Optimal nutrition: fibre and phytochemicals

There is currently intense research interest in secondary plant metabolites because of their potential preventative effects on the chronic diseases of Western societies, especially cardiovascular disease and cancer. To date m ost of the research has focused on the identification of plant-derived subs tances and their potential protective effects against specific chronic dise ases. The important issue of determining the optimal intake of those substa nces, such that the beneficial effects are maximized without manifestation of adverse effects, has yet to be addressed in most cases. Furthermore, the re are no specific functional markers that can be used to assess optimal in take, although it may be possible to use biomarkers such as serum cholester ol if the rest of the diet is strictly controlled. The present review discu sses a wide range of substances associated with plants, including dietary f ibre, resistant starch, oligosaccharides, phyto-oestrogens, phytosterols, f lavonoids, terpenes and isothiocyanates, and attempts where possible to ind icate optimal intakes and to suggest functional markers.