A central issue that must be addressed by phytonutrient research is how to
assess the effects of phytonutrients on long-term health. Proper assessment
of these effects requires the measurement of biomarkers of long-term healt
h in people consuming any particular phytonutrient. This is a brief review
of what is known about biomarkers of cancer risk, immune function, and agin
g. Relatively few biomarkers of long-term health have been even partially v
alidated in experimental animals or people.