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? Chief scientist Charles Benbrook of The Organic Center says the food pyramid revision is directly related to the decline in the nutritional content of fresh food.
“We’ve developed farming systems that grow a lot of plant matter and creates a lot of mass, whether that’s starch or fiber or pulp. However, we haven’t developed equally effective technology methods to enhance the fertility of the soil. So all the essential micronutrients in the soil that are needed for the plant to manufacture the vitamins and antioxidants that make food really good for you, that capacity has not kept up. That’s why we are now seeing these declines in the protein content of food, protein quality and in the vitamin, mineral and antioxidant levels.” Benbrook said.
In brief, Benbrook explained that plants produce a wide range of plant secondary metabolites, chemicals that the plant naturally synthesizes to help it cope with potential dangers or stresses in its environment. The stresses might be completely climate driven. For example, antioxidants are produced by plants to deal with sun burn. If it’s too hot or sunny, plants produce antioxidants as a sort of natural sunscreen. Plants produce antioxidants to deal with insects that attack, chew or suck on the tissues of the plant. The antioxidants produced by them try to seal off and stop the spread of viruses that start or grow on the plant. These are all produced in response to biotic or ambiotic stress. Biotic stresses are those caused by another organism. Ambiotic stresses are those caused by the environment in which the plant lives. These reactions are what make the food more nutritious to humans.
Benbrook says that the population will get the most benefit out of produce if they are able to purchase certified organic fruits and vegetables with high levels of minerals and antioxidants. Regarding the food pyramid, Benbrook said, “We’re kind of going one step forward and two steps back if we get the American public to increase its consumption by 20% but the nutritional content has gone down 30%. We want to reverse that. We want to bring back the higher level of vitamins, minerals and antioxidants in fresh produce that was common in the 50s’ and 60s’. And we think that through modern and sophisticated farming systems we’re going be able to do that.”
Benbrook believes much can be done to make the soil more nutritious for growing produce. “Farmers have to find ways to diversify the macro-organisms in the soil and create environments in the soil where the numbers of the raw biomass increases. That’s the key,” Benbrook said. “It’s the life in the soil that releases the hidden treasures of the soil fertility, if you will. The raw life in the soil makes the plants essential nutrients available.”
Benbrook explained how conventional verses organic farming deals with soil fertility. “That’s the big problem for and the worst part of conventional agriculture, farmers believe that soil fertility is about what you buy in a truck that they come and spray on your field. It isn’t about caring for, managing and feeding the soil. And that’s really the difference, philosophically and as a practical matter, between an organic farmer and a conventional farmer,” Benbrook said, “The organic farmer believes that the way to grow healthy plants is to have healthy soil. They focus a lot of their attention on managing the soil environment so that it’s conducive to great diversity and healthy populations of soil micro-organisms. The conventional farmer doesn’t think that much of the microbiological properties of the soil and in fact does many things to damage that environment. You can’t buy all aspects of a truly fertile soil in a fertilizer bag.”
Regarding the seeming lack of interest in this information among the general public, Benbrook racks it up to dollars and cents. “Declining nutritional quality is a big issue right now but also one that people don’t want to talk about especially in the general public. U.S. corn and soy bean export sales are going down because they’ve dropped in their protein levels as compared to corn and soy beans grown elsewhere in the world that have richer soil environments.”
Benbrook concedes that the transition from conventional to organic farming is both technically challenging and expensive. But a way to start is for farmers to diversify the crop rotations or cropping patterns that they are growing. “Start to return to the soil, organic elements that will begin feeding the microorganisms and enriching the soil.” Benbrook said.
Overall Benbrook sees the big picture of nutritional decline. “Such a big problem boils down to the structure of agriculture. One; we don’t have enough farmers out on the land. Two, the average farmer today doesn’t have the time to work with the soil and improve it while making a living at the same time. Farmers don’t make enough from what they sell their crops for to do a really good job. It’s hard to expect farmers that are just scraping by using conventional methods to make that change. A lot of them who would really like to do it just don’t have the means available to them. There are all sorts of practices that farmers can build into their business as they go. That’s the only way big change can happen, by many, many little changes.”
Also, check out this informative blog entitled No Nutritional Difference Between Conventional and Organic Foods? The Organic Center to the Rescue!