As far as I'm aware, there are less than five studies -- total -- which have been carried out on a reasonably representative sample of the population (i.e. not

As far as I'm aware, there are less than five studies -- total -- which have been carried out on a reasonably representative sample of the population (i.e. not military service-members), which studied diet patterns, and which lasted strictly longer than two years. Most people live much longer than two years, so this would seem to be a systemic weakness. But people lived before peer-reviewed research. They collected information somehow and used it somehow and it worked to varying degrees of success, which has been reflected in the rise and fall of various societies and in the quality of life in those societies. The challenge is not to abandon peer-reviewed research, but to integrate it effectively with other sources of knowledge.