Plant Nutrient Density: The Forgotten Trait

“A purple potato native to Peru has 28 times more cancer-fighting anthocyanins than common russet potatoes,” writes Jo Robinson, author of the book Eating on the Wild Side: The Missing Link to Optimum Health. “One species of apple has a staggering 100 times more phytonutrients than the Golden Delicious displayed in our supermarkets.”

Researchers have been tracking the falling nutrient levels in fruits, vegetables and grains for decades, but recent scientific advances have made the comparisons more precise. As Robinson notes, “These insights have been made possible by new technology that has allowed researchers to compare the phytonutrient content of wild plants with the produce in our supermarkets.”

These vital phytonutrients are “compounds with the potential to reduce the risk of four of our modern scourges: cancer, cardiovascular disease, diabetes and dementia.”

Along with the usual suspects — companies that breed plants for size, convenience and overall profitability, as well as create new GMO varieties that are designed primarily to survive a lifetime of dousings with patented pesticides — the consumer’s preference for sweeter versions of old favorites has also played a role.

Corn is a prime example. The author tells the story of how rich indigenous corn was replaced over many generations by the much sweeter corn of the modern supermarket. When colonists first arrived in North America, a native variety of corn covered the land, sustaining communities and cultures. 

In his book A New Voyage to Carolina, published in 1709, English explorer John Lawson wrote: “The Indian Corn, or Maiz, proves the most useful Grain in the World; and had it not been for the Fruitfulness of this Species, it would have proved very difficult to have settled some of the Plantations in America.”

The corn wasn’t simply yellow, but came in a kaleidoscope of hues. John Winthrop Jr., a 17th-century governor of the colony of Connecticut, observed that this indigenous corn was “red, yellow, blue, olive colour, and greenish, [with] some very black and some of intermediate degrees.”

These colours were nature’s way of signaling nutrient density. Indian corn was rich in anthocyanins, which scientists believe play a role in fighting cancer, reducing inflammation, decreasing cholesterol and blood pressure, protecting the aging brain, and lowering the risk of obesity, diabetes and cardiovascular disease.

These original varieties are now hard to find. The corn most commonly sold in stores in Canada and the U.S. is the result of controlled laboratory mutations that added high levels of sugar to the corn.

“Today, most of the fresh corn in our supermarkets is extra-sweet,” Robinson notes. “The kernels are either white, pale yellow, or a combination of the two. The sweetest varieties approach 40 percent sugar, bringing new meaning to the words ‘candy corn.’”

In the search for sweetness, survivability and plump retail margins, nutrition is often the forgotten trait. In fact, when new kinds of fruits and vegetables are bred, the focus is on creating varieties that will be resistant to weeds, insects and disease. The concept of breeding for nutritional value seems disconnected from the marketplace forces that govern the mass production of produce.

Significantly, Robinson reports that she has interviewed plant breeders “who have spent a decade or more developing a new variety of pear or carrot without once measuring its nutritional content.”