Broad bean, Vicia faba

Broad beans (also known as fava beans) are the national dish in Egypt and Sudan: ful Medames or Ful Mudammas is a stew of broad beans cooked with spices, often served in a shallow bowl with olive oil and parsley. ‘Mudammas’ means ‘buried’ and the dish is often cooked overnight in clay pots covered with hot ash. The dish is widespread throughout the Arab world and is often served with flatbread for breakfast. In Egypt, Ful Mudammas is also very popular as street food.

Loved by bees and bumblebees

So the broad bean is eaten a lot, but what kind of plant can we harvest it from? Like all other beans, the field bean belongs to the legume family (Fabaceae). However, unlike the common bean, it is not part of the Phaseolus genus, but belongs to the vetch genus (Vicia). Like most vetches, the field bean is an annual herbaceous plant. Unlike most vetches, however, it is not a climbing plant, but has a strong and stable upright stem.

If the plant receives sufficient rainfall, it can grow to a height of over one meter – the largest specimens even reach up to two meters in height. Its stem is square and the leaves are pinnate. However, its flowers are not only visible high up on the stem, but as an early bloomer, the field bean forms its first flowers very early in its development, relatively close to the ground. These are typical butterfly flowers. They are often white, sometimes with dark spots at the base of the petals (these are the ‘wings’ of the butterfly flowers). More rarely, there are also reddish and purple shades in the flowers. Regardless of the colour, the flowers are very attractive to bees and bumblebees. However, they have to exert some force to get through the petals to the nectar. The field bean is a cross-pollinator, but can also fertilise itself. If two different varieties grow in the immediate vicinity, the probability of cross-pollination is very high.

The broad bean forms upright to slanted pods with two to six large seeds. The ripe seeds range in colour from beige to brown to red or dark. The name ‘broad bean’ comes from the fact that the beans are so thick. The young pods and seeds can be harvested fresh or harvested and dried later as mature beans. Depending on the climatic conditions and altitude, broad beans are grown as winter or spring crops.

Where does the bean grow?

Broad beans have a high water requirement. They thrive in soils that retain moisture well or in places with sufficient rainfall. Broad beans can also grow in harsher areas. However, anyone growing broad beans should give the soil time to recover: It should only be sown again in the same place after four to five years.

Like all legumes (Fabaceae), broad beans can accumulate nitrogen in the soil with the help of nitrogen-fixing bacteria. The rhizobia – as these bacteria are called – are found in pin-sized nodules on the roots. Initially, the broad bean itself benefits from this symbiosis; after it dies, the remaining nitrogen is available to other plants as a natural fertiliser. This positive effect of legumes on their subsequent crops must have been noticed by farmers in the early days of arable farming – as early evidence shows.

Cultural history of the broad bean

The broad bean is thought to have originated in southern Central Asia and the Mediterranean region. It was probably first cultivated in the Near East around 9000 years ago. In Europe north of the Alps, it has been cultivated as an important foodstuff since the end of the Bronze Age 2000 years ago. At that time, it also migrated to the North Sea coast and was popular there because it is the only legume that thrives on salty soils near the coast. However, excavations have shown that these early forms of the ‘broad bean’ were not very thick at all.

In the Middle Ages, the broad bean was one of the most important foods and a valuable source of protein throughout Europe. The first varieties with large seeds were also developed at this time. At that time, in the German language, the broad bean was only called ‘bean’. It did not face competition until the 17th century: the green bean and the runner bean were introduced from America, and soon became much more popular with the population. As a result, human consumption of broad beans declined sharply and then were mainly grown as animal feed.

Today, China is the largest producer of broad beans in the world and produces mainly for domestic consumption – exports hardly play a role. In eastern China, broad beans with large pods are mainly grown as fresh vegetables and for further processing in the food industry (e.g. for fermented pastes), while in northwestern and southwestern China, varieties that are more suitable for harvesting dried beans are grown. Unlike in Australia, for example, where broad beans are mainly produced for export, the Chinese broad bean harvest is subject to strong fluctuations in quality. The fungal disease Fusarium and root rot also cause repeated crop failures. There is a wide range of varieties and many old Chinese landraces. Field beans are often grown in rotation with rice in China, but they are also grown in mixed cultivation with kiwi, grapefruit, dates or berries.

One seed – many uses

Almost 50% of a broad bean consists of carbohydrates. Thanks to the symbiosis with rhizobia mentioned above, they contain between 20 and 30 percent vegetable proteins. Broad beans also contain a lot of fiber and water. However, broad beans are poisonous when eaten raw and must be cooked, roasted or otherwise processed before consumption. In addition to their use as fresh vegetables or dried beans, broad beans are also grown in many places as a soil-improving green manure and as protein-rich animal feed. However, broad beans may only make up 5-10 percent of the total feed. Too much broad bean would be toxic to livestock and lead to liver damage and other health problems.

Broad beans can also be dangerous for some people who lack the enzyme ‘G6PD’. They react to two ingredients of the broad bean (vicin and convicin) with headaches, nausea and, in rare cases, life-threatening, jaundice-like anemia. This so-called favism occurs disproportionately frequently in the black population of the eastern Mediterranean region and in African Americans. The content of vicin and convicin can be significantly reduced by roasting, soaking and cooking. Food technologists are working to remove these substances during processing and plant breeding has also produced varieties of field beans with low levels of these two substances.

The lectin L-dopa contained in the broad bean is the starting material for preparations for the treatment of Parkinson’s disease and there is a plant-based pharmaceutical for the prevention and treatment of Parkinson’s disease for which the whole broad bean pod is used. The active ingredient L-dopa is also found in other natural products made from the broad bean. However, the concentration naturally varies and therefore it is not possible to ensure the exact dosage required for Parkinson’s patients is adhered to.

Great potential for the future

In recent years, the green bean has come back into discussion in many places as an alternative to climate-damaging soy imports from the tropics. In fact, the field bean could be a good option for the domestic cultivation of vegetable proteins, especially in places with a harsh climate. Processed forms of field beans such as flour, meal, protein isolate or concentrate have also been increasingly used in the food industry in recent years, for example in meat substitute products, but also in bread and baked goods or desserts. However, research in this area is still in its infancy in many cases and we can look forward to seeing what the future holds.

Sources

Peter Schilperoord: Cultivated plants in Switzerland – field bean. Link.
Yu et al (2023): Production status and research advancement on root rot disease of faba bean(Vicia faba L.) in China. Link.
Botanikus: Field bean, broad bean. Link.
Süddeutsche Zeitung: The miracle beans. Link.
UFOP: The broad bean. Link.
Biology page: Field bean. Link.