Runner beans grown too big.

www.theguardian.com/lifeandstyle/2010/aug/28/alys-fowler-runner-beans#:~:text=You%20can%20eat%20them%20fresh,or%20trying%20to%20poison%20them.

As long as they are cooked they are fine.

It seems that there are different opinions about the toxicity of the humble runner bean ‘beans’ we use them as seeds for the following year.

We grow tomatoes and I sometimes make a tomato puree and mix with cooked beans - runner and/or the beans from inside French beans - these escape too! I transfer to jars and bottle - use pressure cooker to sterilise. Then I have beans in tomato sauce ready to use ìn chili or stew. You could freeze, alternatively.

Almost all organisms contain lectin a tye of protein that binds to certain carbohydrates. There are many types of lectin, some completely safe, some extremely toxic. Perhaps, the most well known is ricin obtained from the castor bean c/f the story of Georgi Markov, the Bulgarian dissident writer and journalist who died after he was attacked by a man with an umbrella rigged to inject a poison ricin pellet under Markov's skin.

Drying (of any substance) removes water and other liquid properties e.g natural oils, to produce a concentrate. So a dried bean would contain a more concentated level of protein than an undried one.

One particular lectin is called phytohaemaglutinin. Phyto - of a plant; haema - blood; glutinin - effectively a sticky binding agent as in gluten. Phytohaemaglutinin causes blood cells to bind or clump together.

Phytohaemaglutinin is found in the highest concentrations in uncooked red kidney beans and white kidney beans (cannellini) and it is also found in lower quantities in many other types of green beans and other common beans, as well as broad (fava) beans.

Measured in haemagglutinating units (hau), a raw red kidney bean may contain up to 70,000 hau, but this is reduced to between 200 and 400 hau when properly cooked. White kidney beans contain about a third of those levels, green and other common beans even less. Fava beans have levels of around 5-10% compared to the red kidney bean.

Very informative Farmor * thanks.

In the past I have dried and saved bean seeds for the following year. I have never thought of eating them, well I will now. I can perhaps try in a chilli con carne / minestrone soup?

Here's a reference - no mention of toxin.
hort.extension.wisc.edu/articles/scarlet-runner-bean-phaseolus-coccineus/#:~:text=The%20white%20or%20multicolored%20seeds,long%20soaking%20and%20cooking%20time.

The beans inside runner beans are not the same as red kidney beans, which are the ones with toxin. They may look a bit similar, but a different species of bean. I've been extracting and eating the beans inside overgrown runner bean pods for years with no ill effects. They need to be boiled for 10 min or so anyway.

I believe that all runner beans contain the toxin, can’t be eaten raw and have to be well cooked.

The toxin doesn’t go from the dried until they are cooked.