The pyramid of power it is a graphical representation many public bodies have been used throughout history to indicate to the population that must consume on a daily basis in function of the nutritional recommendations of the time.
As is logical, the pyramids of food have been updated based on the knowledge that science has acquired over time on dietary and nutrition.
Although it has not always been so. In many cases, the reviews of the pyramids have been influenced simply economic or political interests without any backing of scientific evidence.
For example, if there was a shortage of food or its price went up, also went up casually to their position in the pyramid. Without more, this is what happened in Sweden in the 70's, when the meat, fish, and eggs climbed to the first level of the pyramid and cheaper food (bread, cereals, potatoes,...) is left in the base.
Another famous example is the food pyramid that the Department of Agriculture of the united States created in the early 90's and many other taken as reference.
Knowing who the author is, it is not strange to see at the base of the pyramid cereals, bread, pasta and ricejust all products from the agricultural crops the american government subvencionaba. How would you put a wolf to save chickens?
As you can see, the food pyramid has not always promoted a balanced diet and a healthy lifestyle. Quite the contrary, it has been used as a tool in favor of the economic interest to the detriment of the health.
In the last few years have been published new improved versions the pyramids of food, although they still contain errors or claims without scientific backing: in the base continue to appear in cereals, do not distinguish between saturated fats and put in place, the eggs have a negligible role,...
As a recommendation, since the evolutionary point of view the pyramid of healthy food that makes more sense is: fruits and vegetables in the base, fish and eggs in the next level, oils, nuts, meats and dairy at the next-to-last, and finally, grains and legumes.
Without a doubt, we encourage you to try this last food pyramid-evolutionary.
Your health will thank you!
Pyramid u.s. Department of Agriculture (USDA): Wikipedia