There is a post on Alan Aragon's blog which should be required reading for everyone. The post itself concerns Dr Robert Lustig's recent video on the dangers of fructose in the modern diet. Aragon makes a convincing stab at taking much of what Lustig says apart.
Where things really get interesting is in the comments section where Lustig himself turns up to defend his position. Subsequently the usual themes and defenses are offered up by assorted contributors with varying degrees of success.
The thread highlights how confusing and conflicting nutritional advice is. It also highlights the problems of a guru based approach to diet and training.
For me, I know that the 'paleo' approach is simple and gets me most of the way there. But that does not mean there isn't another approach that could deliver the same results or better. What I do may not be optimal but I find it an easy approach to health and fitness. I tweak stuff and experiment. 'Paleo' has given me a good starting position but it does not provide all the answers.
Aragon's post is a good reminder that we should not ignore research that tackles cherished beliefs.