How scientists plan to boost fibre in white bread

Scientists investigating ways to create healthier white bread and wheat-based products have revealed plans to modify the starch in wheat.

Researchers at government-backed The Quadram Institute in Norwich are hoping to modify a type of starch found in wheat grain so it behaves more like dietary fibre and is digested at a much slower rate.

The plans, which involve enhancing the nutritional value of wheat and increasing its fibre content, form part of the Institute’s £40m science strategy, which aims to provide better understanding of how food influences health, as well as identifying ways to combat diet-related conditions including obesity and type 2 diabetes.

Currently, white bread does not make the consumer feel full for long – which can lead to overeating – while the starch it contains is quickly digested, resulting in blood sugar spikes that the body can only eliminate by storing as fat.

Such spikes can stop the body producing enough insulin to get rid of blood sugar, leading to type 2 diabetes.

The overall aim of our research is to improve the quality of starch in wheat in a way that leads to improvements in human health,” research leader Dr Brittany Hazard told British Baker.

Below, Dr Hazard tells us more about the programme.

Why is this work important?
Wheat is a staple crop – globally it provides around 20% of the calories consumed by the world’s population. If you can change the wheat that so many people eat in a way that boosts health, you can make a real difference to some of the diet-related conditions that affect global society.

Obesity has tripled since 1975 and, in the UK, more than half of the population is obese or overweight. Obesity is linked to greatly increased chances of developing colon cancer, high blood pressure and heart disease, and type 2 diabetes. This is placing a huge strain on healthcare services. Poor diets, especially ones based on energy-dense convenience foods, are a major contributor to this.

People eat 750 calories-worth of wheat-based foods every day and white bread is a staple food for many

So if we can improve diets, we can address some of these problems. This can be done by encouraging people to eat better diets. In the UK, people eat about 750 calories-worth of wheat-based foods every day, and white bread is a staple food product for many. This means that any improvements we can make have the potential to make a large impact.

How do you propose to make the bread healthier?  
We’re trying to alter the starch structure in wheat, so that the starch isn’t broken down as easily by the body. This resistant starch affects health in different ways. Resistant starch is a component of dietary fibre and there is a lot of evidence that consumption of fibre is associated with reduced risk of diabetes, heart disease and colon cancer. Most of the starch in standard white bread is broken down into sugars quickly, in the small intestine. This, in turn, releases sugars into the body quickly, causing a sugar spike. Also, by slowing down the digestion of starch, the body feels fuller for longer. It links to the hormone signalling system in the body, so maybe people are less tempted to have a snack in-between meals.

Crucially, resistant starch isn’t well digested by the small intestine, but passes into the large intestine. In this part of the digestive system we host a large community of microbes, called the microbiome. At The Quadram Institute, we have a major programme of research that’s looking to understand how the microbiome benefits health. This is a hot topic in science and health research at the moment, with the microbiome being linked to a range of different conditions. We know that resistant starch that reaches the colon is a key source of nutrition for the microbiome. This keeps the microbial population healthy, but also releases vital molecules that we think benefit our health.

What is the current problem with starch quality?
There isn’t a particular problem with starch quality itself, but rather consumers getting too many calories while at the same time not getting enough fibre. It’s recommended that we eat 30g of fibre each day as fibre is linked to reduced type 2 diabetes, cardiovascular disease and colon cancer.

Currently, the average person in the UK eats just 18g. A slice of white bread has about 1g of fibre, while wholemeal has about 3g. But it’s very apparent that consumers prefer white bread, for a number of reasons, including taste, but also price. Our challenge is to develop wheat and products derived from that wheat that match these consumer preferences, but deliver the health benefits from higher fibre and resistant starch.

Are there any other types of wheat/grains that can be used to limit the impact? If so, which ones?
A good option for consumers right now is wholemeal, but in the future we hope to produce wheat varieties carrying resistant starch traits. That way we could have white flour and bread with increased fibre too.

Why is this research important for bakers? 
The increasing consumer awareness of health benefits associated with fibre will increase demand for healthier foods. Developing new raw materials that bakers can use in their products will add value and meet consumer demands.

Who will you be collaborating with as part of the research?
The project is a collaboration between The Quadram Institute and The John Innes Centre, but also involves crop breeders, seed companies, growers and food producers. It’s not just a case of developing wheat with more resistant starch – we need to know if these new varieties carry any yield penalty or affect other qualities of the flour. We need to see whether processing and baking affect the levels of resistant starch, as it’s the levels in the final loaf that matter. And, importantly, we need to be able to assess whether these new wheat starches have an impact on health.

Who is funding the research?
The funding for the programme is primarily through the Biotechnology and Biological Sciences Research Council (BBSRC), part of UKRI, which is itself funded through the science budget by the Department for Business, Energy and Industrial Strategy (BEIS).

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