Man is an individual with his own character. His physical attributes can also differ greatly from those of his neighbor. The needs of each individual depend on their age, weight, height and genetic characteristics, to name a few. A healthy diet must therefore be specifically applied to an individual. Some general rules can be generalized to a group of people. 
Genetic variation affects the metabolism of humans and at the same time determines which foods are suitable for a person and which are not. For example, in certain cases, algae prevent some foods from being consumed at all.