New knowledge about plant proteins: Faba beans are a good complement to Finnish diets

A study conducted by the University of Helsinki’s Leg4Life project found that faba beans contain inadequate amounts of the essential amino acids histidine and tryptophan, and below-optimal amounts of sulphur amino acids. The researchers state that the digestibility of faba bean protein in the human body is fairly good.

“Knowledge about the digestibility and bioavailability of plant-based proteins in the human body is scarce. Although plant proteins are, on average, of poorer quality than animal proteins, a combination of legumes and cereal products as protein sources provides an amino acid composition satisfying the requirements of the human body. Although the amino acid composition of soya itself is excellent, using more domestic legumes would be environmentally advantageous,” explains Docent Suvi Itkonen of the University of Helsinki’s Faculty of Agriculture and Forestry.

Multidisciplinary and international collaboration sheds light on faba bean protein digestibility

The protein and amino acid digestibility of faba beans cultivated in Finland was studied on French volunteers in collaboration with AgroParisTech. The volunteers each consumed a faba bean meal, after which the flow of the food mass in the gastrointestinal tract was monitored for eight hours. Samples were collected from the end of the small intestine to determine protein and amino acid concentrations.

“This research method based on nitrogen isotopes allowed us to examine separately the digestibility of total protein and individual amino acids in the small intestine, as well as their absorption into the bloodstream.All amino acid should be treated as an individual nutrient because different amino acids have specific functions in the body,” says Itkonen.

“This study is an excellent example of the power of multidisciplinary and international collaboration. The project combined the University of Helsinki’s knowledge of plant production and soil sciences as well as food and nutrition sciences with the unique methodological expertise of the French partners. Led by Frederick Stoddard and Asko Simojoki, researchers at the Department of Agricultural Sciences were responsible for the study’s challenging cultivation of faba beans fertilised with the rare isotope nitrogen-15. The processing of the beans into test meals was planned and carried out at the Department of Food and Nutrition. The digestibility study itself was conducted in an international setting during Itkonen’s research visit to France,” notes Associate Professor Anne-Maria Pajari, the Leg4Life project leader. 

Faba beans are increasingly used as raw material for processed plant protein products. As the popularity of plant-based diets increases, researchers stress that more scientific knowledge is needed on the digestibility and bioavailability of plant proteins. The Nordic Nutrition Recommendations updated last year also emphasise a predominantly plant-based diet from both health and environmental perspectives.

Original article:

Itkonen ST, Calvez J, Airinei G, Chapelais M, Khodorova N, Sahaka M, Benamouzig R, Stoddard FL, Simojoki A, Pajari AM, Gaudichon C. True ileal amino acid digestibility and protein quality of 15N-labeled faba bean in healthy humans. The Journal of Nutrition 2024, 154, 1165-1174 https://doi.org/10.1016/j.tjnut.2024.01.030

Leg4Life (Legumes for Sustainable Food System and Healthy Life) is a multidisciplinary project funded by the Strategic Research Council, an independent body within the Research Council of Finland. The project aims to achieve a comprehensive societal change towards a healthier food system and climate-neutral food production and consumption by increasing the use of legumes. The project investigates legumes that thrive in Finnish boreal conditions through five extensive work packages covering the entire food chain from field to fork.