Are fermented foods like kimchi really that good for your gut?

Humans have been fermenting food and drink for at least 13,000 years – and touting the health benefits for nearly as long. But despite our long history with them, we are only beginning to determine whether these foods are actually beneficial for our health.

Unlike our ancestors, however, we now know how fermentation works: microbes such as certain yeasts and bacteria break down sugars in grains, fruit, vegetables and dairy products in a way that prevents them from spoiling and produces unique flavours. But what does this mean for our health?

Numerous studies have linked fermented foods – particularly dairy versions – to a reduced risk of heart disease, type 2 diabetes and obesity. For instance, a 2023 study involving more than 46,000 adults living in the US found that eating fermented foods was associated with lower blood pressure, body mass index and waist circumference.

But much of the research lumps all kinds of fermented foods together, and given the health halo around these products, we know that people who consume them probably tend to look after their health in other ways too. Both of these factors make it difficult to determine what is actually providing any observed benefits.

Benefits of yoghurt

That said, the case is strongest for yogurt. Many large studies have linked its consumption to improvements in immunity, bone density and longevity and to a reduced risk of cardiovascular disease and high blood pressure. Yet determining cause and effect from these observational…