In regard to the food we eat, I share the understanding first brought to our attention by Hippocrates some 2600 years ago. "One man's food is another man's poison". I address nutrition with my clients with this saying in mind, while using a system called Nutritional ID.
It is always very important to understand that we are all bio-chemically different and while one person may thrive on a particular diet; this same diet may be detrimental to another. This will be tied into our genetics as well as any functional challenges that we may be experiencing.
From a genetic factor it is important to understand that it takes our bodies many generations to create a shift for nutritional needs. Many cultures have survived with outstanding health based on the foods that were available to them on a regular basis. A traditional Eskimo survived very well in a very challenging climate with their main dietary intake being fat and protein. The Aborigines consumed much more vegetation, insects, kangaroo and wallaby yet had the strength and fitness of Olympic athletes. The Swiss consumed large amounts of high fat cheese, raw milk, small amounts of protein, whole rye and some wine yet survived very well even through glacier winters. The African Masai consumed raw milk, meat and blood from cattle yet enjoyed superb mental and physical development. I am not necessarily recommending these particular diets but hopefully this will help you understand the importance of moving toward your true genetic needs.
The functional factor ties into life’s situations such as stress, current health challenges, environment challenges and such. When we are going through challenges your body may require a nutritional shift, which needs to be addressed accordingly, until you reach a state of balance where your body can evolve to your true genetic nutritional needs.