and what they do for us. So, let’s put some real facts about probiotics on the table so you can know if the probiotic you are choosing is a good one.

Fact #1: Most of the time, you want multiple strains of bacteria in your probiotic… but not always.

Probiotic is a fancy name for good bacteria and yeast that live in your digestive system and do good things for you. Of bacteria alone, research has found more than 1,000 different species living in human guts. You can see in this table the eight main phyla and the class, family and genus (where that information will be applicable based to something later in this article).

Gut BacteriaEven though there are 1,000 species that have been found, each person tends to have only 150 to 170 species that are present in enough of a quantity to make a difference. Despite it being a small-ish number compared to the possibilities, this mix is important as the different types of bacteria and yeast do different things for us. For example:

  • Lactobacillus rhamnosus GG has been shown to reduce the risk of traveler’s diarrhea.
  • Bifidobacterium lactis Bb12 was found to improve the frequency and ease of bowel movements in the elderly.
  • The yeast Saccharomyces cerevisiae variety boulardii can help increase the small intestine’s production of digestive enzymes and improve a leaky gut.

Usually, I recommend that people look for a probiotic that has at least 5 different strains for general health. However, this recommendation can change depending on why the person is taking the probiotic. In specific situations, I may recommend a single strain probiotic or a specific multi-strain probiotic that includes the specific strain we want.

(By the way, the yellow outline on some of the boxes above indicate the types of bacteria that are most commonly found in probiotic supplements. As you can see, it’s not everything that’s living inside of us!)

Fact #2: Probiotics can survive in your body, even if they need to be refrigerated.

Probiotics are living things. They need food to survive. They need to have their waste taken away from them. They also tend to hibernate when they are cold. The reason some probiotics need to be refrigerated is so the microorganisms don’t die from starvation or rotting in their own waste, until they can be freed from the tiny capsule in which they patiently wait for you. Once the bacteria are in your gut (at a balmy temp of 98.6°-ish), they can ramp up their metabolic processes because you will feed them and take their waste away.

The more bacteria in a capsule (known as CFUs, or colony forming units), the more likely it is that it needs to be refrigerated. And this makes total sense! Imagine if Manhattan was enclosed in a capsule. We would run out of food and generate waste far more quickly, than if the same size capsule enclosed a portion of, say, Nebraska.

Also, be aware that if a probiotic needs to be refrigerated, it doesn’t mean that all of the bacteria will die in one day from being in a warmer environment. Most reputable probiotic brands will produce a viability chart that shows how many of the CFUs continue to survive at different temperatures over time. Here is an example from Klaire Labs Ther-Biotic Complete (one of the probiotics that I recommend):

Klaire Labs Therbiotic CompleteAs you can see, even if you kept this product on the counter in North Carolina for a month (assuming that’s about 86°F), most of the bacteria would still be alive when you swallowed the capsule.

(If you are considering a probiotic supplement that has a large number of CFUs, like 10+ billion, and it doesn’t need to be refrigerated, I suggest contacting the manufacturer for viability information just to be sure you know what you’re getting based on the manufacture date.)

Fact #3: Lack of milk curdling does not mean a probiotic is inactive.

Take a quick look at the different types of probiotics above and recall that I said each of them does something different for us. One of the reasons they provide different benefits is because they eat different foods and give off different substances as a result. If your probiotic supplement curdles milk, all that means is that your probiotic contains a species that consumes one of the nutrients in milk (usually lactose). That’s all. If your probiotic doesn’t curdle milk, it is possible that all of the bacteria are dead… or that they prefer to dine on something else (you know, bacteria can be lactose intolerant too! Ha!).

The other thing to note about this is many bacteria that can feed on milk also can eat other things and this is good! For people who are not lactose intolerant, we digest lactose in the small intestine and the resulting monosaccharides are absorbed into the body. When this occurs, the bacteria that live in the large intestine never see the lactose and, therefore, don’t need it to survive. Here are some examples of bacteria that live in the colon (so don’t rely on milk for food) and the benefit they give to us.

  • Bacillus subtilis produce vitamin K2, which is necessary for bone health (as opposed to blood clotting which is what K1 is for).
  • Bifidobacterium longum (along with several other Bifidobacterium species) consume fiber and produce short-chain fatty acids which are the energy source for colon cells.
  • Enterococcus faecalis, Bacteroides fragilisStaphylococcus epidermidis and other bacteria can metabolize gliadin-peptides from gluten (which may explain why humans could handle gluten before most of our wheat became treated with pesticides and our microbiome lost its diversity)  and also give us short-chain fatty acids.

Because different species provide different assistance, I recommend probiotic supplements with multiple strains, as well as eating probiotic foods such as kimchi, kefir, kombucha, natto, kvass, sauerkraut, pickles, raw cheese and yogurt.

As a side note, I read in Anthony William’s book The Medical Medium that raw, organic fruits and vegetables have good bugs living on them that contribute to our microbiota. I haven’t been able to find any research to confirm this, but can’t refute what he wrote since he says Spirit is his source… and it makes sense to me. Depending on your need for scientific research to back your beliefs, you can decide how you feel about this possibility.

Fact #4: Good bugs devour and help us fight bad bags, among other things.

Good gut bugs have been shown to keep bad gut bugs in check, by not letting them establish large colonies which can lead to illness. (This is why a stool analysis or endoscopy may show “bad” microorganisms are present, but the person doesn’t have any symptoms associated with them.) They may do this by consuming the food that the bad bugs would eat or maybe they kill them directly. I don’t know, but it works!

