OUR weekly vegetable box has been getting heavier of late with the arrival of more cruciferous vegetables. Black kale, green kale, January King cabbage, purple cabbage, cauliflower – we’ve had them all. Well, nearly all. We haven’t started on the January King cabbage yet, and half the purple cabbage is in a jar slowly transforming into sauerkraut.

Cruciferous vegetables get this name from their flowers that resemble a crucifix. They’re also commonly known as brassicas, and the group includes cabbage, cauliflower, rocket, watercress, radish, bok choy, kale, mustard greens and that seasonal favourite: Brussel sprouts.

Each one of these vegetables is an absolute powerhouse of nutrition; packed with vitamins A, C, E and K; folate, calcium, potassium, fibre, powerful antioxidants (including lutein, a vital nutrient for good vision), and a less well-known nutrient – sulphoraphane.

Sulphoraphane, as you might have guessed, contains sulphur, and is the compound that gives these vegetables their pungent aroma. It is also the nutrient responsible for many of the brassicas anti-cancer and detoxification properties.

Sulphur plays a key role in helping the liver process and detoxify hormones and many of the potentially harmful substances we encounter day to day. For example, medications, alcohol, and pesticides from foods. Without sulphur the liver would struggle to do its job properly.

Animal and laboratory studies have provided strong evidence of sulphoraphane’s ability to protect DNA and inhibit tumour growth, and various human studies have shown links between brassica vegetable consumption and reduced cancer risk. Food studies are difficult in humans because of the many other confounding factors that can influence the results, but it is widely acknowledged that a diet rich in unprocessed wholefoods and colourful vegetables – including the brassica family – is helpful for reducing the risk of cancer and chronic diseases.

Sulphoraphane is produced by a chemical reaction that occurs when a brassica vegetable is chopped or sliced. I recently heard a well-respected natural health expert recommend people chop their cruciferous veggies and let them rest for ten mins to allow the sulphoraphane to develop. Chewing also activates its formation – another good reason to chew properly!

If you find them a bit difficult to digest, add a scattering of caraway or aniseed seeds when cooking; these herbs are excellent digestive aids and can help reduce wind and bloating.

Sally Duffin is a Registered Nutritionist (MBANT). Find her online at nutritioninyork.co.uk or join the Facebook group Nutrition in York.