I recently found myself in a health food store handing over my credit card to buy over a hundred dollars worth of supplements and food products promising to boost the health of my gut microbiome. In my basket was kombucha (fermented tea), kimchi (fermented cabbage) and a jar of probiotics promising ‘a range of health benefits supporting overall health and wellbeing'.  

I had been reading about the amazing highly complex, highly diverse community of microorganisms that make the human body their habitat. The tiny critters living in our gut have been shown to play a key role helping us digest food and extract energy, they’re our first line of defence when it comes to disease and they can even influence our mood and behaviour. Last week I wrote about their link to obesity, inflammatory bowel disease, cancer, heart disease, multiple sclerosis and autism. So when I found myself in a store surrounded by products promising me the health benefits of ‘good bacteria’, I was a willing consumer.  

It wasn’t until I got home that I realized I might have just repeated the same mistake I’ve made many times over since being diagnosed with an autoimmune disease. In the last ten years I’ve spent more than $30,000 trying everything from prescription drugs, to elimination diets and alternative therapies. So I couldn’t help but wonder if I’d fallen for the hype all over again. When it comes to boosting health and wellbeing, is there any evidence probiotics work?  

The good news is there are hundreds of studies considering how we could use probiotics to treat illness. The bad news is that most of them are on mice. Here are some highlights:  

• Bacteria called Lactobacillus helveticus can decrease anxiety in mice if they were used in conjunction with a healthy diet.
• This study showed that Lactobacillus reuteri can reduce the likelihood of mice to get infections when they’re stressed.
• This study showed mice given Lactobacillus kefiri CIDCA 8348, which was derived from Kefir grains reduced inflammation.

  In humans too there have been some promising studies showing that probiotics might be used to treat illness. For instance:  

• The bacteria VSL#3 and LCR35 are effective in treating irritable bowel syndrome.
• This paper reveals that the bacteria Lactobacillus helveticus and Bifidobacterium longum can improve our mood and make us more resilient to mild stress.
• This review paper analyzing 20 randomized controlled trials has promising findings for the use of probiotics in treating people with diarrhea.

  But there’s an important point here. It’s extremely unlikely that the probiotics used in the trials I mentioned above are the exact same probiotics that you’re buying at your local shop. In some ways it’s like saying ‘I’m going to take a drug to cure my headache’ without considering what specific drug to take.  

Another important thing to note is that these miniscule microbes have to be alive when you take them. They’re rather fussy and need specific conditions to survive. In fact it’s unclear whether the preparations you buy contain any living organisms after being packed, shipped, unpacked and placed on a shop shelf. Shockingly, this review of fourteen commercially available probiotic products found that only one actually contained the ingredients listed on the label. This review of probiotics for pets found that out of twenty-five products only two actually contained the microorganisms listed on the label. More than one actually misspelled the names of them.  

All this is not to say that probiotics and the fermented foods that contain them definitely won’t work for you. If you’re looking for a probiotic for example to help with your IBS, my suggestion is to read studies showing which types of bacteria are being used in the clinical trails, then hunt down the ones the scientists are using. It may be more expensive but there’s no point in buying something that won’t work.  

Ultimately, my conclusion is that while the microbiome is an exciting new area of research with profound implications for our health, we’re still very much only beginning to understand its application in the real world.  

In all the research that I’ve done I haven’t come across anything to suggest that probiotic foods and supplements could give me adverse health problems, though I’m keen to hear from readers who may have their own experiences. The evidence seems to be mounting to show that it’s is not about trying to get more specific species of good bacteria, but rather about getting a healthy balance of the species. People who lack diversity seem to be vulnerable to disease.  

As for my ill-advised and rather expensive trip to the health food store, I’ve now finished eating my jar of fermented cabbage (it’s actually delicious) and even bought some more. I really enjoyed my sweet, fizzy fermented tea drink for the flavor alone even if the health benefits are unproven. The alcohol content may have had something to do with it, though my husband assured me that I’d have to drink a case of the stuff before it would be considered a ‘big night out’ on kombucha. I won’t be replacing my jar of probiotic supplements, though I’ll continue to look for a product with more robust science behind it.  

Ultimately, rather than focusing too much attention on these foods and supplements, I’ll continue working on cultivating my microbiome diversity by way of a healthy, balanced diet, rich in unprocessed foods and fresh fruit and vegetables.