The human body is an amazing machine, but it is not self-sufficient. Short or tall, fat or skinny, young or old - every body depends on several different types of vitamins and minerals in order to perform efficiently and stay healthy. The human body is able to produce its own niacin, biotin, and vitamin D, but we get all of the other vitamins and minerals strictly from food sources.

Before the 20th-century, not much was known about vitamins and minerals or the foods that contained these key nutrients. There was no scientific research or commercially available multivitamins. Many people did not even have access to nutrient-rich foods. Because of this, millions of people suffered from vitamin-deficiency diseases like scurvy and rickets.

In the early 1900s, scientists carefully studied the role that vitamins and minerals play in the human body. We now know that humans need 13 types of vitamins (made by plants or animals) and 16 kinds of minerals (inorganic elements that come from the earth). Going without these nutrients can lead to serious health complications like blindness, liver damage, cardiovascular disease, birth defects, and many others. Thankfully, many of these conditions can be avoided by eating a balanced diet and, if necessary, taking medical supplements.

This guide identifies the vitamins and minerals which are essential for health and fitness, and also explains which foods contain normal dietary requirements of these supplements. It also shows how some vitamins can be harmful if high levels are ingested, and which foods help to maintain a balanced and nutritious diet.