A guide to understanding probiotics, prebiotics, and postbiotics

You probably know at least a little bit about probiotics and possibly even prebiotics if you’re aware that the health of your gut microbiota, the population of bacteria and other microorganisms that live in your large intestine, is crucial for your overall health. However, how about postbiotics? There are several “biotics” out there, but sadly, a lot of the information that is available about them is not entirely factual. Let’s make a few corrections.

Probiotics

According to a nonprofit scientific organization called the International Scientific Association for Probiotics and Prebiotics, probiotics are “live bacteria that, when provided in sufficient proportions, confer a health benefit”. You can find probiotics in the following places:

• Nutritional supplements
• Some (but not all) fermented foods, such as yogurt and kefir, include bacteria
• A few non-fermented dishes

Probiotics must be good for your health and contain specific bacteria that are alive in enough numbers to help your health when you eat them, no matter what form they come in.

Bifidobacteria and Lactobacilli are the two most popular probiotic species. Yogurt and other fermented dairy products, like kefir, are made by adding these bacteria to milk. They occasionally appear in fermented nondairy foods such as tempeh, miso, kimchi, kombucha, and sauerkraut. Remember that while numerous fermented foods are healthy and beneficial in other ways, they no longer have any active probiotic microbes. For this reason, when purchasing yogurt, for instance, look for the logo that reads “live and active cultures”. If the label only states, “made with active cultures”, the probiotic microorganisms might have been destroyed during heat processing.

Prebiotics

Prebiotics are substances, according to ISAPP, “that are selectively consumed by host microorganisms, giving a health advantage”. In other words, prebiotics provides food for the good bacteria and other microorganisms that have already been living in your gut microbiome for so long. Prebiotics are carbohydrates in the food that your body can’t break down. They pass through your stomach and small intestine without being broken down, but when they reach your large intestine or colon, healthy bacteria eat them or ferment them.

One form of prebiotic, resistant starch, is present in foods including beans, underripe bananas, whole grains, cold-cooked potatoes, and pasta. Another is fructans, which are present in a variety of plant-based foods like rye, barley, wheat, leeks, onions, garlic, and raisins, as well as in asparagus, artichokes, bananas, and raisins. Although fructans are healthy for you and your gut, some IBS sufferers experience digestive irritation after consuming them.

For those who are curious, a synbiotic is a combination of probiotics and prebiotics. But now, let’s talk about postbiotics.

Postbiotics

The first page of online search results for ‘postbiotics’ contains many false claims, some of which come from ‘experts’. Postbiotics are sometimes described as “byproducts of the fermentation process carried out by probiotics in the intestine” or “the waste products left over after your body digests both prebiotics and postbiotics”. Postbiotics may be claimed to be present in fermented meals, or you may see headlines like “The secret to obtaining the advantage of postbiotics from foods”. Let’s clear up all of this misinformation.

According to ISAPP, postbiotics are “A preparation of inanimate microbes and/or their components that gives a health benefit”. Postbiotics can comprise fully inactivated bacteria as well as microbes in various stages of inactivation. ‘Inactivated’ just means that they are lifeless or nonviable, not necessarily dead. They remain bioactive or still retain the capacity to impact us or other living things.

The “waste left behind”, also known as byproducts of prebiotic fiber fermentation by probiotic microorganisms in the intestines, does not fall under this definition. A postbiotic can be made from a variety of bacteria, not just those that fit the probiotic criteria; it’s not the byproducts that are important in this case.

How true is it that postbiotics are present in fermented foods? Even though some fermented foods, particularly those that are baked or pasteurized, could include microbes that are nonviable when humans eat them, this does not fulfill the criteria of a postbiotic. A key component of the definition of a postbiotic is that it must be produced in a controlled, repeatable manner to ensure uniformity between batches and to enable the product to be examined in research studies to determine whether it provides a health benefit.

Since different postbiotic treatments include various combinations of microbes or their parts, they may have a variety of physiological consequences. The immune system, metabolism, enteric (gut) and central nervous systems, as well as the gut microbiota, are all potential targets for negative health impacts. Clinical trial data on humans, however, is scarce and of varying quality.

Postbiotic products are being promoted by several dietary supplement businesses with the promise of better immune function, weight loss, and digestive health. Some pills even combine prebiotics, probiotics, and postbiotics. Are these statements credible? Do you need to take them? On both counts, the data at hand indicates probably not.

Any health advantages associated with probiotics and postbiotics are particular to each preparation or product. Generalized health claims cannot be justified in any way. However, many postbiotic supplement producers continue to target consumers who are currently in good health and are looking to ‘optimize’ wellness. Any product that is worthwhile to buy will have been shown to have health advantages in human clinical trials, and the manufacturer should be able to produce proof of those benefits. This is true whether you want to try a ‘biotic’ supplement or modified food. If the feature suits your requirements, you might think about purchasing it. And sure, the burden of what I just mentioned falls on you, the consumer. Unjust, but fair.

The ISAAP has a ‘for consumers’ page (isappscience.org/for-consumers) where you may find more dependable, trustworthy information on all of the ‘biotics’ as well as fermented foods. Visit usprobioticguide.com for a guide to probiotics that are available in the US, what they can assist with, and how reliable the data is to back up those recommendations.