Dr Clayton stakes out his beliefs in the opening paragraphs:
"You are unlikely to die of old age. Because very few people do perhaps 1 in 10,000!
"Yet cell culture studies, and the few individuals who live on healthily into their second century, indicate that our true lifespan probably lies between 110 and 120."
So why is a long and healthy life such a rarity? Why do so few of us live out our biological potential?
The major causes of ill health and death now are the chronic degenerative diseases such as: Heart disease, Stroke, Cancer, Diabetes, Osteoporosis and Alzheimer's.
Yet, as Dr Clayton points out, some people do achieve active and healthy old age, and there are whole populations where the incidence of these diseases is a fraction of our own in the West.
So he has analysed their diets to identify the most protective nutrients from these, the world's healthiest diets. Incorporating these foods and nutrients into your diet offers the best chance of cutting the risk of the main degenerative diseases and thereby achieving not simply a longer life, but a longer quality of life.