Unit 3
The Concept of Chronic Diseases of Lifestyle

Overview

In this unit, we explore the most important concept in modern nutrition; namely, that the major non-infectious diseases present in Western countries, such as Canada, are caused by lifestyle and are largely absent in populations that have not adopted that lifestyle. These diseases have been known by different names, including Western diseases and non-communicable diseases. In this unit we will use the most common name: chronic diseases of lifestyle (CDL). These diseases, listed below, include many of the most common causes of sickness and death in Canada.

  1. coronary heart disease (CHD): the second most common cause of death (just behind cancer)
  2. stroke: the third most common cause of death
    1. Other common disorders of the circulatory system are hypertension (the major cause of stroke), varicose veins, and thromboembolism, which occurs when a clot forms in a vein and then breaks away and lodges in the lung.
  3. the three most common cancers of women (lung, colon, and breast) and of men (lung, colon, and prostate)
  4. several of the major metabolic diseases: obesity, gallstones, kidney stones, osteoporosis, and type 2 diabetes
  5. several of the most common gastro-intestinal disorders: constipation, hiatus hernia, appendicitis, diverticular disease, and hemorrhoids
  6. dental caries

It is important to understand that these diseases are largely or entirely absent in populations which are truly non-Western. This fact does not mean that they are absent in all developing countries, however. Although many developing countries have a low level of technological development, they often produce or import large quantities of “Western type” foodstuffs, as well as cigarettes. Consequently, chronic, lifestyle-related diseases are becoming increasingly common, particularly in the cities and among the wealthier members of society.

The concept of CLD arose from comparative studies of disease incidence in Westernized and non-Westernized populations. Therefore, to understand the concept, it is necessary to examine the usual diets of these societies.

Objectives

After completing this unit, you should be able to

  1. identify and briefly describe the chronic diseases related to lifestyle.
  2. describe, in general terms, the historical and geographical occurrence of these diseases.
  3. compare the Western diet with traditional human diets, namely the paleolithic diet and the diet eaten by members of modern pre-industrial societies.
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