By: Erin Kukura, MS, RD
UCSD Recreation Dietitian
Probiotics have been a hot topic for the last few years and have been marketed as beneficial for improving gut health, skin and even mood but are any of these claims true?
What’s so great about the gut?
The gut microbiome is individualized to each person and contains a plethora of microorganisms. We are talking trillions of microbes including a variety of bacteria, with the majority of them residing in the large intestine. These bacteria are necessary for a variety of things including proper immune function and synthesizing Vit B12 and Vit K. Current research is just starting to understand how much our gut microbiome has an impact on chronic disease, mood, and immune system.
Given how powerful the gut microbiome is, research is looking at how we can enhance and replenish it especially when certain conditions have been shown to alter it. This is where probiotics and fermented foods have gained a lot of attention for their possible roles in providing more beneficial bacteria and re-establishing a healthy microbiome. Let’s delve into these a bit further.
The bacteria that resides in our gut feeds on fibers, which we cannot digest, these are known as prebiotics. In particular, asparagus, oats, garlic, chicory, onion, tomato, peas, wheat, banana and barley are excellent sources of prebiotics, among many others. This is why a high-fiber diet is so important and incorporating whole grains, legumes, fruits, and vegetables are so essential to maintaining a healthy gut and keeping the good bacteria alive.
Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” (1). The most common sources of probiotics are in supplement form (pill or capsule) or added to foods. Now, it’s important to know that just grabbing any probiotic off the shelf isn’t necessarily going to have the intended effect you may be looking for. Current research for probiotic benefits are strain-specific. This means only a particular strain or set of strains may be helpful for specific conditions.
Current research has found some strain-specific probiotics to be helpful for antibiotic-associated diarrhea, constipation and relief of some IBS symptoms but more research is needed until generalized recommendations can be made (2). Additionally, current research remains inconclusive in regards to probiotics and their effects on eczema and other health conditions.
It’s also important to note that probiotics are deemed a supplement and regulated as such and therefore not regulated to the same standards as medication. Therefore, quality, efficacy and accuracy of products can be uncertain.
Also, given the live, active cultures probiotics contain, the safety of probiotic use in individuals who are immunocompromised remains unknown.
What about fermented foods?
Kombucha, kefir, sauerkraut and other fermented foods have also had a renewed popularity in recent years with their proposed benefits on gut health.
Current research remains inconclusive with their effects as a probiotic. Additionally, these don’t necessarily fit the “true definition” of a probiotic as there are usually numerous strains with high variability in fermented foods due to the nature of food preparation. However, it appears some of the bacteria in these items do reach the gut, but it’s unclear how much of an effect they have on conferring microbiome changes.
However, we do know consuming fermented foods can be beneficial due to their activation of certain compounds (ie flavonoids) that have health conferring benefits and they also contain prebiotics and vitamins (3). Therefore, regular consumption of these products is likely beneficial for overall gut health.
A healthy gut microbiome is important for our overall health and we are just starting to uncover the links between microbiome and mood, inflammation, and other chronic diseases. Although probiotics have been touted as beneficial, there remains many questions surrounding efficacy. Therefore, it is important to work with your physician or dietitian to determine which strain(s) are indicated for a specific condition.
Likewise, incorporating everyday healthful habits such as eating plenty of whole grains, fruits, vegetables, getting adequate sleep, and managing stress all play a part in overall health and health of the gut microbiome.
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- “Probiotics.” International Scientific Association for Probiotics and Prebiotics. Accessed June 3, 2020. https://isappscience.org/for-clinicians/resources/probiotics/#toggle-id-1
- Wilkins, T. Sequoia, J. et al. Probiotics for Gastrointestinal Conditions: A Summary of the Evidence. Am Fam Physician. 2017; 96(3): 170-178.
- Dimidi, E. Cox, S. Rossi, M. Whelan, K. Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease. Nutrients. 2019; 11(8): 1806.