In this review the health relevance of vegetable bioactive compounds is discussed starting from the nutritional requirements and considering their role in the diet. All scientific evidence highlighted the importance of vegetable for human health and many of them correlated the intake of micronutrient to the reduced occurrence of degenerative diseases. For this reason, and to face the widespread obesity problem, the recommendation of five serving per day of fruit and vegetables (five a day) is perhaps the most diffused campaign of public advertisement carried out by health governmental bodies in Western countries. Different vegetables contain different bioactive compounds and this work aims to give some basic information on their chemistry. A survey on the chemical features of the main families of the vegetables bioactive compounds was given dealing with carotenoids the huge family of flavonoids and phenolic acids and finally the characteristics of glucosinolates and sulphydrilic compounds were highlighted. In a second part of this work a table was constructed reporting the indications about the occurrence of the different compounds in the vegetables. The table was commented indicating for each vegetables which are the main bioactive compounds. For each product the influence of the various biological, environmental and agricultural factors on the concentration of bioactive compounds was discussed. In particular for tomato a Index of antioxidant nutritional quality (IQUAN) was developed as a tool to guide the breeders during the program of genetic improvement to obtain cultivars with superior nutritional characteristics. Finally, the health relevance of the different vegetables was discussed considering the process variables such as cultivar, cultivation conditions and techniques, domestic cooking. The selection of cultivars having high concentration of carotenoids (e.g.: of tomato and carrot) as well high concentrations of flavonoids (e.g.: onions) is a consolidated trend. Besides, the use of agronomical practices and growing conditions is also diffuse, even though the results are significant only in few cases (e.g.: irrigation water salinity). On the other hand, the adoption of organic production protocols failed to demonstrate a significant improvement of nutritional quality in most of the cases. Post harvesting process both in the case of fresh minimally processed products and in the case of domestic and industrial thermal cooking do not impair the nutritional quality of the end products. Looking at the overall impact of process on health potential of vegetables the most important threads is the replacement of whole tissue with extracts of bioactive compounds such as those present in integrators and the various phytochemicals preparations.
Keywords: Antioxidants, glucosinolates, flavonoids, carotenoids, functional foods