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Fermented Foods and Probiotics by Erica Sonnenburg

This weekend I followed up with Erica Sonnenburg, PhD, senior research scientist at Stanford University School of Medicine in the Department of Microbiology and Immunology, (also author of The Good Gut). Erica presented at a salon, Understanding the Microbiome in April 2017, which is available on our Youtube channel. I was curious to learn more about fermented foods and probiotics.

Please describe the difference in benefits we receive between fermented foods and probiotics.

Fermented foods provide living bacteria (assuming the food has been stored properly and the microbes haven’t been killed, ie not pasteurized). Fermented foods also supply the fermentation products of those microbes, ie the chemicals that the microbes make as part of their growth in the fermented food. It is possible that some of these chemicals may have beneficial properties, which would not be found in a probiotic supplement since that only includes bacteria. In addition, bacteria in fermented foods also lowers the glycemic index of that food making it less sugary than in the absence of fermentation. You can tell when you eat unsweetened yogurt that it is less sweet than drinking milk.

Do you feel that probiotics are helpful? It sounds like this is variable based on the individual?

Because the safety profile on probiotics is so high, I think there is not much harm in trying them out and if you find that they seem to help or make you feel better, then, why not use them? They are expensive and my guess is that they won't be as good for you as fermented foods would be, but until all the data is in, we don't know for sure.

Are probiotic supplements able to survive the acidic environment of the stomach?

We've actually tested this and it does seem like some make it through alive. But remember, even if all made it through alive it would still be a very small fraction of the total microbes already living in your gut. We house about 100 trillion microbes, many of these probiotic supplements advertise an amount of microbes in the billions range, which would only be about 0.1% of the total microbes assuming all the bacteria in the supplement is alive and makes it to the colon alive, so it's probably even way less than 0.1%. 

Should probiotic supplements be refrigerated?

For the most part yes since refrigeration will help keep the microbes alive for longer, but there are some probiotic bacteria that can form spores and they can be quite stable at room temperature. These spore forming probiotics are usually the ones you see in shelf stable products like energy bars, granola, or peanut butter.

Erica Sonnenburg, PhD

Erica Sonnenburg, PhD, is a senior research scientist at the Stanford University School of Medicine in the Department of Microbiology and Immunology where she studies the role of diet on the human

intestinal microbiota. She has published her ground breaking scientific findings related to the microbiota in prestigious journals such as The Proceedings of the National Academy of Sciences, Cell, and, Nature.

She is the co-author, along with Justin Sonnenburg, of the book The Good Gut: Taking Control of Your Weight, Your Mood, and Your Long-Term Health. 

Erica has two school-aged daughters. In her free time she enjoys gardening and cooking for her family and their trillions of microbes!

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