This week (among other things, including my Vespa breaking down twice in three days) I was busy taking part in an interview panel for a research associate position, together with colleagues in the Medical School at UCL.
One of the questions we were asking to the candidates was about commenting a new study (incidentally, by researchers at UCL) which using data from the Health Survey for England argued that the current "optimal" regime of consuming 5 portions of vegetables and fruit per day could (should) be in fact increased to at least 7, to reduce risk of death.
The point of the question was of course to get the candidates to recognise the possibility of confounding $-$ of course people consuming more veg & fruit might have a much lower risk of death to start with, due to different life-style, etc. (A few candidates got it right straight away, others less so).
But I think this has even more interestingly (eg, economic) implications in terms of the actual applicability of the health policy, in its current form as well as in terms of potential modifications, like this article in today's Guardian (which I thought was spot-on!) suggests.