The intelligence is not something an individual is born with. Rather, it depends on the environment in which the individual grows and develops as a human being and on the way in which that person uses their brain. It is very well known that external factors have a great contribution in the way the brain evolves during the individual's life. How much that individual reads and has cultural activities, the social background in which that individual lives and the stress to which a person is supposed are factors which influence the brain development and thus the IQ.
Yet, what most people do not know is that the food they eat has also a great influence upon the brain and upon the way in which the intellectual abilities evolve along the years. There have been numerous articles triggering an alarm signal regarding the damaging effects that fatty foods and fast foods in general have upon health, but it has almost never been emphasized that in addition to health problems, the fast foods are also highly damaging for the brain as they stop any further evolution of the intellect. There have been cases in which the unhealthy diets have lead not only to a stop in the intelligence evolution, but to a regression of the IQ. This is why, it I recommendable that you think twice when eating unhealthy foods.
Basically, the foods which should be avoided in order to maintain the brain healthy and in good function are those containing high amounts of chemical substances, high amounts of sugar and of saturated fats. These are not only real threats to the silhouette and to the skin, but they have also devastating effects upon the brain.
So, if really want to have both a healthy body and a brain which works good in any situation you should definitely give up sugary foods, pastries, fatty foods and sodas! You will see that after only a short period of eating healthy food your mood will improve and your brain will start functioning in a more alert way.