Any truth to these claims? I remember reading somewhere years ago that these types of claims aren’t true, but a Google search lead me nowhere.
Some of the material here might be of interest to you.
It is not completely untrue. One primary requirement for mass farmed vegetables is that they are stable under shipping conditions that may be thousands of miles. Given any particular vegetable, it is unlikely that the variety that is the best tasting and most nutricious happens to be the type that ships easilly. Tomatoes are a good example of that. Take a look at some seed catalogs some time. There is a bigger variety of vegetables you can grow yourself than there ever were but you won’t find most of them in any store because they can’t survive adverse consitions well or they spoil too quickly.
Are some parts untrue?
You can grow nutritious vegetables just like you always could and there are places including farmers markets that sell great produce. The untrue part would be assuming that nutritious produce simply isn’t available anymore.
The ones this guy compared, had less nutrients acording to him. Sample some other produce and you will find a variance. A large sample over time checked the same way is needed over years to mean anything. I see no mention of the method used to measure nutrition. I will bet he didn’t use the same methods as the original studies either. There are going to be large differences between sources of produce. Were the original gathered from a field and checked immediately, while this guy checked ones that were setting for days? Some newer varieties have been breed for high vitamin content, than it’s predecessors. That last link seemed to be about giving a guy money, and errors in records.
Where do the nutrients go when the produce sits in a truck or on a shelf for a long period of time? Do they break down?
Yes
It should probably be noted that the development of varieties that ship well tends to mean that fresh veggies are now more widely available and relatively cheaper, which can be seen as offsetting a decline in per-veggie nutrition
The next question is does it matter if they have less usable nutrition, because the persons that eat it, still eat more than the body can use?
Vegetables and fruits are also now bred for size and rapid growth over nutrition and flavour because that’s what is economical.