It may not be a collapse for people who get to choose what they eat, how much they eat, when they eat and how often they eat. But this certainly has a huge impact on the overall human population, where the poorer classes stand at a huge disadvantage with an 8% drop in nutritive value and cannot get supplements and other aids. The existing research and initiatives to fortify staple foods will have to intensify and become more widespread. That's easier said than done.

If you are a wealthy (compared to the average world) western person, they this is not a big issue as you can compensate. If you depend entirely on locally grown plants (most of the world) with barely enough to eat less nutrition is a big problem.