The humble pulse has a powerful impact on human health. Yet pulses’ extensive benefits are not widely known. These seeds are packed full of minerals, vitamins, and nutrients. Pulses also pack a sustainable punch, playing a vital role in global food security.
Each year, the UN invites the world to celebrate this mighty food staple with World Pulses Day. Every day at the Quadram Institute, researchers delve deep into pulses to uncover their role in maintaining good health and new ways to maximise their health benefits.
Pulses are a great source of nutrients
First, what are pulses? Pulses are edible seeds of leguminous plants (legumes). Pulses grow in a pod, and common varieties include chickpeas, lentils, dry peas and beans. These seeds provide a tasty and cheap source of a variety of nutrients.
Pulses are a significant source of vitamins and minerals, such as zinc, folate, and magnesium. Beans, such as soya and edamame, are also an excellent plant-based source of iron. Iron is an essential nutrient in our diet; it’s crucial in making red blood cells, which carry oxygen around the body. A lack of iron can lead to iron-deficiency anaemia. Furthermore, pulses are high in dietary fibre and have a low glycaemic index. These benefits make pulses a beneficial aid in maintaining blood glucose and insulin levels. High-fibre foods are also more filling than processed, low-fibre foods.
Additionally, pulses are a fantastic plant-based source of protein. Protein is generally sourced in our diets from meat, fish, or dairy products. For those on a vegan or vegetarian diet, adding a plant-based source of protein is particularly important. But pulses are also a great staple in the diets of meat-eaters. By adding pulses to mince, soups, and casseroles, you can enhance the texture and flavour of meals. By using less meat, you can make meals cheaper and higher in fibre.
When purchasing pulses, it’s important to check the nutritional label. Pulses are often packaged in tins and may have added salt or sugar. The Food Databanks National Capability (FDNC), based at the Quadram Institute, provides updated data and food composition and intake.
Pulses play an important role in gut health
The UK’s Scientific Advisory Committee on Nutrition (SACN) recommends that adults eat 30g of dietary fibre a day. Yet most UK adults fail to meet this daily target and obtain most of their dietary fibre intake from processed foods.
What is dietary fibre? Dietary fibre refers to the parts of plant-based foods your body can’t digest or absorb. Fibre is key to keeping our digestive system healthy. There are two types of dietary fibre; soluble and insoluble. Soluble fibre supports regular bowel movements by drawing water in the gut, whilst insoluble fibre adds bulk and encourages the movement of material through the digestive system.
Whilst humans have enzymes in the small intestine that can digest starch, these enzymes cannot digest dietary fibre. Instead, dietary fibre passes through the digestive system to the gut microbiota, which can digest it. At the Quadram Institute, we’re delving deep into pulses to gain a greater understanding of their health benefits on the gut microbiome. Aryana Zardkoohi-Burgos is a Wellcome Trust PhD student in the Juge Group:
“For my PhD project, I’m investigating the effect of peas on gut microbiome and human health. I am part of the first cohort of PhD students recruited on the Wellcome Trust funded cross-disciplinary PhD programme EDESIA to advance major aspects of plant-based nutrition and health, from crop to clinic.
My studentship is a collaboration with the John Innes Centre on the Norwich Research Park. I am working with Pisum sativum mutants to study the effect of various raffinose family oligosaccharide (RFO) content on gut health through the use of advanced models of the human gut including human biopsy derived gut-on-chips.”
Pulses may help control blood glucose
Highly processed foods, such as white bread and pasta, often contain a high level of starch. Starch is quickly digested to glucose in the body, causing a significant spike in blood glucose levels. A large body of evidence links long-term consumption of foods that provoke high glycaemic responses to the development of Type II diabetes.
Many pulses, such as chickpeas, peas, beans, and lentils, naturally contain high amounts of resistant starch. Unlike starch, resistant starch is digested slowly and avoids these potentially damaging blood glucose spikes. However, when pulse crops are milled to flour and processed into a food product, this beneficial resistance is lost, rendering the starch highly digestible.
At the Quadram Institute, researchers are bringing the power of pulses to our daily bread. Working with researchers from Kings College London, they’ve derived a new ingredient from chickpeas called PulseON®. The ingredient uses specially-developed milling and drying processes that preserve the cellular structure, making its starch more resistant to digestion.
In a double-blind randomised cross over study, the scientists replaced 0%, 30% or 60% of the wheat flour in a standard white wheat bread recipe with PulseON®. Healthy human participants consumed each type of bread roll type for breakfast in random order on separate days, with no knowledge of which type of roll they were eating. Their glucose levels were recorded using continuous glucose monitors. On average, blood glucose responses to the PulseON® enriched bread were 40% lower than after eating the control bread.
“Incorporating our new type of flour into bread and other staple foods provides an opportunity to develop the next generation of low glycaemic food products to support public health measures to improve health through better diets.
Consumers replacing wheat bread with PulseON® enriched bread would benefit not only from the type 1 resistant starch but also from the higher fibre and protein content.” Dr Cathrina Edwards, Group Leader at the Quadram Institute.
Pulses are a sustainable global food source
Pulses provide planet-kind nutrition, packing a punch against climate change. Tiny but mighty, these humble seeds are a highly sustainable global food source for several reasons. Unlike wheat and rapeseed crops, legumes are nitrogen-fixing. This means they can generate their own fertiliser by harnessing soil microbes, reducing the need for unsustainable synthetic nitrogen fertilisers.
Pulses are also fantastic for improving soil quality. Farmers can exploit symbiotic microbes to fix nitrogen by introducing pulses into crop rotations. These microbes benefit subsequent crops, producing higher yields. Furthermore, pulse crops help boost carbon sequestration. Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide, reducing the amount in the atmosphere.
Pulses also have a broad genetic diversity. A broad genetic diversity is vital in a changing and increasingly challenging climate. Different varieties of pulses can be grown and adapted to different regions and environments worldwide.
With colleagues from the John Innes Centre, Imperial College London, and the University of Glasgow, Quadram researchers have been studying “super peas”; naturally occurring variants of peas that produce a greater amount of resistant starch, but have a lower overall carbohydrate content. The research team point out that it is not just peas that 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 carb-rich foods we consume.
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