Vitamins are one of the most important things that you feed your body on a daily basis. With only two exceptions, your body is unable to produce vitamins and must rely on getting them through diet alone. Though they provide no calories to you, your body would be rendered useless without them. A lack of vitamins can make you tired, weak, short of breath and in some cases, even colorblind.

Vitamins are what aid your bodily functions such as your metabolism, growth and energy production. For example, you probably know that most milk is fortified with vitamin D, but did you know why? It is an important tool in balancing your bloods calcium and phosphorus levels. Without vitamin D, your body can't absorb and use calcium. For this reason, it is always important if you are taking calcium supplements to make sure it also contains vitamin D to ensure your body has an adequate amount of vitamin D to process the calcium.

Water and Fat Soluble Vitamins
There are two main categories of vitamins, water-soluble and fat-soluble. Fat-soluble vitamins can be stored in your body's fat reserves until you need them. Fat-soluble vitamins include E, D, K and A. However, because you don't flush these through your system, these four vitamins in particular have a higher risk of ill side effects when overdosed.

Water-soluble vitamins, such as vitamin C cannot be stored by your body for great lengths of time and require a much more regular intake to keep you healthy. These types of vitamins are passed to your blood stream directly from your intestine. Most of these are stored only on a daily basis and excreted in your urine. There is one exception to this rule, B12, which is excreted through feces. The water-soluble vitamins in particular help your vision, digestive system and skin among other important functions.

When you're getting too much
There is too much of a good thing, even when it comes to vitamins. For example, too many carrots can cause your skin to turn orange from the Beta-Carotene and vitamin A. Too much vitamin C, a vitamin abundantly found in oranges, can cause much more serious side effects such as kidney stones or chronic diarrhea if taken in extreme excess. Ironically, one source also indicates that extreme excess can actually cause a stuffy nose instead of prevent the common cold as most people believe it does.

When you're not getting enough
On the other hand, a lack of vitamins can cause detrimental effects. Lack of vitamin C can cause scurvy, a serious disease that can lead to death if left untreated. Other vitamin deficient related diseases include anemia, brain or nerve damage, impaired vision and a variety of bone related diseases.

However, watching your vitamin intake or using a supplement can be a very good thing, especially in the world of fast food and super sized Cokes that we live in. After analyzing your diet for holes in nutrition, you can properly determine exactly what vitamins you might be deficient in and work from there to fill in the gaps with supplements or a change in diet.