I think that's being a bit ungenerous to longitudinal studies! It's not quite as simple as PP's analogy! And most scientists (and people conduction research on human nurition) are aware that correlation does not equal causation. But that never gets past the sub-editors on the national papers.

I think the benefits of fruit/veg in the diet are several and none have anything to do with antioxidants (so unanimity in the lanciatore/tovaglia household there!) -

1) vitamins that are not available from animal sources eg vitamins E & K
2) provides fibre which is beneficial for several reasons
3) v low in fat (if any at all) and it's unsaturated

anyway at least JOLF gives you a thorough checking over. I just get a lung function test once per year.