I wonder if the corn that's fed to factory chickens is stripped of some high-profit components first. For large operations, that would seem likely. They might also choose a variety of corn that maximizes profit, without concern for nutritional value for the end consumer. Our food supply isn't quite as simple as it used to be.
For studies that show health benefits from certain foods, are the numbers based on the foods that the typical consumer buys, or are they based on foods specifically chosen to maximize the findings in the report? An experiment based on specifically chosen heritage broccoli grown in rich organic soil (and picked at the point of maximum quality) will probably have significantly different results than one based on typical 'grown for maximum profit' broccoli. The nutritional levels would be quite different. I forget the exact figure I last read, but I think it said that the nutritional values of present crops are down by a quarter or a third over the last few decades. So, 'an apple a day' may no longer be enough to keep the doctor away.
For studies that show health benefits from certain foods, are the numbers based on the foods that the typical consumer buys, or are they based on foods specifically chosen to maximize the findings in the report? An experiment based on specifically chosen heritage broccoli grown in rich organic soil (and picked at the point of maximum quality) will probably have significantly different results than one based on typical 'grown for maximum profit' broccoli. The nutritional levels would be quite different. I forget the exact figure I last read, but I think it said that the nutritional values of present crops are down by a quarter or a third over the last few decades. So, 'an apple a day' may no longer be enough to keep the doctor away.