Unit 9
The Vitamins

The word vitamin is derived from the Latin noun vita (life) and amine, referring to the nitrogen-containing group detected in the first vitamins discovered. The word was originally spelled vitamine; however, when it was realized that not all vitamins contained an amine group, the e was dropped.

Although the history of vitamin deficiencies dates back to at least the ancient Egyptians, most of the vitamins we know today were discovered in the first half of the twentieth century. They were originally named alphabetically, in the order that they were identified. Later, when the vitamin B present in semi-purified materials was found to contain several active substances, numerical subscripts were introduced.

In recent years, researchers have learned about the role of vitamins in preventing chronic disease. Folate, vitamin D, and carotenoids (vitamin A precursors) all appear to have roles in lowering risks for heart disease or cancer.

In this unit, we discuss the characteristics, sources, physiological activity, deficiency symptoms, and stability of the major vitamins.

Objectives

After completing this unit, you should be able to

1. describe the general characteristics of vitamins.
2. discuss the differences between water- and fat-soluble vitamins regarding the body’s absorption, storage, and excretion; potential toxicity to the body; and retention in food through processing and storage.
3. list dietary sources, symptoms of deficiency, Canadian populations vulnerable to deficiencies, and body systems affected by toxicity (as applicable) for vitamins A, D, E, C, B₆, B₁₂, thiamin, riboflavin, niacin, and folate.
4. describe functions of vitamins A (seven), D (two), C (five), B₆ (five), B₁₂ (five), and folate (five). Describe two main roles for each of vitamin E, thiamin, riboflavin, and niacin.
5. identify the food group(s) which typically contain each vitamin in Objective 4, and list three to five food sources of each vitamin.
6. distinguish dietary sources of the retinol and beta-carotene forms of vitamin A.
7. discuss at least six vegetable storage and preparation methods that maximize retention of water-soluble vitamins and minerals.
8. discuss the consequences of refining and enriching grains on vitamin and mineral content.