Sourdough bread is all about the culture. Photo / 123rf
Sourdough bread is all about the culture. Photo / 123rf
A traditionally made loaf can help with gut health, fibre intake, and blood sugar levels – just be sure to steer clear of ‘sourfaux’, advises Hattie Garlick.
Sourdough sales are soaring and when craft bakers in the United Kingdom were asked for their thoughts on why, 53% pointed to its flavour, while 36% flagged its perceived health benefits.
So what exactly makes a slice of sourdough a cut above more humble loaves?
Sourdough bread is all about the culture. Unlike regular loaves, sourdough is not made with traditional bread yeast.
Instead, explains baker Clare Brown who runs loaf.microbakery in Norfolk, it starts with a culture of just flour and water that ferments, slowly, at room temperature, fed until it contains an alchemical mix of naturally occurring wild yeasts (to create the carbon dioxide bubbles that make the loaf rise) and lactic acid bacteria (to lend it that characteristically tangy taste and lower its pH, more on which later).
A single teaspoon of this culture, or “starter”, can end up harbouring 50 million yeasts and five billion lactobacilli (lactic acid bacteria).
Brown’s bread is then worked into a levain (a small amount of ripe starter that’s been mixed with fresh flour and water) and left for 12 hours to mature, after which the dough is mixed and shaped, before being left overnight, only to be baked the following morning. This is the traditional, slow method and Brown makes batches of organic sourdough loaves, cookies and buns in this way.
Sadly, says Dr Federica Amati, not all sourdough producers are so patient.
“Sourdough is not a legally protected term, so manufacturers can use it on labels regardless of how it was made,” explains the research scientist and the chief nutritionist at nutrition company Zoe.
“This often involves speeding fermentation up with additives, meaning that the process has less of a chance to produce its beneficial effects.”
Her overarching advice? “If you’re buying bread in the shop, make sure to check the label for additives.” Because the old way really is the best way for your health.
Sourdough for gut health
Raw sourdough may be teeming with live bacteria, but most are killed off during the baking process, suggests Eve Kalinik, a nutritional therapist and the author of Happy Gut, Happy Mind.
Nonetheless, if sourdough is made to the traditional method, these bacteria can still help your gut as certain lactic acid bacteria strains within the starter help to “predigest” the bread before it goes into the oven, she explains.
Elements commonly found in bread and which prove problematic for some to digest, such as FODMAP (or fermentable short-chain carbohydrates), are partly broken down.
Sourdough can also be a good source of prebiotics, she says, on which your own gut bacteria feed.
“I switched to eating sourdough about four years ago, and within weeks my energy levels rose and my digestion improved,” says Brown.
One study conducted on patients with IBS concluded that sourdough is less likely to lead to digestive problems than other breads.
Its fermentation process also breaks down some of the acids in bread, such as phytic acid, which may make it easier to digest, explains Amati, meaning that, yes: “people with gluten intolerance or sensitivity to other compounds, like FODMAPs, may find it easier to digest sourdough bread than standard bread”.
Sourdough is still not entirely gluten-free. But hold tight. A team at Colorado State University in the United States is currently studying exactly how different combinations of bacteria and yeast within a sourdough starter can impact the gluten content of a loaf.
If the formula is found, and replicated, it could provide a breakthrough for those with severe intolerances.
“Using specific strains and fermentation conditions, significant improvements were observed related to glycaemic response, satiety or gastrointestinal comfort after bread ingestion.” Photo / Rebecca Zephyr Thomas
Sourdough and blood sugar
White bread can cause blood sugar spikes, leading to tiredness and hunger in the short term and damaging your body’s ability to manage blood sugar in the long term, potentially leading to type two diabetes.
Sourdough (even the white kind) may have an advantage here too, says Amati. “There is some evidence that sourdough may cause less of a blood sugar response than white bread. We don’t know exactly why, but it might be due to the lactic acid produced by bacteria as they ferment, and the changes this makes to the food matrix.”
Much like any other loaf, “if you’re making sourdough from scratch, your choice of flour is the most important factor in how healthy it is: stoneground wholegrain wheat, einkorn, rye and spelt flours all have a higher fibre content than white flour, so they’ll produce healthier bread,” Amati says.
That said, sourdough does have a nutritional edge, she says, since lots of other helpful metabolites (or small molecules like amino acids, vitamins and minerals) are created in the fermentation process, making it more nutritious.
Phytate (or phytic acid) lurking within grains makes it harder for our bodies to absorb their minerals. Research suggests that the lactic acid bacteria in sourdough not only lowers its pH but thereby helps to significantly lower levels of phytate too.
Simply put, it’s complicated. Last year, a systematic review of clinical studies into the relative nutritional benefits of sourdough found that, because sourdough comes in many shapes, sizes and guises: “it is currently difficult to establish a clear consensus with regards to the beneficial effects of sourdough on health when compared with other types of bread”.
Still, some kinds did appear to have quite profound benefits. “Using specific strains and fermentation conditions, significant improvements were observed related to glycaemic response, satiety or gastrointestinal comfort after bread ingestion.” So in Kalinik’s words: “make sure you are buying [or baking] the real deal”.
