Probiotics are live microorganisms (tiny living things), mainly bacteria and sometimes yeast, and are intended to have health benefits when ingested. They are similar to the helpful microorganisms naturally found in the gut. Probiotics are found in supplements and fermented foods, such as Greek yogurt with added Lactobacillus and Bifidobacterium, kombucha, tempeh, kefir, and sauerkraut.
Do not confuse these with prebiotics, which are the food source for the “good” bacteria in our GI tract. Prebiotics are “a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon the host’s well-being and health.” They are carbohydrate compounds, primarily oligosaccharides, that withstand digestion in the GI tract and reach the colon where they then are fermented by the gut microflora, helping the good bacteria to grow. In short, they fall under the categories of soluble fiber and fermentable fiber. This is important, because even if you are taking a probiotic or eating foods rich in probiotics, you may not be receiving the maximum amount of benefits if you are not eating enough prebiotics (soluble and fermentable fiber). Foods rich in prebiotics include green bananas, onion, garlic, asparagus, artichokes, and leeks.
The human GI tract is colonized by many microorganisms, such as bacteria, viruses, fungi, archaea, and protozoa. The totality of these organisms is known as the gut microbiota, microbiome, or intestinal microflora and can affect the health and disease state of a human. Probiotics typically work in the GI tract to alter the intestinal microflora, adding good bacteria to the microbiome. The mechanism of action depends heavily on the species and strains because different species and strains have different effects. Some of the known mechanisms include the following:
The gut microbiota is the center of much current research. Researchers are suggesting that an imbalance in the gut microbiota could lead to several health issues including immune dysfunction, infection, obesity, and GI problems. The imbalance can come from medical conditions, stress, and antibiotic usage (which destroys bad and good bacteria).
Using a probiotic to restore balance has been shown to alleviate symptom persistence in irritable bowel syndrome (IBS) by 21% using both single-strain and multiple-strain supplements, with the mixtures being most effective. Studies also found symptom relief in ulcerative colitis, reduction in acute diarrhea duration and frequency, and lower risk of diarrhea from antibiotic use by 51% or clostridium difficile infection.
A healthy gut with plenty of good bacteria has also been shown to improve the immune system, combat inflammation, and potentially reduce bad cholesterol (total and LDL cholesterol).
Remember, not all probiotic strains and species are created equal. Trying to figure out exactly what strain, species, and genus of probiotic will work for you and your needs can be tedious, because there are thousands upon thousands of variations. It may take some trial and error to finally find a probiotic that meets your needs.
The good news is that both Lactobacillus and Bifidobacterium are the most studied probiotic genera. There are several studies of strains from these two genera that have produced positive results. Below is a list of conditions with the genus and strain of probiotic that has shown promise in helping with the condition.
If you are struggling with GI symptoms and considering a probiotic supplement, it is important to talk this over with your Registered Dietitian (RD) and primary care provider. They can help to identify the correct genus, strain, species, and dose you need.
For those healthy individuals, you most likely do not need a probiotic supplement. If you really want to help your gut, follow these tips:
As always, reach out to the NIFS Registered Dietitian for nutrition help, including nutrition management of gut-related issues. We are here for you.
This blog was written by Sabrina Goshen, NIFS Registered Dietitian. To learn more about the NIFS bloggers, click here.