We’re never too old to learn. That’s why I appreciated the kind letter from Professor Emeritus Bob Hutkins from the Department of Food Science and Technology at the University of Nebraska.

“Thank you for your informative columns that I read regularly in the Lincoln Journal Star. The probiotics quiz was spot on except for the question about food sources. While I would certainly agree that the microbes in fermented foods may provide health benefits, my view and that of other scientists in the field is that they (the foods themselves) cannot technically be called probiotics.

"To qualify as a probiotic the microbe (good bacteria) must be characterized to the strain (subtype) level, be alive at an effective dose and show benefits in randomized controlled trials. While yogurt and kefir usually do contain strains that satisfy the probiotic criteria, many other fermented foods like sauerkraut and kimchi contain naturally occurring microbial communities that will vary from batch to batch. Same for most cheeses.

"Also, vinegar rarely contains any live bacteria, nor does sourdough bread.

"Barbara, please forgive me for pointing out these corrections. I really do enjoy and learn from your column.”

No apologies needed. In fact, I was thrilled to learn that you are a member of prestigious International Scientific Association for Probiotics and Prebiotics (ISAPP). And that the second edition of your book, "Microbiology and Technology of Fermented Foods," has recently been published.

Thanks for writing and thanks also for addressing some follow up questions I had after taking a look at the ISAPP website (isappscience.org). These experts suggest we look for probiotics that have been “validated” — proven with good scientific studies to have a health benefit.

“That’s why, for most yogurts and kefirs, manufacturers list the names of the microbes on the label,” Hutkins explained. “Many of those strains (such as bifidobacterium, lactobacillus and lacticaseibacillus) have been shown to meet the strict definition of probiotics in clinical trials.”

Remember, too, that these good bugs need to be alive when we ingest them. Products such as yogurt, kefir and most cheeses do retain live microbes. Not all fermented foods can be classified as “probiotics” however, says Hutkins.

Good bacteria in foods that are heated or undergo several processing steps do not survive. Sourdough bread and wine fit into that category; they are fermented foods but not technically “probiotics.”

Sauerkraut may or may not be heat-treated. And according to Hutkins: “It’s simply not possible to identify the (various types of) microbes in each batch, much less isolate them and conduct a clinical trial to validate it’s health benefits."

Why all this technicality about probiotic foods? Researchers are finding lots of good evidence that consuming fermented foods with live microbes may lead to a wide range of positive health outcomes, says Hutkins. That’s worth trying to understand.

©2025 MediaNews Group, Inc. Distributed by Tribune Content Agency, LLC.