Imagine a diet plan that saw through to the core of your being and beyond, that took into account not just the foibles and little secrets no one else knows about (it's awfully easy to dispose of incriminating Wendy's bags and 3 Musketeers wrappers) but even the secrets that you don't know -- secrets that can help keep you alive longer and in better health.

This is the promise -- and the threat -- of the latest scheme for dramatic health improvement to fall out from the big bang of the Human Genome Project. Nutritional genomics -- or nutritional genetics, or nutrigenomics -- examines your diet and your genes to determine how they interact. Proponents argue that nutrients in food alter gene expression or structure, acting differently on different people according to their genetic makeup. Once these interactions are understood, the story goes, people can make up for inherited weaknesses or genetic flaws by eating differently and, when necessary, taking dietary supplements. Understanding the links between genes, specific nutrients, and a range of diseases -- from diabetes and heart disease to less obvious diseases like some cancers and neurodegenerative syndromes -- will result in a diet plan tailored to your very own gene profile.