The “nutrient collapse” story has been doing the rounds for years, and we’ve been picking at it on the blog for almost as long.
Back in 2009, Jeremy looked at evidence that older crop varieties could contain more minerals, protein and other nutrients than newer ones, and discussed various possible reasons, including the intriguing possibility of a “genetic dilution” effect as breeders selected for yield.
By 2012, we were stressing that the evidence was more complicated than the headlines suggested, and in 2019 we linked to the latest critical review of the evidence by Robin Marles of the Bureau of Nutritional Sciences in Canada.
Now the latest episode of the BBC’s indispensable More or Less podcast asks again whether carrots are becoming less nutritious, prompted by a listener who clearly hasn’t been following our blog, and turns to Dr Marles, now retired, for the answer. Which hasn’t really changed much.
The bottom line is that breeding for yield and other commercially important traits can change the balance of what ends up in the harvest, and that we have historically been much better at measuring tonnes per hectare than what is actually in those tonnes.
