To presume to tell anyone what the composition of a "proper" diet should be is like stepping into shark infested waters. There is no general agreement even among experts in the field.

Controlled studies using various experimental diets cannot be done because large groups of people would have to be followed for 10, 20 or even 50 years before meaningful data could be collected. Who would want to subject themselves to such a study to say nothing of what it would take to enforce the diet in childhood.

Therefore we are faced with innumerable diet theories. Many of the theories are motivated by various marketing incentives which are not necessarily in the best interest of the individual wishing to undertake the diet.

What is one to do?
To start with I think it is helpful to think about what our ancestors ate. Not ancestors of 500 to 1,000 years ago but ancestors of one million to ten million years ago. It is from them that we inherited the traits which require that unknown mix of foods to achieve maximum health. Unfortunately we do not know exactly who all of our ancestors were or what they ate. We can assume there was plentiful vegetation and that they ate large quantities of leafy greens, fruits, and nuts.

There was also meat in the diet of most of our ancestors. Then animals were not raised in feedlots and the fat content of the meat eaten was extremely low. The composition of the fat in those animals was heavily influenced by their intake of natural vegetation which was high in omega-3 fatty acids. (Read more about Fat)

Today animals destined for our ovens and barbecues are raised on grain and corn and lack the types of nutrients and essential fats present in natural vegetation. Farm raised fish also are fed a deficient diet compared to wild fish.

Farming did not start until about 13,000 years ago. A very short interval in the history of man and probably not long enough to influence our genetic characteristics substantially. Prior to that time the intake of abundant sugars, rice, cereal, potatoes, and bread was virtually non-existent.

The change in our dietary habits in the last 13,000 years accounts for some of the major causes of death in our society today. Humans found to be living in primitive circumstances in the past 100 years have been found to be largely free of cardiovascular disease and cancer. Their diets have come from completely natural sources. A diet followed by primitive people is unlikely to appeal to our society.

Cardiovascular diseases account for the largest total number of deaths in the USA. They cause more deaths than the next four most common causes combined, including cancers. This is not true for people who eat the so-called "Mediterranean, Asian, Latin, and Vegetarian" diets. These diets have been in existence for over one thousand years with a low incidence of cardiovascular disease and cancer.