What is the relationship between nutrients and disease? There are some correlations today but when we look at food as medicinal the potential for a relationship is greater than than ever. For example in today's NYT's a clear relationship between a deficiency of Vitamin D and asthma is clarified. http://well.blogs.nytimes.com/2009/02/12/new-risk-factors-linked-to-asthma-rise/
There are many other diet and health relationships with strong scientific support. A low glycemic index diet for epilepsy. There is much information about the effecacy of this and glycemic indexes are readily available online. http://diabetes.webmd.com/glycemic-index-good-versus-bad-carbs.
Fish oils and flaxseed oil supplements have strong support from the scientific community.
The evidence for the medicinal benefits of berries got Tara Parker-Pope's attention and made the NYT. http://well.blogs.nytimes.com/2009/01/22/the-power-of-berries/
Parker-Pope also describes how eating the Mediterranean diet appears to lower risk for mental decline according to research published in Archives for Neurology. http://well.blogs.nytimes.com/2009/02/10/mediterranean-diet-may-prevent-mental-decline/
Yet though we know so much, as well as that 30% of American adults are overweight or obese with only 1 of 50 states boasting a lower rate, still insurance companies pay very little for preventative care and health education. Roni Caryn Rabin, of the NYT, reports on a survey that found health scares reduce smoking but not weight. Rabin quotes Sherry Pagoto, an assistant professor at the University of Massachusetts Medical School, who co-wrote an editorial accompanying the paper. Pagoto believes physician counceling does not have much impact and “The evidence for behavioral weight loss treatment suggests an intensive program is necessary."
Oddly, there is little money for prevention but this might end as we change our priorities in America.