Bread has been baked for at least 10,000 years, and for 9850 of those years, it was made the same way. Flour was mixed with water, then left to stand until various wild yeasts and lactobacillus bacteria began fermentation. True sourdough still starts this way and produces firm, crusty loaves with a complex tang, owing to that lactobacillus, the same microbe found in yoghurt.

In contrast, white bread – i.e. supermarket bread – is produced using a monoculture of fast-acting lab-grown yeast, resulting in a simpler taste. It’s less nutritious, but most companies add extra vitamins and minerals. Still, sourdough’s acidity helps sneak it into the “low-GI” bracket; white bread is considered high-GI.

Sourdough is often recommended as a “gentler alternative to bread” that’s less likely to cause food intolerances and digestion issues.

That’s because sourdough bread is more digestible than the average commercial loaf of bread made from standard baker’s yeast, with people reporting less bloating with sourdough bread.

The fermentation process breaks down some of the gluten, and that makes it more digestible, especially for people who struggle to digest gluten.

Sourdough is also prebiotic.  Prebiotics are nutrients that feed the beneficial bacteria in your digestive system, which help keep the gut healthy and improve digestion by increasing the availability of nutrients.