USDA figures that show a decline in mineral and vitamin content of several fruits and vegetables between 1914, 1963, and 1992.
Table 1 is a summary of mineral decreases in fruits and vegetables over a 30-year period, adapted from Bergners book.
|Table 1. Average changes in the mineral content of some fruits and vegetables, 1963-1992|
|Mineral||Average % Change|
Fruits and vegetables measured: oranges, apples, bananas, carrots, potatoes, corn, tomatoes, celery, romaine lettuce, broccoli, iceberg lettuce, collard greens, and chard.
In England, Anne Marie-Mayer compared food composition over a 50-year period using data from the UK Ministry of Agriculture, Fisheries and Food (MAFF).
Her study (21), Historical Changes in the Mineral Content of Fruits and Vegetables was presented at the Agricultural Production and Nutrition conference held at Tufts University School of Nutrition Science and Policy on March 19-21, 1997.
Table 2, adapted from Marie-Mayers paper, summarizes the average ratio of nutrient content and dry matter of 20 vegetables and 20 fruits.
A ratio of 0.81 for Ca, for example, means that over an approximately 50-year period the average content of calcium in vegetables has declined to 81% of the original level.
|Table 2. Average ratio of mineral content and dry matter for vegetables and 20 fruits|
Minerals are basic elements of the earth. They cannot be created or destroyed. Once eaten, they are gone forever from the soil.
While a plant can create proteins, carbohydrates and many other nutrients, it cannot create minerals. They are either in the soil or they are not.
Many soils have produced food for years. The minerals in those foods were eaten long ago.
By 2020, meeting the energy demand of an expanding population will require that farmers
produce one and a half times as much food as they did in the early 1990s.
By 2050, the worlds' agricultural systems will need to generate enough food to support the nutrient requirements of over 8.9 billion people (United Nations, 1998).
This will require that agriculture, match its earlier success in increasing food production. This must all be accomplished with about the same land under cultivation but with dwindling water resources and declining soil fertility.(Brown and Flavin, 1999; Pinstrup-Andersen, 1999).