A healthy serving of yogurt that contains plenty of probiotics.

What are probiotics, and how do they help digestive health?


December 13, 2019

A nurse practitioner explains probiotics, “gut flora” and things to consider about yogurt.

We see the word “probiotic” on food labels, especially relating to yogurt. At Vanderbilt Walk-in Clinics, nurse practitioner Robert Anderson, DNP, APRN, cares for people dealing with ailments that often affect the digestive system. He also sees how often antibiotics are prescribed for various illnesses. Here, Anderson answers questions about probiotics, diet and how antibiotics can create problems.

Question: What does the term “probiotic” mean?
Answer: “Probiotic” means live bacteria and yeast that’s actually good for you. “Probiotic” literally means “for life.”

Question: Are probiotics mainly good for the digestive system, or in other ways, too?
Answer: The focus now is on digestive health. Good bacteria keep bad bacteria in check in the gut. There’s a thing with bacteria called colonization resistance. A healthy colony of good bacteria in the gut helps suppress bad bacteria.

Question: The idea of bacteria living in our digestive tract is pretty unappetizing, but science is learning that the gut “biome” is natural and that it influences our health. How does the gut get full of bacteria?
Answer: When you’re born, your gut is sterile. You get your initial burst of probiotics through the birth process. You get it through breastfeeding. But after that, it’s through digestion — when exposed to what your family has. Gut flora (the type of organisms living in the digestive tract) tends to be similar in families (because everyone in the family tends to eat the same foods). So that’s how our gut tends to get populated – for better or for worse. Certain organisms digest certain things. Your gut flora will change with changes in your diet. Your gut bacteria can change if you move from one country to another.

Question: What’s the connection between probiotics and yogurt? Does all yogurt contain probiotics?
Answer: Milk is turned into yogurt by lactobacilli bacteria; that’s how it becomes yogurt. But depending on how a certain yogurt is processed, the pasteurization process may have killed the active cultures. So if you’re eating yogurt to get probiotics, be sure the label says “active cultures.” You’re going to find active cultures in yogurts, kombucha, kefir. And sauerkraut, fermented foods such as that. It’s a good way of getting active organisms into the system.

Question: Does the fat content of yogurt affect how many live cultures are in it – nonfat yogurt vs. full fat, for example?
Answer: It shouldn’t affect the culture.

Question: How can someone tell if their gut biome – the mix of organisms in their digestive tract – is healthy or unhealthy?
Answer: There’s no way to tell without growing a sample in a lab culture. There are thousands of bacteria in our gut, so there’s no way of knowing. Of course, if you were taking antibiotics and within the next two months you’ve developed diarrhea, that might be due to an alteration in your gut flora. But there’s no way of actually knowing. Obviously, a symptom, like diarrhea – that means there’s a problem somewhere. It could be viral, it could be bacterial, it could be so many different things. The answer isn’t always a probiotic.

Question: There are probiotic supplements that you can take, like vitamins. How do you know if you should take probiotic supplements, and which kind?
Answer: The supplements are very species- and strain-specific. The two or three most studied ones are lactobacillus, the bifidobacteria, and Saccharomyces boulardii, which is a yeast. Some are good for antibiotic-related diarrhea. Some are good for constipation issues; they promote regularity.

Talk to your primary care provider or a gastroenterologist. If you’re going to research this by Googling, consider the credibility of the information you’re finding. A good source of information is the National Center for Complementary and Integrative Health, which is part of the National Institutes of Health.

Question: How are probiotic supplements dosed?
Answer: There are different strengths, for different reasons to take them. You’re looking at how many colony-forming units are in them. These are not regulated by the FDA. They’re a supplement. There are no regulations concerning how they’re labeled. You have to buy them with caution; you need a reputable supplier.

Question: What brands or retailers can you trust?
Answer: Culturelle, Align, Floraster are well-known brands. There are other reputable brands out there.

Question: Yogurt is widely considered a healthy food for children. What about supplements for children?
Answer: The best thing to do is to introduce children to the yogurt, kombucha, kefir, sauerkraut, pickled foods and fermented foods. Diet is always better than supplements for anything, whether it’s a vitamin or a probiotic.

Address the sugar. You have to look at the sugars for kids. The majority of yogurts have a huge sugar load. Gummie vitamins do, too.

I think it is safe to give children a probiotic supplement, especially with our germ fixation. We’re hand-washing, we’re hand-gelling, we’re sanitizing everything.

Question: So we’re killing too many good bacteria?
Answer: Yes.

Question: Explain antibiotic-associated diarrhea, and how some health care providers advise patients to take probiotics to guard against that?
Answer: Antibiotic literally means “against life.” Antibiotics kill bacteria – good, bad or indifferent. So the danger is, this medicine inhibits the growth of good bacteria. So you can get an overgrowth of the bad bacteria, or a drug-resistant strain. Antibiotic-associated diarrhea can rear its ugly head for up to eight weeks after taking an antibiotic. Many people take probiotics to prevent that. Often, their doctor or nurse practitioner advises them to eat yogurt while they’re on the antibiotic. Ask about which kind of yogurt will help – often they contain the wrong type of probiotic species and too little colony-forming units to help.

Another important thing: You have to separate your probiotics from your antibiotics. If you take them at the same time, you’ll kill the probiotics. You have to separate them by two hours.

And you need to talk to your health-care provider about it. Typically it’s a higher dosing of those quality brands for the period of time you’re taking the antibiotic, plus at least another week. And if you wait for the diarrhea to start, it’s hard to catch up. The probiotic would not be of benefit at that point. You have to stay on it from the beginning.

Question: Are there reasons not to take probiotics?
Answer: Yes. Certain people should not: the critically ill, immunocompromised, the very old, the very young, or if you had recent surgery. If you think of the millions of people who take probiotics, I think overall they’re safe. But there are specific people who should probably avoid them. They are live organisms you’re introducing into the body.

Question: What does the term “pre-biotics” mean?
Answer: They are compounds that promote the growth and activity of beneficial organisms. A good analogy would be fertilizer. Typically these are the fiber-rich foods.

Question: Meaning, lots of fresh fruit and vegetables.
Answer: Onions, garlic – those are huge. Basically, all fibers are prebiotics. There’s pectin in the apples, inulin in the onions.

Question: Thus, if you’re trying to get plenty of probiotics, you also want to eat lots of fiber.
Answer: Yes. And if it’s processed anything, you probably should avoid it. If your great-grandmother couldn’t look at it and say, “that’s food,” you should avoid it.

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