The aim of my diet is to not only have a long life-span, but also a long health-span. I would rather drop dead at 90 and in the previous year be fit enough and healthy enough to move around on my own without assistance, than spend my final ten years on this earth physically or mentally unable to perform basic functions.
I have read conflicting advice from different medical practitioners both in the US and UK, so I sought out a PhD-level qualified nutrition scientist. I found someone who has a PhD from Cambridge University in cell biology and an MSc in Clinical Nutrition and had a half phone call with them. What follows is a summary of the call.