Ask a Dietitian: A Probiotic Supplement vs Naturally Fermented Food?

Hi Charlotte, which is better: a probiotic supplement or a naturally fermented food like kimchi, sauerkraut or kefir?

This is a question a lot of scientists are still trying to work out.

Probiotics and naturally fermented foods host a distinct population of microbes, which once ingested may interact with the gut microbiome and promote gut health. But it’s hard to test our microbe population. Each of our bodies holds roughly the same number of microbes as human cells – that’s trillions – and a lot of these microbes don’t survive out of our body, which adds another layer of difficulty to studying them.

Basically what I’m doing here is teeing you up to say I don’t have a clear answer.

However, if you push me for one I’d say focus on fermented foods. Both probiotic supplement and fermented food studies show a wide variety of results. Some show that they affect our microbiome, others do not. 

Like with other foods they all affect us differently because we are all different, so it may be that these products are helpful for one person but not for another. In the case of probiotics they appear to be more helpful for those with an altered microbiome, like after a gut illness or a course of antibiotics. 

What I’m trying to say is we’re really at the beginning of gut microbiome research and we’re not even sure if we can link these changes in the gut microbiome to health effects, despite what you might hear.

So why am I recommending fermented foods? Because unlike probiotics they are more than the bacteria they contain. Fermented foods also contain several micronutrients, fiber and other beneficial compounds.

This means fermented foods have benefits beyond affecting the gut microbiome (although they likely do). While I can’t say that probiotics are beneficial if you’re in good health, I can confidently say the opposite for fermented foods.

The taste can take a little getting used to, so try out different food and drink combinations to suit you: kimchi and stir fries, kefir and fruit, and sauerkraut and tofu sandwiches are some of my favorites. Also before you ask, I know beer and wine are fermented, but you can’t count them.

TL;DR

The research for both are in their early stages. Fermented foods have beneficial compounds and effects beyond the gut, so I’d recommend including them in your diet.

Written by: Dan Clarke, RNutr

Reviewed by: Charlotte Marie Werner, MS, RD, CDN