Organic Farms Ames IA

Scientists link food pyramid changes to declining nutrients in fresh produce.

Since the birth of agriculture, farmers have typically measured their farming success by the size of their crops. Many methods can increase crop yields like irrigation, fertilization, chemical weed and pest control and cultivated breeding. Significantly increasing yields of wheat, rice and maize, resulted in the “Green Revolution” of the sixties and seventies. Unfortunately, we have learned that increased yields may reduce concentrations of some nutrients. There can be trade-offs between yield and nutrient concentration. This is known as the “dilution effect.” In the dilution effect, yield-enhanc­ing methods like fertilization and irrigation may decrease nutrient concentrations as a result of environmental dilution. In plain English, when plants are made to grow bigger and faster, they are not able to draw as many nutrients from the sun or soil. Essentially, crops that grow larger and faster are not able to absorb nutrients at that same rate from the soil or by photosynthesis.

Organic farm advocates have always maintained that conventionally grown produce is not as tasty or nutritious as organic fruits and vegetables. Now a scientific study shows that the nutritional content of conventionally grown fruits and vegetables has dropped markedly since the 1950s. In early 2006, Dr. Don Davis of the University of Texas delivered his paper to the American Association for the Advancement of Science on the subject of declining nutritional value of conventionally farmed produce. In the scholarly article titled, A Perspective on Nutrient Decline, Davis detailed and explained the factors contributing to the decline in nutrient concentrations in common fruit and vegetable crops over the last five decades. He compared historic and current U.S. Department of Agriculture data on 43 garden crops including vegetables, strawberries and melons and found that the modern produce had lost protein, down an average of 6%, calcium down 16%, vitamin C down 20%, riboflavin down 38% and phosphorus down 9%. The study was published in Food Technology magazine in 2005.

From all outward appearances, this scientific evidence of nutritional decline in our food barely caused a current; one Scripps Howard science writer filed a story on it while the rest of the press ignored it. It is even more shocking to learn that since 1981, the Department of Agriculture has maintained data showing extreme nutritional content decline in fruits and vegetables. According to the data, half the major nutrients tracked by the Department from 1950 to 1999 showed significant declines. Evidently the primary cause is selecting and growing crops for quick maturity, which means they don't have time to absorb and metabolize nutrients.

In fact, the 2006 revised USDA food pyramid nearly triples the daily servings of fruits and vegetables. Does that mean that the fresh produce we’re eating is not as nutritious as it once was...