Food is the domain of all that relates to food for a living organism to function.

By extrapolation is defined as any power secondary system which ensures the provision of basic and primary energy to a system dependent for its first operation. In the technical field and we talk for example power or fuel for a combustion engine. This understanding will not be developed in this article on the food function in the life sciences.

Food is responsible for approximately 3 / 4 of the ecological footprint of individuals (?) and is one of the major issues of health and sustainable development.

Biological approach
The chemical reactions necessary to life are dependent on nutrient intakes. In higher organisms they are either synthesized through photosynthesis (plants) or drawn into organic compounds (animals and fungi). There are other energy sources for micro-organisms: for example, some archaea derive their energy by producing methane by oxidizing sulfur compounds.

Healthy Eating
For humans, a healthy diet is to follow a balanced diet, that is to say to eat too much or too little of key nutrients such as vitamins and trace elements, proteins, fruits, vegetables and take his meals preferably at regular times.

Some traditional diets have a favorable impact on health. The inhabitants of the Japanese island of Okinawa have the life expectancy is longer in the world. Their diet has many similarities with that of the "Mediterranean diet": use oil, no animal fats, consumption of vegetables and fish diet frugal. But it seems desirable to ask the question of their microbiota for understanding why these facts. healthy eating is not a deprivation of food, but a diversification of the latter.

The food goes into the factors that may affect life expectancy. A team of researchers from the University of Cambridge (United Kingdom), in partnership with the Medical Research Council, conducted a survey on 20 244 individuals for 14 years (1993-2007), of which 1987 died during investigation to determine the impact of lifestyle on life expectancy. The study concludes that the "ideal way of life" - no tobacco, alcohol or less half a glass a day, eating 5 fruits and vegetables daily, exercise for half an hour a day - bound the life expectancy of 14 years compared to the total of four risk factors. The accumulation of four risk factors (tobacco, alcohol, lack of fruits and vegetables and exercise) increases the risk of death by 4.4, three factors of 2.5, two factors of almost 2 to 1 factor 1.4. According to Professor Kay-Tee Khaw, the first signatory of the study, "this is the first time we analyze the cumulative effect of risk factors on mortality.

Recent developments in developed societies
The current way of life in developed societies threatens to undermine the principles of healthy eating.

Obesity is steadily increasing in the world including in France for 30 years. She now covers 8% of adults and 10% of children: a fringe of increasingly large and young population. Eating habits harmful to health are being developed:

* Consumption of soft drinks, ice cream, sweet desserts and products containing simple sugars;
* Diets nutritionally unbalanced and generally cons-productive as followed later feeding periods even richer;
* Snacking on fatty foods and sugary (encompasses 60% of teenagers), that cut hunger for foods helpful;
* Prepared dishes too much salt (which increases sharply hypertension and always encouraged to eat more salt), and few fresh foods (so fewer vitamins in particular).
* Consumption of processed foods containing a large number of chemical additives often. "Most processed foods are so processed and contain many additives it is almost impossible to know what you eat and, more importantly, what are the consequences of such a type of food medium and long term . "Argue in essence about 2007 Catherine Vialard Ruchon-Duran and Bernard, author of a three-year investigation on food.

The World Health Organization (WHO) launched an extensive campaign to promote healthier eating. In France, the National Health and Nutrition (PNNS, Ministry of Health) specifically encourages consumption of fruits and vegetables more important (slogan: 5 fruit and vegetables a day).

However, the twenty-first century, part of the population in developed countries facing problems of malnutrition are linked to the difficulty of this population to have sufficient income to eat well, what is called food security.

Situation in developing countries and LDCs
* Improved Quantitative

In contrast to the problems of food consumption in industrialized countries, hunger is still prevalent in the newly industrializing countries and regions in the traditional ways of life.

Yet signs of improvement are visible: food insecurity declined from half a century. Only 13% of people worldwide are malnourished as against 37% in the early 1970s. For others the amount of food available to each individual reaches the limit set by FAO, that is to say 2500 calories per day.

However, undernutrition still concerns 854 million people worldwide. Yet experts agree that global agriculture can probably feed 12 billion people. The only question that arises is that of food distribution.

Undernutrition is due to food shortage could be caused by:

* political instability or armed conflict. Take the example of Darfur.
* natural disasters (eg droughts or floods in Mauritania in India).

The food shortage causes a rapid increase in prices of food, depriving them of access to food for the poorest populations. Africa, Asia, South East and the Middle East are the main areas where lack of food is the most important.

* Qualitative improvement:

The diet of traditional societies is based on one main product (a grain like rice, maize, wheat), where a certain monotony in the meals. Most countries are experiencing or have experienced what is called the nutrition transition, which is characterized by a more balanced improvement, where consumption of vegetables, dairy and meat rose.

Cultural approach
Food is, with perhaps reproduction, one of the only basic physiological activities have stimulated much the various human cultures. Human beings have invented a particular practice to decorate the best food: cooking. He also sought to streamline their practice, creating the best diet to meet their nutritional needs.

The cultural approach to food has been highlighted by social anthropologists in the last century [when?]. In this sense, man does not eat that food but also symbols of the imagination. The principle of inclusion involves the appropriation of qualities of food by the eater. The action to incorporate consequently gives the eater the attributes of the food ingested. According to geographical locations, the habitat and culture of each company, the food is value-laden, meaning and the principle of incorporation takes its theoretical validity. The Maasai, for example, do not eat because the pitches when attacked, he took a defensive posture and folds on itself, this behavior is considered "cowardly" by the Maasai and they do not consume to avoid not take its attributes during incorporation. Man does not arbitrarily consumes food and each culture has food codes. The man eats so through cultural rules and requirements. Cultures that are in the same habitat will tend to differentiate between them by choosing the order of the edible (Jean-Pierre Poulain) respectively.