Dr Vanessa Kimbell
When considering how to nourish ourselves through winter this year, we wanted to look beyond simple sustenance. Food doesn’t just fuel the body, it can shape our mood, make us more resilient and feed the soul. It was this holistic approach that led us straight to our friend Dr. Vanessa Kimbell – baker, award-winning author and nutrition expert. A pioneer in the field of bread nutrition, Vanessa is founder of The Sourdough School and inventor of the BALM protocol (Baking as Lifestyle Medicine), a transformative approach that redefines bread as a vehicle for physical and mental wellbeing. We knew that if anyone was going to help us eat right this season it would be Vanessa. So we asked her to share how to choose the best loaf to support good health – especially during the winter months.
This winter has felt particularly long and the seasonal changes are not neutral territory for human physiology. Metabolic demand rises as daylight falls and there is less sunlight, fewer fresh plants available, colder temperatures, and a higher burden of infection circulating in the population. We sit much more, especially with this persistent rain and the darker days that reduce outdoor movement. Comfort eating increases. Mineral status drops. Low-grade inflammation creeps in and for many people, mood follows the same downward curve.
The gut follows it too. There is growing evidence that the composition and function of the gut microbiome shift seasonally, often tracking dietary diversity – and in winter, as diets narrow and plant intake falls, that diversity is at risk. Fewer different seasonal plants means fewer different fibres, which means fewer different microbial species being fed. The ecosystem simplifies. And when microbial diversity drops, so does the resilience of the immune system that depends on it.
In that context, bread stops being “just carbohydrate”. It becomes either a problem or a powerful support.
For me, this understanding arrived through experience before it arrived through research. In my early twenties, following a particularly difficult year, I found myself in a deep winter depression. It was January. Cold, dark, relentless. What drew me out of that period was baking. More specifically, it was bread.
I did not have the language then to explain what was happening all those years ago, but I could feel something shifting – in the rhythm of the work, in the steadiness it brought. Decades later, with the benefit of clinical research, I understand why. Bread, when made properly, is not a filler food. It is structural. It is one of the most powerful fibre delivery systems we have. When chosen and eaten well, it feeds the gut microbiome, supports mineral intake, stabilises blood sugar, and helps regulate immune activity. In winter, those functions matter more than at any other time of year.
Rye & Barley Sourdough, Brown Sourdough and Wasteless Sourdough
Choosing the Right Bread
The reality is that we have lost our understanding and respect of bread as it was industrialised. We devalued bread. Economic pressure pushes people towards cheap calories, and bread is often judged by price rather than by process. Sourdough, wholegrain and long-fermented breads tend to cost more, but price tells you very little about the real value of the bread. What matters is not the label or the colour of the loaf, but rather what has actually happened to the grain.
The first thing I look for is wholegrain, because this delivers all of the component parts of the wheat in its entirety: magnesium, selenium, zinc, potassium and B vitamins. These are minerals and cofactors the immune system relies on, particularly in winter.
Magnesium deserves particular attention. It is involved in over three hundred enzymatic processes in the body, but its relevance in winter is specific: magnesium is involved in neurotransmission, including GABAergic signalling, the pathway most associated with calm and sleep. When intake is chronically low – and in the UK, dietary magnesium is frequently inadequate – sleep and stress tolerance often worsen. Wholegrain bread is one of the most consistent everyday sources of magnesium we have. It is quietly structural, which is exactly what winter demands.
One of the most important things about fibre, especially from wholegrains, is that it actively helps keep the immune system steady. When your gut microbes break fibre down, they make short-chain fatty acids. These support the gut lining, help immune responses stay balanced, and are associated with lower inflammation. I often describe the role of SCFAs, when it comes to calming your immune system, as behaving like both the referee and the stewards at a football match: keeping order on the pitch and in the stands.
Why is calm needed? Most people think a strong immune system means one that reacts loudly and fast, but what you really want is an immune system that knows when to act — and when to stay calm. If the immune system becomes overactive, it stops distinguishing properly between real threats and harmless stimuli. In practical terms, that can mean:
• Allergies – reacting to pollen, foods or dust as if they are dangerous.
• Autoimmune conditions – attacking your own tissues, such as in thyroid disease, coeliac disease or rheumatoid arthritis.
• Chronic low-grade inflammation – a persistent background “alert state” that contributes to fatigue, metabolic dysfunction, vascular issues and mood changes.
An overactive immune response is a bit like a smoke alarm that goes off every time you make toast. It’s still working — but it’s not calibrated.
Another reason wholegrain matters for immunity is the winter vitamin D drop. Vitamin D helps your immune system switch on when it needs to, but also switch off again, and it supports the gut lining that acts as part of your immune defence. In winter we make less vitamin D because we get less sunlight. Researchers are also finding that vitamin D signalling in the gut and the mix of microbes living there appear to influence each other. The science is still evolving, but it helps explain why, by the end of winter, it’s smart to support your gut with fibre-rich, fermented bread and include vitamin D-rich foods as part of how you eat.
But wholegrain alone is not enough. Diversity matters. Rye is wonderfully rich in arabinoxylans and polyphenols. Barley provides beta-glucans known to support cardiovascular health and blood sugar regulation. Seeds add excellent value when they are incorporated in a way that respects digestibility – milled, fermented, or processed within the dough so that they are biologically accessible rather than decorative. The point is to counter winter’s narrowing of the diet with deliberate breadth. A bread made with six, eight, ten different grains and seeds is not a gimmick. It is a direct response to the seasonal loss of plant diversity on the plate.
Seeded Sourdough and Hazelnut & Walnut Sourdough
Fermentation: Biology, Not Style
Lots of people talk about sourdough as though it is a fashion choice. In my work, fermentation is a biological transformation. Fermentation breaks down phytates, increasing mineral availability. It modifies gluten proteins. It changes how starch behaves in the body, lowering the glycaemic response. You are not just eating bread; you are eating the result of time, microbial activity and enzymatic work. This is why properly fermented bread delivers more nutrition per bite.
This is, in particular, where the distinction between real sourdough and industrial sourdough-style products matters. Many commercial sourdough breads use selected yeasts and bacterial strains that create acidity and flavour but stop short of full fermentation. Heterofermentative lactobacilli – species such as Fructilactobacillus sanfranciscensis – are frequently absent from these products, in part because they increase sourness and accelerate protein degradation in ways that are harder to control at scale. The result is a bread that looks right and tastes acceptable, but has not undergone the full metabolic transformation that makes traditional sourdough behave differently in the body.
The colour of bread is not a mark of integrity either. You have to look at ingredients, ask questions, and engage with the process. When I am not baking myself, I go to a real bakery. I ask the staff which bread they eat themselves, how long fermentation lasted, where the flour came from. These are not affectations. They are questions about biological readiness.
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As bakers, we know bread can be so much more than just an ordinary staple or comforting carb – it holds remarkable potential for complexity, flavour and storytelling. But understanding how the right bread can nourish us from the inside out deepens our relationship with this humble food further. We’re so grateful to Vanessa, whose research continues to guide our approach and recipes.
For more advice on how to nourish yourself this season, don't miss Vanessa’s next article on what to eat with your bread to reap its full health benefits, plus her recipe for a delicious, gut-friendly butter. You can also read more about Vanessa’s approach through her Sourdough School baking books, including her forthcoming title, PROVEN.
Photography by Joe Westley
