by Dr Rupy Aujla17 Feb 2023
Kale is a dark leafy green vegetable belonging to the Brassica family, also known as cruciferous vegetables. You can spot it in the shop by its long stem and wavy or frilly leaves.
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The first known kale sightings were in the eastern Mediterranean and Asia Minor regions, around 2000 BC. The famous ancient Greek botanist Theophrastus wrote about it in 350 BC, solidifying its place in history.
In traditional medicine, leafy Brassica vegetables were used as a treatment for many ailments such as gastritis, gastric ulcer, rheumatism, bone weakness, ophthalmologic problems, hepatic diseases and anaemia. (Šamec et al. 2019)
Kale contains a complex set of hundreds of nutrients and bioactive compounds that show health-supporting effects.
More than just a list: These compounds interact in complex ways. If extracted or turned into products like supplements or snacks, they are unlikely to have the same effects.
As a cruciferous vegetable, kale is particularly known for its glucosinolates – a unique group of compounds. They are inactive in the whole plant, but after cutting or chewing they are broken down into an active group called isothiocyanates. These are proposed to be important contributors to the health benefits of these vegetables. That’s because they show health-promoting effects in laboratory models, such as:
Multiple observational studies tracking people’s diets over time found that participants with higher intakes of cruciferous vegetables had a lower risk of:
Eating more leafy greens was associated with a 15.8% lower risk of heart disease, as per a meta-analysis. (Pollock et al. 2016)
In the short term, one intervention study found that adding kale and other brassica vegetables to people’s daily diets improved insulin sensitivity and glycemic control. (Thorup et al. 2021)
A higher intake of cruciferous vegetables was associated with a reduced risk of colon, breast, ovarian, gastric and pancreatic cancers. (Tse et al. 2014; Liu X et al. 2013; Han et al. 2014; Wu et al. 2013; Li et al. 2015)
It’s hard to know exactly how much kale and other cruciferous vegetables may provide health benefits. Studies don’t always define what they mean by “higher intake” and doses vary. Usually, we found positive results associated with eating cruciferous vegetables at least once a week or almost every day.
These results show an association but do not prove causation and come with many limitations. So it’s hard to determine whether an ingredient can influence a condition.
Overall: Combined with lab studies and strong evidence about vegetables in general, these results suggest that kale is a good addition to our weekly meals.
Around the world
Kale is used as a deliciously versatile vegetable by Michelin-starred chefs and figures in traditional cuisines around the world:
Too bitter for you? Kale’s bitter taste can be attributed to its glucosinolates. But don’t let that stop you. With a little creativity and some tasty recipes, you can enhance its flavour and make it a delicious addition to your meals.
Kaleventure: Explore the many Kale varieties to find your favourite. If you want a sweeter and mild flavour, try Red Russian Kale. You’ll also find Cavolo Nero, curly kale, and more.
Steam it: When you can, choose steam cooking to preserve a higher amount of bioactive compounds. (Murador et al. 2016)
Try my Butter Bean, Mushroom and Kale Curry on the website.
We have more recipes tailored to your health goals with step-by-step images on the Doctor’s Kitchen app. You can try it for free and there is a free category too. Coming soon on Android. Some of my go-to’s with kale:
This was taken from our brand new newsletter called Seasonal Sundays. Every week, you receive ingredient highlights like this one in your inbox every Sunday. Click here to subscribe + get a free 7-day meal plan.
Mechanisms: Esteve et al. Front. Nutr. 2020
Cooking: Murador et al. Food chemistry. 2016
Cardiovascular disease: Pollock et al. JRSM Cardiovascular Disease. 2016