Declining Fruit and Vegetable Nutrient Composition: What Is the Evidence? -- Davis 44 (1): 15 -- HortScience: "Declining Fruit and Vegetable Nutrient Composition: What Is the Evidence?
Donald R. Davis1,2,3
Biochemical Institute, The University of Texas, Austin, TX 78712; and Bio-Communications Research Institute, 3100 North Hillside Avenue, Wichita, KS 67219
Three kinds of evidence point toward declines of some nutrients in fruits and vegetables available in the United States and the United Kingdom: 1) early studies of fertilization found inverse relationships between crop yield and mineral concentrations—the widely cited 'dilution effect'; 2) three recent studies of historical food composition data found apparent median declines of 5% to 40% or more in some minerals in groups of vegetables and perhaps fruits; one study also evaluated vitamins and protein with similar results; and 3) recent side-by-side plantings of low- and high-yield cultivars of broccoli and grains found consistently negative correlations between yield and concentrations of minerals and protein, a newly recognized genetic dilution effect. Studies of historical food composition data are inherently limited, but the other methods can focus on single crops of any kind,"