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Are Probiotics Safe for Your Immune System?

Although their benefits may be limited, probiotic supplements are generally safe for healthy people. But there are some situations where beneficial bacteria (either from foods or supplements) can post a threat to the host.

By
Monica Reinagel, MS, LD/N, CNS,
Episode #537
probiotics

Noreen emailed to ask “Could you do a podcast on probiotic foods that one should avoid if one has a compromised immune system? Is commercial yogurt ok since it’s pasteurized? What about kombucha? Homemade sauerkraut, pickles, hot sauces?”

Before I answer Noreen’s questions, let’s talk about how probiotic bacteria might affect the immune system.

One of the immune system’s jobs is to protect us from harmful bacterial. And the beneficial organisms that we refer to as probiotics contribute to this effort in a number of ways. In the gut, a robust population of beneficial bacteria can help crowd out harmful bacteria, making it harder for them to thrive. In addition, probiotic bacteria can influence the activity of our own immune cells, regulating inflammation, barrier function, and cell-to-cell signaling. 

How to Build a Healthy Microbiome

One way to foster healthy intestinal bacteria is to eat more of the foods these bugs like to eat—namely, fiber.  Increasing your intake of plant fibers from vegetables, fruits, legumes, whole grains, nuts, and seeds is like filling a bird-feeder with the kind of seeds that the beautiful songbirds you want attract like best. If you feed them, they will come!  

And if we want to attract a lot of different types of songbirds—er, bacteria—then we want to put out a variety of foods. That means you don’t just want to get all your fiber from a single source, such as a fiber supplement. You want to get it fiber from lots of different kinds of vegetables, fruits, legumes, grains, nuts and seeds. 

See also: How to Increase Fiber Without Overloading on Calories

Another way to nurture a healthy gut is to consume foods that contain beneficial bacteria. This includes things like yogurt, kefir, and other cultured dairy products; kim-chi, sauerkraut, and other fermented vegetables; miso, tempeh, natto, and other fermented soy products; and kombucha, which is a sort of fermented tea.   

It’s not clear how many beneficial bacteria survive their trip through the digestive tract and set up permanent housekeeping in the gut. But even if they are just passing through, they appear to be the ideal type of houseguest that leaves the place a bit better than they found it.

Now, to be honest, it’s not entirely clear how many of those bacteria actually survive their trip through the digestive tract and set up permanent housekeeping in the gut. But even if they are just passing through, they appear to be the ideal type of houseguest that leaves the place a bit better than they found it.

The Role of Probiotic Supplements

There’s a third way to introduce beneficial bacteria to the gut and that is through a probiotic supplement. But this is probably my least favorite way. Aside from persistent concerns about whether supplements contain what they are supposed to contain, and nothing that they are not supposed to contain, most supplements provide a relatively narrow selection of specific bacteria. 

Different strains of beneficial bacteria have very different effects in the body. One might tend to help prevent diarrhea. Another might help prevent constipation. Another might have benefits for the skin. Another might help reduce certain respiratory infections. And, frankly, some of them haven’t been shown to have specific benefits. 

But, if a certain strain of bacteria has been shown to have a certain positive effect, that’s the only benefit you can reasonably expect from it. So, if you’re after a certain benefit, you need to carefully match your supplement to the research. 

If, on the other hand, you’re just looking for overall gut health, I think you’re better off eating more prebiotic (fiber-rich) foods and enjoying a variety of cultured and fermented foods.

Is it Safe to Take Probiotics When You're Sick? 

Although their benefits may be limited, probiotic supplements are generally safe for healthy people. Occasionally, a probiotic supplement might produce side effects such as gas, diarrhea, or, in rare cases, skin itching or rashes. These generally are not serious and can be reversed by stopping the supplement.

But there are some situations where beneficial bacteria (either from foods or supplements) can post a threat to the host—that’s us. 

