Is Our Food Becoming Less Nutritious?

The nutrient content of food is declining. Is it because of soil depletion, selective breeding, or... something else?
Watch my new documentary, VITAMANIA:
I came across this story as I was making the film Vitamania. When you ask sellers of vitamins why you should take vitamin supplements even if you eat a healthy diet, they will say because our food doesn't contain all the nutrients it once did. This is supposedly due to soil depletion, cold storage, food ripening off the vine, and global transport of out-of-season foods. And to an extent this is true. Foods contain the greatest amount of nutrients if they are eaten soon after they are harvested. An unexpected source of nutrient decline is the increasing amount of carbon dioxide in the atmosphere. It causes plants to grow faster and bulk up on carbs but at the expense of other nutrients, so in percentage terms the amount of nutrients are actually declining. For now this decline is modest so supplementing with vitamin pills is probably unnecessary for most people with a healthy diet but it may be a concern in future.
Thanks to Kate Pappas & Chris Kamen for writing, producing and filming this video with me
Edited by Lucy McCallum
Sound mix by Wayne Hyett
Fact Checking by Calvin Lee and Claire Smith
Thanks to the Collingwood Children’s Farm and Glenn Fitzgerald from the University of Melbourne & Agriculture Victoria
Further Reading: