Purple foods have become one of the main 2017 trends in nutrition. Fruit, veg, and even rice of all shades, from lavender to deep violet, and from all regions of the world, from Peru to Japan, have invaded natural foods stores. They are professed to have all sorts of benefits, from cancer prevention to improving the skin. Is there any science behind it, though?
The science of purple
Deep red, magenta, and violet colours in plant foods are conferred by a group of phytochemicals knows as anthocyanines. They occur naturally in plants, and purple foods have long been used to treat various health issues. In particular, anthocyanines are known to have strong antioxidant properties.
Free oxygen molecules are highly reactive; in our body, they are known as free radicals and easily react with proteins and fats, ‘corroding’ them. Thus, free radicals are linked to ageing and many degenerative diseases. Antioxidants, on the other hand, reduce the negative effects of free radicals (though it must be said that free radicals have their own important functions in the body, thus it would be very unwise to neutralize them all).
Antioxidant properties of anthocyanines have been widely studied (see, for example, this study ), and in vitro results are impressive. However, once inside the body, anthocyanine molecules break down very quickly; in fact, they never act alone, combining with other chemicals, so it’s very difficult to study their individual effects .
Some research has also shown that anthocyanines have anti-inflammatory properties – apparently, they block proteins cytokines that produce inflammation . Once again, while scientists have obtained great results in a lab, so far there is no clear proof that it works on real humans.
A further complication is that there are 17 different anthocyanines and many kinds of free radicals and pro-inflammatory proteins, and they all react with each other in different ways. Clearly, much more study is needed!
There are also signs that anthocyanines may promote weight loss (see this study on mice ) and help cognitive function and memory . They may also aid your heart (remember what they say about a glass of red wine keeping your heart healthy?).
A truly global chemical
Anthocyanines are found in fruit, vegetables, and cereals from all over the world: purple sweet potato that comes from Okinawa in Japan (where an incredible number of people live to be over 100 years old), purple corn from Peru, blueberries and blackberries from northern regions, purple asparagus from Italy, açaí berries from Brazil, and even black rice from China (here we are not talking of rice dishes with black squid ink – this ’emperor’s rice’ has such dark purple colour that it seems black)… And more – purple basil and cauliflower, strawberries, red cabbage, aubergines (the peel), pomegranates…
While researchers seek to prove that anthocyanines can indeed keep you young, healthy, and smart, you don’t have to wait for conclusive results: surely, as all fruit and veg, purple foods are good for you. Perhaps it’s not worth paying lots of money for exotic berries and black rice, but it is definitely worth adding more vitamin- and nutrition-packed berries, fruit, and sweet potatoes to your diet.