Excerpts from an Organic Center report:
High yields and jumbo produce deliver more water, starch, and sugar per serving, but less vitamins, minerals and antioxidants.
Farmers have doubled or tripled the yield of most major grains, fruits and vegetables over the last 50 years. But American agriculture’s single-minded focus on increasing yields over the last half-century created a blind spot where incremental erosion in the nutritional quality of our food has occurred. This erosion, modest in some crops but significant in others for some nutrients, has gone largely unnoticed by scientists, farmers, government and consumers.
Government data from both America and the United Kingdom have shown that the concentration of a range of essential nutrients in the food supply has declined in the last few decades, with double digit percentage declines of iron, zinc, calcium, selenium and other essential nutrients across a wide range of common foods. As a consequence, the same-size serving of sweet corn or potatoes, or a slice of whole wheat bread, delivers less iron, zinc and calcium.
Fewer nutrients per serving translate into less nutrition per calorie consumed…that is, we have more food, but it’s worth less in terms of nutritional value.
Substantial data show that in corn, wheat and soybeans, the higher the yield, the lower the protein and oil content. The higher tomato yields (in terms of harvest weight), the lower the concentration of vitamin C, levels of lycopene (the key antioxidant that makes tomatoes red), and beta-carotene (a vitamin A precursor). High-production dairy cows produce milk that is less concentrated with fat, protein and other nutrition-enhancing components, and are also more vulnerable to a range of metabolic diseases, infections and reproductive problems.
“To get our recommended daily allowance of nutrients, we have to eat many more slices of bread today than people had to eat in the past,” says Brian Halweil, a senior researcher at the WorldWatch Institute and the “Still No Free Lunch” author.