Unit 1
General Principles of Research in Nutrition

Overview

Nutrition is a rapidly expanding science. Indeed, knowledge in the area has increased exponentially in the last three decades. Often, however, today’s discovery is tomorrow’s discredited idea. For instance, the importance of dietary factors supposedly involved in such disorders as breast cancer (fat), the common cold (vitamin C), obesity (high fat intake), hyperactivity (food additives), and stomach cancer (nitrates) have been both proven and disproven. Why is there such confusion? The perennial problem of nutrition is that it is not an exact science: rarely does it have the precision of physics or chemistry. Deductions tend to be based on ambiguous evidence.

In this unit, we look at how nutrition research is conducted. From this investigation, you can learn how to assess nutrition claims. Hence, the main part of this unit explains the different techniques for conducting nutrition research, including the advantages and disadvantages of each method. Each technique plays a role in adding to the ever-growing body of research in nutrition. The methods discussed are listed below.

  1. collection of anecdotal evidence
  2. population studies (one type of epidemiological study)
  3. historical studies
  4. case-control and cohort studies (another type of epidemiological study)
  5. cross-sectional studies
  6. intervention studies
  7. investigations into the dietary causes of disease carried out using experimental animals
  8. studies derived from biochemical and physiological research

Objectives

After completing this unit, you should be able to

  1. identify and discuss nine different types of evidence used in establishing the role of diet in disease:
    1. anecdotal evidence;
    2. evidence derived from population studies;
    3. historical evidence;
    4. evidence derived from case-control and cohort studies;
    5. evidence derived from cross-sectional studies;
    6. evidence derived from intervention studies;
    7. evidence derived from pooling studies;
    8. evidence derived from animal studies; and
    9. evidence derived from biochemical and physiological research.
  2. define placebo effect and explain how researchers control for this effect through blind trials.
  3. assess the reliability of evidence purporting to demonstrate a diet-disease relationship.
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