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Title: Assessing nutritional changes in a vegetable over time: issues and considerations

item Farnham, Mark
item Grusak, Michael

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2013
Publication Date: 2/1/2014
Citation: Farnham, M.W., Grusak, M.A. 2014. Assessing nutritional changes in a vegetable over time: issues and considerations. HortScience. 49:128-132.

Interpretive Summary: Throughout the 20th Century, there were concerted efforts in nearly all agronomic and vegetable crops to improve cultivated varieties for many different traits including crop yield, crop quality, disease resistance, and numerous other characters. Little is known about changes that may have occurred in the concentrations of various nutrients, and whether such changes might be associated with the selection for other traits. USDA scientists at the U.S. Vegetable Laboratory in Charleston, South Carolina, and the Children’s’ Nutrition Research Center in Houston, Texas, reviewed what is currently known about possible changes in nutritional concentrations of our food crops with a particular focus on vegetable crops. These scientists showed that any evidence indicating changes in nutrient concentrations, and specifically mineral concentrations, for most vegetables is circumstantial at best. They also presented the necessary issues that must be addressed in carrying out systematic field studies aimed at testing for possible changes that might be associated with the introduction of new varieties over time. They emphasized that the set of crop varieties to be tested and the way that nutrient levels will be expressed is particularly important, but they also showed that a crop’s evolution and the history of consumption of the vegetable in question must be considered when looking at the impacts of possible changes. This review provides useful information to plant scientists working to maintain or improve nutritional content when breeding for other traits, and also informs nutritionists interested in better understanding the nutritional qualities of vegetables.

Technical Abstract: For many decades plant breeders have worked to improve vegetable crops for numerous economically important traits, like host plant resistance to disease, yield, and vegetable quality. Most improvements have been made with little knowledge as to how, or if, nutritional or phytonutrient concentrations might also be indirectly altered in the process. There have been some reports suggesting that concentrations of nutrients in vegetables have been reduced over time, possibly related to introductions of new cultivars. However, for most vegetables, current evidence indicating changes in nutrient concentrations, and specifically mineral concentrations, is circumstantial at best. To effectively test whether or not changes may have occurred over time as new cultivars replace older ones, appropriate field studies must be conducted wherein harvested produce from “old” versus “new” crop cultivars are analyzed by appropriate methods and compared directly. Numerous considerations and issues such as: 1) the set of cultivars to be used in field tests; 2) how nutritional concentration will be expressed; and 3) the evolution, history, and consumption changes of the crop under study; must be addressed in making such direct comparisons and interpreting results.