Kale is one of the brassicas family – including broccoli and cabbage – that is high in detoxifying sulphur compounds called glucosinolates, which have also shown to have high anti-carcinogenic action.
The dark green also shows rich content of fat-soluble antioxidant carotenoids that protect our fatty areas like eyes, skin, liver and brain. They are also mineral and chlorophyll rich and we evolved with plenty of leaves in our diet. The word ‘superfood’ is problematic as is often taken to overdo intake of one or a few foods without balance across a varied spectrum.
Modern humans have very little food variety compared to our ancestors and not eating with the seasons means we repeat foods all year round. Humans have been cooking foods for around 300,000 years and this is how we were able to digest difficult plant fibres as we have smaller digestive tracts and less chewing time to direct energy towards our large brains. Our closest relative, the chimpanzee, can spend up to 14 hours a day chewing!
So the recent trend for juicing oceans of kale can be a bit harsh on the digestive tract as the fibres are neither chewed or broken down with long and slow cooking processes, like in a stew or steamed – my preference for darker greens. Yes, they are broken down by the juicing process, but if this has been chewed, it would also have been mixed with saliva, containing enzymes. Kale is also goitregenic when raw i.e. it negatively affects the thyroid gland, so my advice for those with thyroid issues is to avoid all brassicas veg raw.
Kale is a superfood in the sense that it is highly nutritious, but so is the rest of what nature can provide. We need a variety of foods, so yes kale is wonderfully beneficial but you can’t live on the stuff and I don’t recommend just juicing loads each day. Foods we easily eat raw like celery, cucumber and carrot can be better for juices, but really no food is just ‘ good or bad’ and we need to mix it all up.