Are you a pro at pickling? How about baking sourdough bread or brewing your own kombucha? If the answer is yes, you’ve probably picked up on one of the recent trends promoting fermented foods, which promise to boost your gut health and save both you and the planet from the scourge of food waste.

For the uninitiated, fermented foods include anything that uses bacteria to break down organic matter into a new product. Look around an ordinary kitchen and you’ll almost certainly find something fermented: yoghurt (milk), beer and wine (grain/fruit) or vinegar (alcohol). Not all of these will give you the promised health boost, however, which comes from “live” ferments containing probiotic microbes, usually lactic acid bacteria. In alcohol and vinegar the fermenting bacteria die during the process.

The health benefits of fermented foods are widely promoted. Some advocates, like epidemiologist Tim Spector, suggest the gut microbiome is the key to our health, while others are more cautious: in essence, although kefir is certainly good for your gut, it isn’t a cure-all. Still, the research is ongoing and diversifying: one study has even suggested that probiotics could........

© The Conversation