Probiotics are live bacteria and yeasts considered to have beneficial effects. 

Prebiotics, Probiotics, and Postbiotics

The human colon may represent the most biodense ecosystem in the world. Though many may believe that our stool is primarily made up of undigested food, about 75 percent is pure bacteria—trillions and trillions, in fact, about half a trillion bacteria per teaspoon. As Neil deGrasse Tyson put it, “More bacteria live and work in one linear centimeter of your lower colon than all the humans who have ever lived.”

Do we get anything from these trillions of tenants taking up residence in our colon, or are they just squatting? They pay rent by boosting our immune system, making vitamins for us, improving our digestion, and balancing our hormones. We house and feed them, and they maintain and protect their house, our body. Prebiotics are what feed good bacteria. Probiotics are the good bacteria themselves, and common ones are Bifidobacteria and Lactobacillus. And postbiotics are what our bacteria make.

How Probiotics May Benefit Us

One month of probiotics has been found to significantly decrease symptoms of anxiety, depression, anger, and hostility, and a variety of mechanisms has been proposed for how our intestinal bacteria may be communicating with our brain. Taking probiotics may also result in us having significantly fewer colds, fewer sick days, and fewer symptoms.

Good Sources of Probiotics

Commercial yogurt of any kind—whether soy, rice, cow, or coconut—is an insufficient source of the level of probiotic bacteria found effective in treating diarrheal illnesses, inflammatory bowel disease, and irritable bowel syndrome. However, a plant-based diet appears to naturally modulate our gut flora.

When Should We Take Probiotics?

Does it matter if we take probiotics before, during, or after a meal? Though foods may be better carriers for probiotics than supplements, if one does choose to go with supplements, they are most effective taken within 30 minutes before, or simultaneously with a meal or beverage that contains some fat content.

Side Effects of Probiotic Supplements

Researchers gave half of their study participants, people with pancreatitis, probiotics and the other half got sugar pills. Within ten days, the mortality rates shot up in the probiotics group, compared to placebo. More than twice as many people died on the probiotics. So, taking probiotics for acute pancreatitis is probably not a good idea, but, further, taking probiotics in general can no longer be considered to be completely harmless.

Favor Eating Prebiotics Over Popping Probiotic Supplements

There are myriad concerns with probiotic supplements, and they may not even be alive by the time you buy them. They also have to survive the journey down to the large intestine. Altogether, these points suggest that the advantages of prebiotics—found in plant foods—outweigh those of probiotics.

Taking Probiotics with Antibiotics May Make Things Worse

The irony is that probiotics can actually interfere with microbiome recovery after antibiotics, rather than facilitate it. Probiotics are often intentionally selected to be antibiotic-resistant so they can be co-administered with antibiotics to reduce diarrhea rates, but they may transfer that resistance to pathogens in the gut. They can also have opposite the intended effect. Without probiotics, spontaneous post-antibiotic recovery back to baseline was found to occur within three weeks. In contrast, the microbiomes of those randomized to take probiotics remained off-kilter even six months later.

The information on this page has been compiled from Dr. Greger’s research. Sources for each video listed can be found by going to the video’s page and clicking on the Sources Cited tab. References may also be found at the back of his books.

Image Credit: AnnaMariaThor / Thinkstock. This image has been modified.

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