Enhancing Intake of Dietary Nutrients From Vegetables and Fruits: How Are We Doing?

Vegetables and fruits are major sources of micronutrients and phytonutrients, as well as several minerals. Crop domestication and modern breeding have, for some crops, resulted in dramatic changes in nutrient content. Modern examples include projects to improve the protein, fat, carbohydrate, vitamin and mineral nutritional quality of staple crops, and genetic improvement of micronutrient and phytonutrient levels in several vegetable crops. Genetic analysis of numerous micronutrients and phytonutrients in many vegetable and fruit crops sets the stage for future nutritional improvement.  The need to improve horticultural crop nutritional value and intake is urgent. Diet is implicated globally in the cause and severity of many diseases, including cancer, heart disease, and diabetes, and consumption of healthier foods has the potential to alleviate both the incidence and severity of these diseases, as well as obesity, which is a causal factor for many chronic diseases. The Dietary Guidelines Advisory Committee identified inadequate intake for three minerals (Ca, Mg, and K), two vitamins (A and C), and fiber for at least half of the U.S. population, and horticultural crops are major sources of several of these nutrients.  Increased consumption of healthier foods not only improves human health, but also has positive economic benefits to U.S. agriculture. A USDA–ERS report indicated that consumer adoption of the recommendations of the 2005 Dietary Guidelines for Americans would significantly alter food demand and production with positive economic impact. In spite of these needs, efforts to improve crop nutritional value have not been widely embraced by plant breeders. A primary reason for this lack of effort in improving crop nutritional value is the lack of added economic value to be realized from such an effort. Other factors contributing to the minimal effort in improving crop nutritional values are expensive methodologies to quantify nutrients, difficulties in maintaining product identity and labeling for growers and marketers, and lack of obvious immediate value to consumers. While horticultural crops are key dietary sources of several shortfall nutrients, one study indicates that the nutrient content of most U.S. vegetables has, in fact, declined since 1950. The good news is that broad genetic variation for increasing crop nutrient content exists for most nutrients in most vegetable and fruit crops. An evaluation of past recent history of vegetable and fruit crop improvement will be discussed, and prospects for future efforts to enhance horticultural crop nutrient content and intake will be presented.