We are encountering a significant progress in nutritional knowledge, releva
nt to the practice of all aspects of human nutrition, medicine and public h
ealth. So, it is conceivable that we may view the role of nutrition differe
ntly in the future. The diet may not only provide an adequate amount of nut
rients to meet the metabolic requirements, but could also contribute to imp
roving human health status. As a consequence, extracts of plants or single
compounds thereof which are believed to benefit human health need to be ide
ntified and developed for the food market to complement a balanced diet. Th
e assessment of risk and benefit of constituents of a diet or plants will b
e a challenge for scientists working in this area. The number of compounds
to be tested is enormous. Their impact on human health is supposed to be th
rough prevention. Their effect on the human system may be modest, yet still
significant when consumed over an entire lifespan. Trials employing tradit
ional clinical endpoints, for many reasons, appear not to be feasible to in
vestigate the relevance of these compounds on human health. Rather biomarke
rs, which are 'surrogate endpoints' for clinical events, may be used in the
field of nutritional science. These biomarkers have to be highly sensitive
and specific, non- or minimally invasive and inexpensive and they need to
be validated and standardized. The biomarker concept may prove essential in
nutritional science to demonstrate the effect of diet constituents on huma
n health.