Acute illnesses such as pancreatitis, or a flare up of Crohn's, colitis, or celiac disease, can lead to increased intestinal permeability. As we’ve discussed in the podcast recently, this does not mean that bacteria or toxins leak out of the gut and into the bloodstream. But it may mean that bacteria (including probiotic bacteria) penetrate the lining of the gut far enough to kick up a big inflammatory reaction from the immune cells that are standing sentry there. If your gut is already inflamed, that’s the last thing you need.

There are some situations where beneficial bacteria (either from foods or supplements) can post a threat to the host—that’s us.

People with compromised immunity, either from a severe illness or due to medical treatment for a disease, are also frequently advised to avoid probiotic foods and supplements. Studies have found that using probiotics in severely ill or immunocompromised individuals can increase the risk of adverse effects such as infections.  

Can You Eat Yogurt if You Have a Compromised Immune System?

In her email, Noreen’s asked which foods you might need to avoid if you have a compromised immune system. In particular, she wondered whether commercial yogurt would be OK since it’s pasteurized.

Pasteurization, which kills all bacteria, would also kill beneficial bacteria. And that’s why the milk used in commercial yogurt is pasteurized BEFORE the bacteria are added to make the yogurt.  Commercial yogurt does contain live bacteria, as does kefir, kombucha, and any other probiotic food.

As to whether these are safe to eat, it's impossible to make a blanket statement about "people with compromised immune systems." A compromised immune system can encompass a wide range of situations. Whether yogurt is safe really would depend on the degree of immune suppression, and the nature of the illness or therapy. The NIH says that "The people who are most at risk of severe side effects include critically ill patients, those who have had surgery, very sick infants, and people with weakened immune systems." 

The situation with probiotic supplements (as opposed to foods) is even more complex. Patients receiving certain kinds of cancer therapies, for example, often suffer from diarrhea--and that’s one of the conditions that often responds well to specific probiotic supplements. However, researchers at MD Anderson Cancer Center in Houston recently reported that in a small group of patients receiving immunotherapy, a specific type of cancer treatment, those taking probiotic supplements were less likely to respond to the treatment. If you're receiving cancer treatment, be sure to discuss your use of probiotics (or any supplements) with your healthcare team.

Are Homemade Fermented Foods Safe?

Noreen also asked about homemade sauerkraut and other fermented foods. Indeed, there’s been a veritable explosion of home fermentation in recent years. (And given the fact that the yeast in some of these fermented foods gives off carbon-dioxide, there have been more than a few literal explosions, as well.) 

Home fermentation can be a fun way to introduce more probiotic foods into your diet. But whether you’re brewing your own kombucha, culturing your own yogurt, or fermenting your own pickles, it’s a lot harder to control exactly which bacteria you’re cultivating.

Whether you’re brewing your own kombucha, culturing your own yogurt, or fermenting your own pickles, it’s a lot harder to control exactly which bacteria you’re cultivating.

As a result, home-produced products are likely to contain a much wider variety of strains than a commercial product. Some of those will be beneficial, some may simply add flavor (either good or bad), but there is also a higher risk of incubating a pathogenic bacteria or two along with the good guys. 

In a healthy person, that might lead to an uncomfortable night in the john. But for someone with a compromised immune system, it could be much more dangerous. So, even if your doctor gives the OK to consume commercial yogurt, it might be best to steer clear of homemade produces if you're not in good health. Even if you're in excellent health, home fermenters are well-advised to be scrupulous about sanitation and safe food handling.  

GET MORE NUTRITION DIVA

Thanks to Noreen for her question. If you have a question that you think would make a good topic for a podcast episode, you can call the Nutrition Diva listener line and leave me a message. The number is 443-961-6206. I’d love to hear from you.  If you’d like to find out more about my nutrition coaching programs and groups, you can learn more at nutritionovereasy.com. To join the nutrition conversation, follow me on Facebook and Twitter. Listen and subscribe on Apple, Spotify, Google, Stitcher, or wherever you get your podcasts.

 

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