We are all aware of the proliferation of vitamins for purchase, in grocery stores, pharmacies, health food stores and websites. Many of us are taking vitamins or know people who do. Is it necessary to take vitamins? In order to answer this question, we should step back and answer some fundamental questions about vitamins. This will entail a discussion, which will be continued in next month’s installment, as well. To start off, what are vitamins?

A high-level definition is that a vitamin is a substance that is essential for the maintenance of normal metabolic activity in our bodies, but is not manufactured in our bodies. Therefore in order to have access to vitamins, an external source is necessary. In most cases the external source is foods; in the case of Vitamin D, the source can be food or exposure to sunlight.

In general, a healthy person who ingests a well balanced diet does receive adequate amounts of vitamins from their foods. Nonetheless, there are instances in which we may have a sub-optimal amount of vitamins in our body, in which case taking vitamin supplements can be beneficial. Before we explore these situations, let’s look at a few basic facts about vitamins.

There are two major categories of vitamins: those which are fat soluble and those which are water soluble.

If someone ingests excessive amounts of fat soluble vitamins, then these can accumulate in the body fat and actually be toxic to our bodies, causing illness. Water soluble vitamins, if ingested in excessive amounts, are usually excreted in the urine, and generally do not cause toxicity or illness. Fat-soluble vitamins include Vitamin A, Vitamin D, Vitamin K and Vitamin E. The water-soluble vitamins include all of the various B vitamins as well as Vitamin C.

There are three broad categories of circumstances in which a person can become vitamin deficient. First, vitamin deficiency can occur due to an inadequate intake. This situation could arise due to poverty, which results in healthy foods being inaccessible. In addition, people who are vegetarian or vegan can also be subject to vitamin deficiencies (particularly Vitamin B12). People who consume excess amounts of alcoholic beverages or smoke tobacco products, can also develop vitamin deficiencies.

Second, vitamin deficiency can occur in the setting of poor absorption from the gastrointestinal tract. There are many causes for this including colitis, celiac disease and other conditions that cause chronic diarrhea. In addition, diseases of the liver and biliary tract can also affect absorption. Treatment with antibiotics can negatively affect vitamin absorption from the GI tract.

The third category for vitamin deficiencies is when there are increased tissue requirements for vitamins. In a healthy young person this situation can occur when there is skeletal growth, or when there are periods of hard physical work, and for women, during pregnancy, lactation and menstruation. There are certain diseases and conditions that are associated with increased requirements for vitamins, such as infections, overactive thyroid, the recovery period from surgery, as well as cancer, and during chemotherapy or radiation therapy for cancer. Most commonly, there is good evidence that vitamin requirements increase during stressful situations, both physical or psychological.

To recap, most people get adequate amounts of vitamins when eating a well-balanced diet, but there are many common circumstances in life when vitamin deficiencies can develop.

It will be helpful to consult with a physician when taking vitamins to get optimal results. Look for part two of this discussion about vitamins in next month’s column with some interesting case studies.

Dr. Mark Roth writes about medicine for the Cleveland Jewish News. He is an internal medicine physician with University Hospitals.

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