Some of my favorite ways to study the effects of diets and lifestyles on health is to take an objective look at the healthiest cultures on the planet. Although these studies are observational, they study real people living in a real environment. They provide us with invaluable information about how health and longevity are affected by the culture in which we live. Granted, your diet is only part of the total equation. And it must be emphasized that these healthy patterns are based on traditional habits of these cultures. When Western-type diets invade these populations, time and time again, their positive health statistics change generally for the worst. Please watch the video and then go out and buy some sweet potatoes.