The PURE study is one of the largest epidemiological studies in recent memory, and its findings seriously question the dietary guidelines around fat, carbohydrates and salt. In fact, the PURE study suggests that higher fat intake reduced mortality, that lower salt intake increases mortality, and it even shows us how LDL is a poor predictor of health outcomes. As an epidemiology study, how much faith can we place in the results, and how do these results fit into to our current knowledge base? Professor Mente helps us make sense of these questions and more.