A raft of probiotic products — pills and chewable tablets, milky supplement drinks, yoghurts and even gourmet soft cheeses with specially selected good bacteria added — are sold on supermarket shelves. Some mention general health benefits, but others say they are specially formulated to help with a specific condition, such as the tummy upsets that can accompany antibiotic use.

As well as wiping out the infection the doctor has prescribed it for, an antibiotic may take out all bacteria — good as well as bad. 

When you eat or drink a probiotic product, its health-promoting bacteria may rebalance the bugs in your gut and prevent nasty troublemakers, which might cause tummy upsets and other issues, from taking hold.

So how interchangeable are they — will a few slices of probiotic brie atop a cracker help a patient taking antibiotics as well as a specially designed tablet would?

A review of clinical trials last year found probiotics did not offer any demonstrable advantages for healthy adults.
A review of clinical trials last year found probiotics did not offer any demonstrable advantages for healthy adults.

When you look at the nutritional or supplement information, you’ll find probiotic products contain different species of bacteria, and even specially designed strains. You can find tablets boasting 10 or more different species or strains.

While it’s easy to think one type of microscopic bug must be similar to another, the reality is different. Bacterial species can be as different from one another as a flamingo is from a pine tree.

This means their impacts on human health are diverse — scientists say if they find a benefit (or harm) in one species, the discovery is relevant to that species alone.

Though probiotic products tout the research behind them, and often describe their health benefits as “clinically proven”, the scientific consensus is far behind what the claims say. 

Of the probiotic strains you’ll find on the shelves, experts have only expressed some confidence in 2 if a person taking antibiotics wants to avoid tummy troubles: Lactobacillus rhamnosus and Saccharomyces boulardii.

According to independent healthcare reviewer the Cochrane Collaboration, there’s “moderate” evidence these keep bad bacteria in check for children using antibiotics.

To find these, you’ll likely need to look in the supplement section. Of the 22 probiotic dairy products we looked at in supermarkets, we couldn’t find any containing either of these 2 strains.

Supplements containing them don’t come cheap. The lowest-priced product we found meeting Cochrane’s recommendations cost $32 for 30 capsules containing L. rhamnosus.

If you do take a probiotic supplement alongside antibiotics, feel free to keep this temporary. A review of clinical trials last year found probiotics did not offer any demonstrable advantages for healthy adults.

Anyone with a seriously compromised immune system should avoid probiotics unless they have checked with their doctor.

Regulation

Last year, New Zealand introduced a system pre-vetting health claims on foods. If a company wants to market its probiotic yoghurt or cheese with a health claim, it has to specify the claim and provide evidence to the Ministry for Primary Industries (MPI) to get it approved.

No probiotic food has had a health claim approved by MPI. In Europe, the regulator is even stricter. It considers the term probiotic to be a health claim in and of itself. The European regulator has not yet been provided enough scientific evidence to convince it to allow any product to call itself a probiotic.

Here, if manufacturers label their products (such as fermented milk drinks) dietary supplements, they are subject to different rules and don’t have to supply evidence to back up their health claims before products go on the market — yet.

Legislation before parliament will require supplement companies to publish a summary of the scientific evidence to support their health claims before they can sell a product. A newly created authority can then investigate products should it choose. The system will allow some checks on supplements making health claims. But we think any products claiming to help or prevent health conditions should be vetted to offer more protection for consumers.