OK, I’ll admit it. In the past I haven’t been resoundingly positive about growing potatoes. That’s because on my tiny plot in Croydon I have found growing the commercial white varieties (think King Edwards) delivers crops with taste and nutrition much like those in the shops, just in exchange for a whole lot more time and effort. Compare this to the almost night and day difference between the knockout flavour of homegrown tomatoes and the sad shop-bought offerings, and in my limited space the choice is clear.
However, there are some caveats. New potatoes like Jersey Royals and the quirky-coloured “heritage” types can be far tastier fresh from the ground than what you’ll find at supermarkets. But perhaps the biggest difference is when it comes to the potential health benefits of the more leftfield varieties. And if it’s these you are after, a growing body of scientific research suggests it doesn’t get any better than the dazzling shades of purple spuds.
Packed full of the same pigments that give red wine and blueberries their potential health benefits, burgundy-hued spuds can boast a whopping three times the polyphenols of the regular white kind. In fact, varieties like “Purple Majesty” or “Violette” can contain gram-for-gram as much good stuff as the berries themselves, according to Colorado State University. My own growing trials found they produced yields up to 10 times that of blueberries per unit of space, all for a fraction of the cost of a blueberry bush.
According to the Journal of Agricultural and Food Technology, adding a 140g serving of purple potatoes twice a day to the diet of overweight, middle-aged subjects caused their blood pressure to drop almost five points within just a month – despite the fact that almost 80% of them were already on antihypotensive drugs. Such a fall could “decrease the risk of stroke by 34% and of heart disease by 21%” according to Barts and The London School of Medicine. These potatoes added 280 calories to their daily diet, but the subjects in this trial didn’t gain weight either.
OK, this may be just one study and we need a lot more research before solid conclusions can be drawn, but these results do contribute to a growing weight of evidence behind the benefits of going for purple. As these varieties are widely sold in the seed catalogues yet are still a rare find in the shops, to me it makes the case for picking them over the ubiquitous white ones a pretty strong one.
Considering that they are also just as easy to grow, taste great and provide truly hypnotic colour, it is hard to see a clear downside.
Email James at james.wong@observer.co.uk or follow him on Twitter @Botanygeek
How To Eat Better by James Wong is published by Mitchell Beazley on 6 April at £20. To order a copy for £17 go to bookshop.theguardian.com
