Bioactive Nutrients in Vegetables for Human Nutrition and Health

Abstract

Vegetables are parts of plants that are consumed by humans as food. They can be eaten either raw or cooked and play an important role in human nutrition, being mostly low in calorie, fat and carbohydrates, but high in vitamins, minerals and dietary fibre and particularly antioxidant vitamins A, C and E. There is an increasing awareness about the advantages of diet rich in vegetables to ensure an adequate intake of vitamins, micronutrients, dietary fibres and antioxidant phytochemicals, and it has been demonstrated that there is reduction in the incidence of lifestyle diseases including cancer, stroke, cardiovascular disease and other chronic ailments with inclusion of vegetables. Phytochemicals (phyto means plant in Greek), also referred to as phytonutrients, are thought to be largely responsible for the protective health benefits of these vegetable-based foods. The phytochemicals, which are part of a large and varied group of chemical compounds, are classified according to their chemical structures, and functional properties are also responsible for the colour, flavour and odour of vegetables, such as broccoli’s bitter taste and garlic’s pungent odour. Tens of thousands of phytochemicals have been identified, of which flavonoids are the largest, most varied and most studied group of phytochemicals. In fact, more than 6000 flavonoids that occur in plant foods have been described. Research on specific phytochemicals in vegetables and their effects on disease risk is limited; however, studies strongly suggest that consuming foods rich in phytochemicals provides health benefits. Still, it is not known whether the health benefits are the result of individual phytochemicals or interaction of various phytochemicals, and also not enough information exists to make specific recommendations for phytochemical intake. More interdisciplinary work is required that involves nutritional and food scientists as well as others from the biomedical field to ascertain the true function of specific phytochemicals.