Each one of us wants the latest information on which foods or supplements hold the key to good health and vitality.

A vast amount of such information is being heralded today and is often contradictory. Experts urge the public to remember that the scientific process is a long, winding road that often hits a dead end. Basically, a study rarely provides a definitive answer. Here are some definitions to keep at the back of your mind when you are reading about new health/nutritional research.

Observational research involves examining specific factors in defined groups of subjects in order to investigate relationships between those factors and aspects of health or illness. It can only suggest relationships; Controlled experiments involve study subjects -- selected according to relevant characteristics -- who are then randomly assigned to either an experimental group or a control group. The experimental group is given treatment and the results are compared to the control group which does not receive treatment. Controlled experiments can be fraught with errors; Epidemiological research is the study of distribution and determinants of disease or other health outcomes in human populations. It tries to expose potential associations between aspects of health, diet, lifestyle and other factors within a population. They do not necessarily indicate cause and effect but are useful for suggesting relationships between two factors. They can be observational or experimental; Basic research generates data by investigating biochemical substances or biological processes. It is often undertaken to confirm observations or discover how a process works, It may be conducted in test tubes or with animals; and Clinical trials deal with the experimental study of humans. Trials may be attempted to determine whether the findings of basic research are applicable to humans or to confirm the results of epidemiological research.