“ We are indeed much more than we eat, but what we eat nevertheless helps us to be much more than we are.” A century ago our ancestors feared infectious and communicable diseases such as smallpox -- diseases that claimed many children’s lives and limited the average life expectancy of adults. Today far fewer infectious diseases threaten us, thanks to medical science’s ability to identify disease-causing microorganisms and develop vaccines. In developed nations, purification of water prevents the spread of infections, and immunizations protect individuals. Most people l