As the UK prepares to mark National Bagel Day this Thursday, 15 January 2026, a surprising contender is rising to the top for health-conscious consumers: the sourdough bagel. While perhaps not the traditional first choice, this variety is being highlighted by nutrition experts as a potentially superior option, particularly for those looking to support their digestive wellbeing.
The Secret Is in the Starter
Unlike standard breads and bagels, sourdough is crafted using a live culture known as a starter. This mixture of wild yeast and bacteria ferments at room temperature over roughly a week. According to the University Hospitals Cleveland Medical Center, this natural process allows the yeast to feed on the flour's starches and gluten, unlocking the bread's notable health advantages.
The fermentation generates essential minerals like zinc, iron, and magnesium, which aid in regulating immune function and blood flow. Crucially, this breakdown of complex carbohydrates makes the bread easier to digest. "Fermentation makes sourdough bread easier to digest by breaking down certain carbohydrates that are poorly absorbed," the centre explains, noting it can be a good option even for some with mild gluten sensitivities.
Benefits for Blood Sugar and Digestion
The fermentation process also delivers significant benefits for blood sugar management. As the Mayo Clinic outlines, sourdough has a lower glycemic index than white or standard wheat bread. This means it releases sugars into the bloodstream more gradually, which is vital for reducing risks associated with heart disease, diabetes, and stroke.
Dr. Ulysses Wu of Hartford HealthCare advises shoppers to scrutinise labels. "The best versions have just flour, water, and salt, and ideally use whole grain flour for added fibre," he says. A typical sourdough bagel contains between two and four grams of fibre. Grace Whitmer, a senior clinical dietitian at MD Anderson Cancer Center, notes that this fibre helps stabilise blood sugar, lower cholesterol, and promote a feeling of fullness.
Feeding Your Gut Microbiome
While the live probiotics from the starter do not survive baking, sourdough contains prebiotic fibres. These act as fuel for the trillions of bacteria in the gut microbiome. "A healthy microbiome does more than just support digestion," Dr. Wu emphasises. "Because the microbiome is thought to impact so many different functions, feeding it properly may improve your overall health."
So, as National Bagel Day arrives, opting for a sourdough bagel made with simple, whole ingredients could be more than a tasty treat—it might be a thoughtful step towards better long-term health.
