The benefits of fermented foods are reported to be anything from improving your gut health and immunity to reducing risk of chronic disease and improved mood. So, should you be eating them?
What is a fermented food?
Fermentation is a natural process via which live bacteria and/or yeast pre-digest (ferment) the sugar or starch in food and drinks – turning it into alcohol or an acid. This leads to production of vitamins (e.g. folate), beneficial organic acids and other health promoting compounds. Fermented foods include sourdough bread, wine & beer, kimchi, soy sauce, miso, kefir, yoghurt and kombucha.
For example, kefir is a traditional fermented drink made from milk that contains live bacteria, and kombucha is a fermented tea made from tea, sugar, bacteria and yeast (ever seen a SCOBY?).
Humans were consuming fermented foods long before they became trendy, and not always for a health benefit. Fermentation of food helps to prolong shelf-life, and produces carbon dioxide to leaven bread and carbonate drinks – among other functions.
Do fermented foods contain ‘probiotics?’
The word ‘probiotic’ is often used synonymously with ‘fermented food’ – but this is not always the case.
A probiotic is a product (food or supplement) that contains a known live bacteria, in a known amount, that confers a specific health benefit.
A fermented food is simply a food that has undergone fermentation. So, some fermented foods will contain live microbes but they might not fulfill the probiotic definition (AKA we don’t know what type of microbes are in it, or how much, or if they even have a specific health benefit in humans). What’s more – some fermented foods might not even contain live microbes, because they have been killed off in the processing or heating of the food.
Not all fermented foods are created equal.
So, it seems there’s a lot of questions to consider regarding the probiotic effect of certain fermented foods – including whether the microbes survive processing, heating, the supermarket shelf and digestion, and also whether the strain is actually clinically proven for an effect.
Does this mean we shouldn’t bother?
It’s true – overall there is limited evidence backing up the health benefits of fermented foods. These foods might not be a ‘cure all’ but – probiotic or not – they generally provide health benefits outside of a probiotic effect. And just because we don’t know yet – doesn’t mean a benefit isn’t there.
Kefir and probiotic yoghurt probably have the most evidence behind them in terms of a health benefit, and they provide an excellent source of protein and calcium on top of health promoting organic acids and live microbes. Additionally, kombucha makes for a perfect soft-drink swap out, and sauerkraut and kimchi are delicious additions to salads.
If you want to choose a really quality fermented food look for:
- The strains listed on the food (e.g. bifidobacterium and lactobacillus).
- Products that actually list the amount of bacteria present (often as CFU – colony forming units).
- Look for ‘live cultures’ when you purchase yoghurt, or better yet – the actual names of the strains.
- Generally choose refrigerated varieties (shelf stable typically means heating – possibly killing live bacteria).
- Consume yoghurt and/or kefir regularly – Kefir generally has >20 different types of bacteria and yeast (it’s apparently really easy to make yourself – but I haven’t yet tried it!).