As well, beneficial microbes help educate our immune system so our immune cells know when a bad bug is present and needs to be removed. By informing the immune system, a balanced microbiome reduces the risk of autoimmune diseases, “seasonal” allergies, hives, yeast infections and urinary tract infections. This is one of the reasons that I recommend people double up on their probiotic intake the minute they feel a cold or other microbe-related illness coming on.

Finally, having the right number and variety of good bugs (and limited numbers of bad bugs) helps to maintain integrity of the intestinal wall (i.e, prevent leaky gut), keeps us pooping at the right rate and consistency, and tells our body to burn energy rather than store it as fat. A healthy microbiota has also been linked to healthy skin, lungs, brain (through the gut-brain axis) and reproductive system. Research hasn’t figure out all the mechanisms yet, but they will. In the meantime, I’m sure we will hear more and more about how our microbiome is contributing to or taking away from our overall health and well-being.

Fact #5: We’re not sure if we need to take a probiotic every day.

Despite all the benefits of probiotics, it’s not clear if we need to take a probiotic supplement every day. I know, I hate not having a cut and dried answer, but this is how it is right now!

In my research, I have found two sides of this discussion, both of which include reputable healthcare practitioners. One side says that we need to take a probiotic every day because we don’t get enough probiotics in our daily life through fermented foods, interaction with dirt, etc. They also say that many of us don’t get enough fiber to keep the bugs fed and the the strains in probiotic supplements only last in the gut for a short period of time (less than two weeks). It’s worth noting there are plenty of case studies of people whose symptoms went away and the only change they made was taking a probiotic every day.

The other side of this discussion says that we need them sometimes (like after taking an antibiotic), but not every day. Their premise is that, even though the microbes from the supplement may only hang out for a short time, their presence helps other strains take up residence in the intestine. They do say that maintaining a healthy microbiome is only possible when we eat probiotic containing foods and plenty of fiber on a daily basis, emphasizing the additional extra-intestinal benefits that come from a whole food based diet. Plus, there is some evidence that taking a probiotic if you have some sort of bacterial overgrowth can make the situation worse.

Honestly, I don’t have a position yet. Taking them every day won’t hurt you (unless you have a reaction to one of the strains). At the same time, a good probiotic can be expensive and I’m not comfortable telling someone that they have to take an expensive supplement every day, unless I have evaluated the person and have a specific reason why. Therefore, as with all supplements, talk to your healthcare provider about whether or not a probiotic supplement is a good choice for you… and if it is, which one will give you what you’re looking for. Then, no matter if you decide to take a probiotic supplement or not, eat more probiotic-containing foods and consume plenty of fiber from vegetables, fruits and legumes.


— American Gut. Preliminary Characterization of the American Gut Population. Accessed on February 3, 2016.
— Buts JP, Bernasconi P, Van Craynest MP, et al. Response of human and rat small intestinal mucosa to oral administration of Saccharomyces boulardii. Pediatr Res. 1986;20:192-196.
— Caminero A, Herrán AR, Nistal E, et al. Diversity of the cultivable human gut microbiome involved in gluten metabolism: isolation of microorganisms with potential interest for coeliac disease. FEMS Microbiology Ecology. 2014;88(2):309-19.
— Garcia Vilela E, De Lourdes De Abreu Ferrari M, Oswaldo Da Gama Torres H, et al. Influence of Saccharomyces boulardii on the intestinal permeability of patients with Crohn’s disease in remission. Scandinavian journal of gastroenterology. 2008;43(7):842-8.
— Gut Microbiota for Health. Gut microbiota info. In About Gut Microbiota. Accessed on February 3, 2016. http://www.gutmicrobiotaforhealth.com/en/about-gut-microbiota-info/
— Hilton E, Kolakowski P, Singer C, Smith M. Efficacy of Lactobacillus GG as a diarrheal preventive in travelers. J Travel Med. 1997;4:41–43.
— Hiratsuka T, Furihata> K, Ishikawa J, et al. An alternative menaquinone biosynthetic pathway operating in microorganisms. Science. 2008; 321(5896):1670-1673.
— Kovacs B. Probiotics. In Health and Living. September 10, 2015. Accessed on February 3, 2016.
— Pitkälä KH, Strandberg TE, Finne-Soveri UH, et al. Fermented cereal with specific bifidobacteria normalizes bowel movements in elderly nursing home residents, a randomized, controlled trial. J Nutr Health Aging. 2007;11:305–311.
— Scott KP, Martin JC, Duncan SH, et al. Prebiotic stimulation of human colonic butyrate-producing bacteria and bifidobacteria, in vitroFEMS Microbiology Ecology. 2014;87(1):30-40.

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  • The colon, in particular, is home to a huge number of toxins that accumulate over time. Most people are utterly unaware of this problem and do not realize steps have to be taken to address their presence or else they will not go away.

    Perfect Biotics serves as a means of addressing the issue of toxins and, in turn, also addressing ways to improve how the digestive system functions.

    • Thanks for the suggestion on the probiotic, Margo. I’d love to see the stability studies for this probiotic as I couldn’t find them on-line? Just want to be sure people are getting those 30 billion cells when they keep the bottle at home on the shelf (since it says they don’t need to be refrigerated).

  • 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.

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