Several studies tell us that the nutrients in our foods have been decreasing for many years now. A study I saw, from the USDA, in the 1980's showed a significant decrease in the level of nutrients in foods compared to the 1950's. I have not been able to find that study since, however.

Taste may be a fore runner of the loss of nutrients since many "conventionally" grown foods have little to no flavor anymore.. Beets purchased at the local farmers market taste very earthy and not very sweet, but beets from an organic garden will be very sweet with no earthy taste. Tomatoes from the farmers market have little flavor while tomatoes grown in an organic garden will have good tomato flavor.

Some people here will not accept this article but it does have good information in it.

https://articles.mercola.com/sites/articles/archive/2017/09/25/food-nutrients-decreases.aspx

One problem with that article is that organic produce is NOT checked for residue of the organic-approved pesticides ... just for illicit use of conventional pesticides. When is organic produce tested for residues of the pesticides "organic" growers can use? Oh, never?

Another is that the consumption was based on recall of foods eaten, not direct observation, which is well-known to be unreliable.

The third is that they were not observing a normal population, but a group of women with already diagnosed fertility problems, approaching the end of their fertile years.