Kombucha has become part of the wider boom in gut-friendly foods and drinks. But a major heart-health charity is urging consumers to look more carefully at what these products actually contain.

The British Heart Foundation has warned that some popular gut-friendly products can come with drawbacks. Commercial kombucha may be a healthier alternative to some sugary fizzy drinks, but shop-bought versions can contain added sugar. Other fermented foods, such as kimchi and sauerkraut, can be high in salt.

The warning points to a wider problem. Foods and drinks sold with a health halo are not always straightforwardly healthy. The fact that a product contains potentially active compounds does not prove it will produce a meaningful benefit.

Kombucha is often sold as more than a fizzy drink. Because it is fermented, it is commonly linked with gut health, wellbeing and even stress resilience.

But in our controlled human study, the results were more complicated. Drinking kombucha each day changed some metabolic markers in the body, but did not clearly change how healthy adults responded to acute laboratory stress.

That may sound disappointing to consumers, and to researchers hoping to see a clear effect. But it tells us something important: biological activity does not automatically mean a meaningful health benefit.

The metabolic findings from the study have been published in a peer-reviewed journal. The findings on stress responses are currently under review and should be treated as emerging evidence.

Kombucha is made by fermenting tea and sugar with a mixed culture of bacteria and yeasts, often called a........

© The Conversation