Unit 8
Water-soluble Vitamins: The B-vitamins and Vitamin C

The word vitamin is derived from the Latin word vita, meaning life, and amine, referring to the nitrogen-containing group discovered in the first known vitamins. When it was realized that not all vitamins contain an amine group, the “e” was dropped.

Although the history of awareness 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 in which they were identified. Later, when the “vitamin B” present in semi-purified materials was found to contain several active substances, numerical subscripts were introduced, which led to some confusion. These letters and numbers are still used for about half the vitamins, while names are preferred for the rest.

Today, about 13 vitamins are generally accepted as essential. We will discuss them in this unit and the next.

In this unit, we examine the general characteristics of vitamins and the differences between water-soluble and fat-soluble vitamins. A brief overview will be provided for each B vitamin and for vitamin C, covering their functions, deficiency and toxicity, major food sources, and chemical stability. You need not memorize the RDA for any of the vitamins or minerals, but you should know their units of measure and their equivalents, if available. For reference, use the chart on the inside front cover of the textbook.

This unit consists of three sections:

8.1—General Characteristics of Vitamins
8.2—The B Vitamins
8.3—Vitamin C

Objectives

After completing this unit, you should be able to

1. compare the general characteristics of vitamins to those of carbohydrates, lipids, and proteins.
2. compare the characteristics of water-soluble and fat-soluble vitamins.
3. describe/discuss the following aspects about each of the following vitamins: thiamin, riboflavin, niacin, vitamin B-6, folate, and vitamin B-12.
   1. Identify its functions in the body.
   2. Describe its deficiency and toxicity symptoms.
   3. List some of its major food sources.
   4. Discuss its chemical stability with respect to food preparation practices and other factors.
4. describe/discuss the following aspects related to vitamin C:
   1. Identify its functions in the body.
   2. Describe its deficiency and toxicity symptoms.
   3. Describe factors that may influence requirements.
   4. List some of its major food sources.
   5. Discuss its chemical stability with respect to food preparation practices and other factors.
   6. Discuss the controversies associated with its use.