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 the three sections listed below.

• Section 8.1  General Characteristics of Vitamins
• Section 8.2  The B Vitamins
• Section 8.3  Vitamin C