Kale is significantly better at preventing cancer than other vegetables. This is the result of a joint study by the University of Oldenburg and Jacobs University in Bremen. In their search for the perfect kale, scientists analysed around 40 varieties of the vegetable from Germany, Italy and the USA. The results are now to be used for new kale varieties.
Kale has been a cult vegetable for decades - especially in north-west Germany. For a long time, it was mainly considered a hearty winter vegetable in this country. However, more and more people are now discovering that kale can be used in a much more versatile way in the kitchen. Together with other types of fruit and vegetables, it is used to make healthy green smoothies, for example. Kale is also becoming increasingly popular worldwide.
Two research groups led by Oldenburg biologist Prof Dr Dirk Albach and Bremen chemist Prof Dr Nikolai Kuhnert have set out in search of the tastiest and healthiest kale. They were looking for types of kale that are particularly low in bitter substances and particularly rich in cancer-preventing substances. They made an astonishing discovery: "Until now, broccoli was considered the best anti-cancer vegetable," says Kuhnert. "So we were all the more surprised to find that some types of kale contain ten times more cancer-preventing substances than broccoli."
These types of kale owe this special effect to a high proportion of so-called glucosinolates. These are the plant's own substances that protect kale from voracious insects. They make it a dangerous or even deadly meal, especially for hungry caterpillars. Humans, on the other hand, can benefit from these substances. This is because the glucosinolates are converted into mustard oils when the kale is chopped. "Some of these mustard oils have been shown to have a chemopreventive effect. They can therefore help to prevent cancer," says Kuhnert. North German kale varieties in particular, such as Frostara, Neuefehn and Rote Palme, had a high proportion of these particularly healthy mustard oils. The results of the study were recently published in the renowned Journal of Agriculture and Food Chemistry. The lead author is Christoph Hahn, a doctoral candidate at the University of Oldenburg.
However, it may still be difficult for consumers to recognise whether they have just put particularly healthy kale in their shopping basket. This is because, unlike potatoes, the variety name of kale is usually not mentioned in the shops. Nevertheless, consumers could benefit from the research results in the future. Biologist Albach and his team are currently working on crossing the tastiest and healthiest varieties in order to combine the best characteristics of different types of kale. The aim is to create a new variety of kale that has the potential to establish itself as a standard on the market: "However, eating habits must also change for this to happen, as the healthy ingredients are best preserved in salads," says Albach.
Interest in the research results was so great in the north-west that the project was partly financed through crowdfunding. Oldenburg Tourismus und Marketing GmbH organised a corresponding online and postcard campaign, which has so far raised almost 15,000 euros.