Super pea reduces type 2 diabetes risk

Wednesday, 28 October 2020

A new study suggests that a wrinkled ‘super pea’ helps to control blood glucose levels and reduces the risk of type 2 diabetes.

The research, from Imperial College London and the University of Glasgow, suggests incorporating the super peas into foods, in the form of whole pea seeds or flour, may help tackle the global increase in type 2 diabetes.

Super pea reduces diabetes risk

The work, published in the journal Nature Food focused on a naturally occurring type of pea. Unlike regular (smooth) peas, they contain higher amounts of ‘resistant starch’, which takes longer for the body to break down.

The study reveals that compared to eating smooth peas, wrinkled peas prevented ‘glucose spikes’ – where blood glucose levels rise sharply after a meal. The same effect was seen when consuming flour made from wrinkled peas incorporated in a mixed meal.

According to the researchers, this could be important as frequent, large glucose spikes are thought to increase the risk of diabetes. They add that flour from their ‘super peas’ could potentially be used in commonly consumed processed foods which, if eaten over the long term, could prevent these glucose spikes.

Resistant starch

Dr Katerina Petropoulou, first author of the research said: “Despite campaigns to promote healthy eating, type 2 diabetes diagnosis rates continue to rise.

An alternative dietary strategy to maintain normal blood glucose rates among the population is to improve the composition of commonly consumed foods.

There is a lot of evidence that diets rich in a type of carbohydrate called resistant starch have a positive impact on controlling blood glucose levels, reducing susceptibility to type 2 diabetes.”

About the super peas

The peas used in the research are similar to the frozen peas you can buy in the supermarket. But, the ‘super pea’ – wrinkled peas produce more resistant starch, and have a lower overall carbohydrate content.

Starch is a compound that the body breaks down to release glucose, but resistant starch is broken down more slowly, so that glucose is released more slowly into the bloodstream, resulting in a more stable increase rather than in a spike.

About the research

Over a series of experiments, the team gave healthy volunteers a mixed meal including 50 grams of wrinkled peas, and in a series of control experiments gave them regular ‘smooth’ peas.

Working with the University of Glasgow, researchers also added a tracer molecule to the peas, so that they could trace how they were absorbed and digested by the human gastrointestinal tract.

They repeated the experiments using flour made from wrinkled peas or control peas. To further investigate the impact of long-term consumption they recruited 25 volunteers and asked them to consume pea hummus and mushy peas (made from wrinkled or control peas) for a period of four weeks.

Professor Gary Frost, lead author of the study said: “The ‘super pea’ contains a naturally-occurring variant gene that means they are high in resistant starches. These starches are not completely digested in the upper parts of the digestive tract and are available for fermentation by bacteria in the colon.”

Previous research from the same group has suggested that, as these bacteria ferment the starch, they produce compounds called short chain fatty acids. These compounds in turn help boost the function of cells that produce insulin, which helps control blood glucose.

Reducing blood glucose spikes

Further tests showed that the way that the peas were prepared and cooked affected how quickly they were digested. Researchers also showed that there were significant benefits to our gut microbiota because of the fermentation process taking place there.

Professor Pete Wilde said: “This study has shown us that by preparing these peas in certain ways we can further reduce blood glucose spikes, opening up new possibilities for making healthier foods using controlled food processing techniques.”

What’s next?

The researchers are now planning further trials involving volunteers with early stage type 2 diabetes. This will also involve a major pea breeding programme with help from industry partners to develop more ‘super peas’ with the resistant starch.

They will also explore the genetic background of commonly consumed pulses (beans) to see if similar genetic variation in other crops shows the same positive effects on health.

The study authors point out that it is not only peas which have the resistant starch mutation. Other research is focusing on breeding the mutation into staple crops, such as rice and wheat.

With modern genomic tools there is the potential for discovery or generation of the mutation across a range of seed and grain crops – which make up many of the carbohydrate-rich foods we consume.

Professor Domoney added: “Longer term it could become policy to include resistant starch in food. We have precedents for this kind of intervention, such as iron being added to bread to tackle anaemia. It could potentially be policy that food should contain a certain amount of resistant starch to tackle type 2 diabetes and other metabolic illnesses.”

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