Doubling our remaining life expectancy is attractive for some of us with long-term goals. It is difficult even to speculate on what a gain of 30 years in life expectancy might mean, these days. I personally am rather curious to see the spinoffs from the human genome project. It was thought by most researchers that this possibility had been ruled out, but a careful look at the literature shows that this may not be so. There are theoretical reasons to suppose that both PR and CR contribute to the effect of food restriction.
More work needs to be done.
There's little evidence that this occurs when CR is instituted in adulthood. The USDA's nutrient database is publicly available at info.umd.edu. A few people on the Net have written software to read the data. Recently, flaws in the data have come to light, but the data set is probably fairly reliable, on the whole. There are a few commercial nutrition analysis programs available that have far more complete, reliable data.