The short answer is, "all of them, in appropriate amounts."

A Vitamin is a category of organic molecule that is required by a living organism for normal health. Vitamins are often referred to as "micronutrients" because as a percentage they make up the smallest portion of the foods we eat in a healthy diet. If deprived of all sources of a particular vitamin you will eventually suffer from disease symptoms specific to the missing vitamin. Once such disease is called Scurvy and was once a leading cause of death among Europeans until 1747 when it was established that citrus fruits and even sauerkraut would prevent the disease and "cure it" in those who were already suffering from Scurvy. In spite of this discovery, it took nearly 100 years for the population to accept this relationship between diet and such a horrible disease. In the early 1900s the molecules were identified in these foods and eventually referred to as vitamins.

The naming convention of vitamins was a bit disorganized and some vitamins were later classified as other types of nutritional components. For example, the Nobel Prize winning research for the discovery of Vitamin C also refers to a necessary "Vitamin P" that is now known as the flavonoid family of molecules. This was done as the definition of vitamins was further refined and agreed upon.

As a category of nutrition, vitamins are essential for life; they are not stored in the body and cannot be created by the body. Vitamin A is converted from carotenes, after the ingestion of certain fruits and vegetables, but still cannot be created without those necessary "building blocks." Similarly, Vitamin D can be produced in the skin by someone who receives regular exposure to sunlight and is not wearing sun

When choosing a supplement, first understand that nutrition should be appropriate in amount, high in quality as well as complete. It is better to choose a high-quality multivitamin than an assortment of individual vitamin supplements. Also, vitamin supplements should be food-matrix and standardized. This ensures the vitamins are properly utilized in the body and that each and every supplement is providing the same amount of active ingredient as the last. Most of the top selling brands of vitamins are neither food-matrix, nor standardized, so do your own research and only supplement your good diet with a top-quality vitamin supplements.

Finally, remember that supplementation is intended to improve nutrition and ensure that you are receiving appropriate levels of micronutrients in your diet each day. Supplements are not intended to replace the need for a good diet, but instead to make up for the reality that we live in times when it is necessary to improve the diet through supplementation to ensure balanced nutrition.

When someone asks you "What vitamin should I take?" you should now know that it is important to take a balanced, high-quality multivitamin first. After you have established a baseline of nutritional supplementation, give yourself a few months and then research individual vitamins if your personal nutritional needs require a bit more of one vitamin over another. You can then add individual, high-quality vitamin supplements to your multivitamin use. Maybe people find that additional vitamin supplements are not necessary and that a high-quality multivitamin improves their energy and sense of well being without the need for additional doses of individual vitamins.
About the Author

Dave Saunders is a professional lecturer, and certified nutritional educator. He enjoys creating interconnections through his writings and lectures to help others create context and see new discoveries and technologies in more a practical light. You can find out more about new discoveries in health and nutrition at www.glycoboy.com.