Changes in USDA food composition data for 43 garden crops, 1950 to 1999 - PubMed
We suggest that any real declines are generally most easily explained by changes in cultivated varieties between 1950 and 1999, in which there may be trade-offs between yield and nutrient content.
pubmed.ncbi.nlm.nih.gov
It seems the vegetables we are buying in the store aren’t as nutritious as they use to be. I found the study but the news article may be easier to understand.
