Why eat less fat and more fresh fruit and vegetable?

Prof Halliwell said: ‘At the moment, all that we can conclusively say is that the populations of advanced countries would benefit from eating less fat and more fresh fruit and vegetables and perhaps taking multivitamin or mineral supplements.’

See http://hl123.blogspot.com/2011/04/hope-in-humble-worm-article-by-chang-ai.html.