Probiotics are becoming increasingly popular as pharmaceutical companies and the food industry alike come up with novel ways to deliver probiotics in pills, powders, tonics, foods and drinks. But the evidence for their benefit is not as clear as these labels might suggest.
What are probiotics?
Probiotics are live microorganisms that are thought to be beneficial to human health. They occur naturally in many fermented foods and drinks such as yoghurt, kefir, kombucha, kimchi and sauerkraut. They can also be found in specific supplements sold at the pharmacy.
Probiotics differ from prebiotics, which are effectively food for bacteria. See my article on prebiotics here.
How do probiotics work?
It was commonly thought that probiotics colonise the large intestine, effectively crowding out the “bad” bugs by taking all their food. This makes sense in theory, however we also need to consider that in order to reach the large intestine, these “good” bugs first must make their way through the highly acidic stomach. For many bacteria, this level of acidity is lethal. And the current evidence shows that those bacteria that do survive and make their way to the large intestine do not do so in large enough numbers that will make a significant difference to the overall population. Our gut contains tens of trillions of bacteria, whereas the average probiotic capsule or tub of yoghurt contains somewhere in the order of “hundreds of millions” to “hundreds of billions” of “good” bacteria. So these measures really are a drop in the ocean. Further, our gut ecosystem is constantly changing in response to a variety of factors including diet, medication use, stress, age and the environment. We really need to keep our expectations in check with regards to exactly what probiotics can do.
What can probiotics do?
The current evidence suggests that specific strains of probiotics may be useful in the treatment of some specific conditions: antibiotic-induced diarrhoea, traveller’s diarrhoea, tube-feeding induced diarrhoea and clostridium difficile. But it really needs to be emphasised that specific strains should be used here – it’s not a case of drinking some kombucha every day or popping over to the local low cost pharmacy to purchase whatever probiotic product is cheapest.
There is some evidence that consuming Lactobacillus bacteria, either through fermented dairy (yoghurt, kefir) or capsules, may help to prevent opportunistic infections that can occur secondary to antibiotic use. But again, this research is in its early days.
The bottom line
Currently, it seems that the time you are most likely to get some “bang for your buck” with probiotics is during and after a course of antibiotics. For people who do not suffer from the abovementioned conditions, the current evidence does not support the use of probiotics in the form of pills, powders and supplements in the food supply. That’s not to say that these products are harmful, but if you are looking to spend your money on something with a proven benefit I would look elsewhere. If you want to add some probiotics to your diet, I recommend naturally probiotic-rich foods such as yoghurt, kefir, kimchi and sauerkraut, as these foods are very nutritious, irrespective of their probiotic content. Kombucha can be delicious, but commercial varieties do contain quite a lot of sugar, and in that regard are not dissimilar to a soft drink or fruit juice.
If you are suffering from gut issues, talk to an experienced dietitian before spending your money on expensive supplements that make grand claims that are not supported by the evidence. Yes, dietitian consultations cost money, but when balanced against the ongoing costs of potentially ineffective supplements you’ll still be yards ahead.
