tely nourished (although poverty, and even destitution, remains a major problem in most big cities). On the other hand, urban populations are at increased risk of chronic diseases such as obesity, type 2 diabetes, coronary heart disease, and also some cancers.
Human Health And Diet
Health does not simply mean ‘absence of disease’ or ‘physical fitness’. It could be defined as a state of complete physical, mental and social well-being. When people are healthy, they are more efficient at work. This increases productivity and brings economic prosperity. Health also increases longevity of people and reduces infant and maternal mortality.
Balanced diet, personal hygiene and regular exercise are very important to maintain good health. Awareness about diseases and their effect on different bodily functions, vaccination (immunization) against infectious diseases, proper disposal of wastes, control of vectors and maintenance of hygienic food and water resources are necessary for achieving good health.
Diseases can be broadly grouped into infectious and non-infectious. Diseases which are easily transmitted from one person to another are called infectious diseases. Infectious diseases are very common and every one of us suffers from these at some time or other. Some of the infectious diseases like AIDS are fatal.
Among non-infectious diseases, cancer is the major cause of death. Drug and alcohol abuse also affect our health adversely. Modern diet has certainly carved up the third World due to globalization. It is an integral part of life in the developed and also the developing world, and coming with it is a massive increase in obesity and associated problems. The key to eating these junk foods is moderation, occasional consumption and preferably in small portions. It is not impossible to win battle with junk foods against healthy foods . However, one must beware entice is so strong that you will be addicted.
In term of the relationship between modern diet and health, the following four key problems have to be addressed:
(I) Under-nutrition causes nutrition deficiency, and over nutrition leads to obesity, hypertension, hyperlipidemia, diabetes, and cancer.
It also highlights that nutritional requirements of the body may vary among different individuals with different heredity and family backgrounds, different dietary habits, and living in different countries. Even different gut microbes may affect the requirement of nutrition. Although a research on personalized nutrition and nutritional genomics is proposed, results from epigenetic studies have shown that dietary habits and experience of a person can change epigenetic characteristics through DNA imprinting and histone modification. This indicates that dietary requirements are not decided by genome. Diets determine the expression, regulation, modification, imprinting, and heredity of the genome without altering DNA sequences. Obviously, this is a challenge for nutritional genomics. Thus, the problem seems to be at the origin, i.e., how to provide a scientific diet and formula for different individuals?
(II) Contribution of foods and nutrition to the immune system is apparent, which is also a hot topic of research on functional foods.
However, increasing number of studies indicate that immune defense is the first priority of nutrition. Hypo-immunity is only observed in infants, children, and elderly and in individuals with diseases and serious nutrition defects. Thus, when nutrition is abundant, even commonly redundant, excessive immunity can cause inflammation, autoimmune diseases, and metabolic syndromes. Like a double-edged sword, immunity can cause diseases when it is too low or too high. Therefore, the question is what is the appropriate immunity and how should it be quantified. Unfortunately, no method is available to quantify the immune system thus far.
(III) Another problem is that precise effect of foods on organs or tissues within the body is unclear.
Some studies have shown that food mainly interacts with the GI mucous membrane system. Communication between organs and tiss