Fruits, Veggies Not as Vitamin-Rich as in Past, Says New Data

The following report of a research study by Donald Davis of University of Texas at Austin notes that foods now grown in the United States are lower in nutrients than foods grown a few decades ago. Davis attributes this to what he calls "the dilution effect" in which fruits and vegetables provide fewer vitamins and minerals as they become larger and more plentiful.  Simply put, the rapid growth doesn't allow enough time to develop nutrients.  Yet an ever increasing world population will continue to make growing foods bigger and faster a high priority.  This is why taking dietary supplements and enriching foods to ensure adequate nutrition makes sense and will continue to grow in importance.  Varying fresh foods in the diet and shopping from several different sources also helps to ensure adequate nutrition.

John W. Cartmell, MS

Fruits, Veggies Not as Vitamin-Rich as in Past, Says New Data

March 1, 2006  Fruits and veggies aren't what they used to be, new data suggests.

Of the 13 major nutrients found in fruits and vegetables, six have declined substantially, according to a study by Donald Davis, a biochemist at the University of Texas at Austin.

Using data from the U.S. Department of Agriculture, Davis concludes that recently grown crops have shown decreases of up to 38 percent in protein, calcium, vitamin C, phosphorus, iron and riboflavin when compared with produce from past decades.

What accounts for this negative trend? Like any other competitive industry, farmers' attempts to drive up profits have led them to use new techniques to increase production, Davis said. The faster-grown fruits don't have as much time to develop the nutrients.

"Farmers get paid by the weight of a crop, not by amount of nutrients," Davis said. He called this the "dilution effect": As fruits and vegetables grown in the United States become larger and more plentiful, they provide fewer vitamins and minerals.

"It's a simple inverse relationship: The higher the yield, the lower the nutrients," he said.

Davis said this happens because slower-growing crops have more time to absorb nutrients from both the sun and the soil.

"Lots of agricultural scientists don't know about this, and the public doesn't know about this," he said.

Jeff Cronin, at the Center for Science in the Public Interest, said scientists and the USDA often overlook farming practices.

"Breeding plants to improve crop yield at the expense of all other things seems to be the problem, as well as depleting soil and not rotating crops properly," he said.

While Davis is not pleased about the decreasing levels of nutrients in produce, he still encourages people to eat plenty of fruits and vegetables.

"Even though amounts of nutrients have declined, fruits and vegetables are still the richest source of protective nutrients, much better than eating highly refined foods such as white flour, sugars and fatty foods," he said.

Wheat Also Being Examined

Davis is currently researching the dilution effect in 14 varieties of wheat. His findings already suggest that, once again, the larger the yield of wheat, the lower the nutrients.

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