The Future of Breeding Fruit and Vegetables with Human Health Functionality: Realities, Challenges, and Opportunities

While recognition and awareness of potentially health functional compounds in fruits and vegetables has increased the past 15 years, much remains to be learned concerning the long-term value of phytochemicals in the context of a complex modern human diet. Some consumers express concern that evidence of efficacy for particular foods or ingredients appears, only to be contradicted soon thereafter by further studies. Others seek highly reductive approaches to health functionality based on information from complex mixtures of plant-based extracts. Still others focus attention on whole, raw, or minimally-processed foods. Great expectations have been built for fruits and vegetables, but few clear outcomes have been realized. Despite our lack of understanding, and often without substantial preliminary data, many plant breeders and biotechnologists have made efforts to enhance the concentration or quality of suspected health-promoting substances in crops, and some surprising and potentially valuable modifications have been effected. Traditional breeding, marker-facilitated selection, transformation, chromosome manipulations, and the creation of new mutant alleles have been employed in these strategies and provided variable outcomes. But these efforts have also underscored a number of important concerns underlying the challenges to improving vegetable health functionality. These include: unknown bioavailability of the target compounds; biosynthesis of target compounds in species or plant organs where these compounds are non-native; challenges with over-expression of transgenes; modification of antinutritional factors or defensive compounds that serve other purposes in the plant; consumer preferences for processed foods; declining consumer interest in cooking whole foods; reductions in fruit and vegetable consumption among U.S. consumers; and the extent of genetic variability for metabolism of plant-based compounds in humans. While selection in plant breeding programs is certainly effective in modifying crop plants for phytochemical content, it is no guarantee of improved human health outcomes. Future progress will be partly tied to our ability to work in an interdisciplinary fashion with nutritional and food scientists, and those in biomedical fields, to ascertain if true and clinically-relevant health functionalities can be obtained from plant-based compounds. It is hoped that such efforts will clarify issues of bioavailability, dosage, frequency, the effects of cooking and processing, and genetic differences among eaters. Perhaps more importantly however, future progress with respect to human health will be associated with the consumer’s interest in fruit and vegetable consumption for its own sake, as a lifestyle and a practice, rather than as a solution to medical problems.