Talk to Ireland’s sourdough breadmakers and you quickly learn a surprising fact: often their most devoted customers are people who “don’t eat or can’t eat” bread.

Hang on a second. Surely if you can’t eat bread – if you have gluten intolerance and have a violent reaction to the gluten in bread – then you can’t eat bread, full stop. Right?

And yet it seems that a curious middle ground has opened up. We all have friends and family who “don’t eat or can’t eat” bread. It makes them feel bloated, they say. It makes them feel lethargic. It gives them a rash. They have a sandwich for lunch, and then regret it for the rest of the day.

But everyone who bakes sourdough will tell you they have customers who can not only eat their bread, but enjoy it.

I recently visited sourdough bakers in Ballycastle, up on the north Antrim coast, and all the way down to Tramore in the deep southeast. I’ve been talking to them in Dublin, and in Cappoquin, Co Waterford. Everywhere I go, it’s the same story.

Sourdough breads have an extra ingredient: time

“We have customers who come to us ‘specially for sourdough’,” say Dara and Ciara of Ursa Minor Bakery, a specialist bakery and Économusée near the Giant’s Causeway. In Barron’s of Cappoquin, one of the most venerated traditional bakeries in Ireland, Joe and Esther will tell you the same thing. I have heard the same story at Seagull Bakery in Tramore from Sarah, and from Shane and Charlotte of Dublin’s dynamic Scéal Bakery, based in Glasnevin.

Famous baker

Go to the famous Tartine Bakery in San Francisco, and you will hear the story from Elizabeth Prueitt, partner of America’s most famous sourdough baker, Chad Robertson. As Ms Prueitt writes in her new book, Tartine Everyday: “Chad and I recalled how years ago during our stay in the Savoie region of France, I could eat the bread he was baking with his mentor. Any other wheat-based food in France, and in the States when I returned, caused too much discomfort to be worth eating.”

So, what is going on? After all, isn’t bread always and ever composed of the same ingredients: water, yeast, salt and flour? Yes it is. But sourdough breads have an extra ingredient: time.

Sourdoughs take time to make. You can’t rush them in the way that modern commercial breads are rushed through the baking process. Basically, sourdough needs to be left alone in order to do its thing. And its thing is something quite extraordinary.

What they call most bread in the shops is, in my opinion, not bread but, in fact, still dough

Sourdough fermentation sets up a whole host of funky activity in a batch of dough. Yeasts and bacteria produce carbon dioxide to leaven the bread. Ethanol creates aromas. Organic acids activate enzymes, which set about breaking down the polymers, freeing up sugars and amino acids that lighten the bread and crisp the crust.

And, crucially, sourdough bread partially breaks down gluten, making it easier to digest.

Small wonder that American food writer and campaigner Michael Pollan has been moved to write that sourdough fermentation is “a wonder of nature and culture”.

Still dough

But what happens if the bread you buy hasn’t been given time to do its funky stuff? Shane, of Scéal Bakery, is frank about what we are then buying, and eating: “We should be focusing on the problem of eating masses of un-fermented and under-hydrated dough. And I say dough on purpose, because what they call most bread in the shops is, in my opinion, not bread but, in fact, still dough.”

So, it seems that the healthy answer to a “can’t eat or won’t eat” bread dilemma is to spend your dough on bread, especially slow-proofed sourdough, and make sure not to spend your hard-earned dough on dough.