Bugs For Sale: The role of probiotics, prebiotics & synbiotics in gut health

Our concern has been to avoid pathogenic bacteria, but emerging science tells us we also need to pay attention to cultivating enough healthy bacteria, too.

 Fresh bunches of carrots with stems.Who knew that in the 21st century we would become so preoccupied with bacteria? Long considered a lower life form, scientists today consider these microorganisms highly evolved, with elaborate systems for adaptability and resilience. Basically they deserve more respect.

Simpler life forms such as microbes adapt far more readily to changing conditions that we do, seamlessly sharing and transferring genes to accommodate their needs, often to the detriment of their host. With escalating rates of disease linked to inflammation, the role of bacteria and gut health demands our attention.

Working with Microbes

Our long standing concern has been to avoid pathogenic bacteria, but emerging science tells us we also need to pay attention to cultivating enough healthy bacteria, too. The marketplace has been quick to respond with a range of probiotic foods, beverages, and supplements claiming to offer live cultures that replenish our gut with healthy bacteria.

Prebiotics offer another approach, providing the right kind of food to nourish beneficial microbes. Synbiotic products provide both. These formulas are typically produced in highly controlled environments, but offer only a few selected strains of bacteria.

Do these products deliver? Enough to get our attention, but not always.

The World of Supplements

A 2013 review of the literature hints at the promise of treating the disease with probiotics. In addition, recent advances treating serious gut disease with fecal transplantation–basically introducing healthier bacteria from volunteer donors–adds additional intrigue. But delivering active cultures in supplement form remains a challenge.

In many cases probiotics need to be refrigerated to help preserve their limited shelf life, and even that may not be enough. A small study in 2004 measured the probiotic organisms in 20 brands of supplements. None of the products provided the amount advertised on their label. In addition, eight of the samples provided only 10% of what they claimed, and two samples supplied no viable probiotics at all.

Proponents of supplements counter that sometimes probiotics offer benefits even when the culture is not viable or in a dormant state. The issue is far from settled. Currently The International Scientific Association for Probiotics and Prebiotics (ISAPP) offers consumer recommendations for choosing supplements. Unfortunately, many consumers find them expensive and out of reach.

Food First

While supplements possess the potential to help improve gut health, they can’t completely replace the impact of a microbe friendly diet. What we eat determines up to 60% of the mix of microbes that reside in our gut.2 Eating enough whole foods–both cooked and raw– with a healthy dose of fermented foods may do the trick.

Scientists call most of their efforts preliminary when it comes to understanding the microbiome. Since supplements are expensive and not always reliable, I find myself looking to food first.

What has been your experience?


  1. Sandor Katz. The Art of Fermentation. Chelsea Green Publishing, 2012.
  2. van Hylckama Vlieg et al. Impact of microbial transformation of food on health-from fermented foods to fermentation in the gastro-intestinal tract. Curr Opin Biotechnol. 2011;22(2):211-9.
Published on: March 11, 2015
About the Author
Photo of Bonnie Modugno MS RD

Bonnie is a registered dietitian in private practice specializing in energy metabolism, sport nutrition, maternal, infant and child nutrition. You can find more from Bonnie on her blog muchmorethanfood.com and on Twitter as @MoreThanFoodInc.

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Recent Comments

I want to know more about probiotic dairy products such as Bio-Yoghurt, cheese and kefir.

I agree that what is most important in good wholesome food not supplements . Thank you for re enforcing my view.