Our foods lose essential nutrients at every step of the process from their growth to our dining tables. It starts with the nutrient-depleted soils in which the crops are grown, then the loss accelerates during food shipping, processing, storage, and finally cooking.
Nutrition scientist Shari Lieberman, co-author of The Real Vitamin & Mineral Book, cautions that “even if we ate a ‘balanced’ diet, our food has less nutrition to begin with because it is raised using synthetic chemicals, and then it is stored and processed to within an inch of its life. The flour used to make white bread has been depleted of over twenty nutrients, including up to 40 percent of vitamin C, 85 percent of vitamin B6, and 72 percent of zinc. The manufacturers then put back a handful of these nutrients (five, to be exact) and call the result ‘enriched.’”
Because vitamin E causes food to turn rancid sooner, food processors remove it to extend the shelf life of food products. With wheat grain, about 86 percent of vitamin E is lost anyway during milling and processing into white bread. One theory holds that heart disease went from a few reported cases in the early twentieth century to being a major killer at the end of that century as a consequence of vitamin E being stripped from our food.
Fitzgerald, Randall. The Hundred-Year Lie: How to Protect Yourself from the Chemicals That Are Destroying Your Health (p. 135). Plume. Kindle Edition.