What Does Vitamin D Do?

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Everyone knows that vitamins are essential for the body. Vitamins are micronutrients in the sense that they are needed in very small amounts, but they are nonetheless essential in the sense that if they are not present in the body, they can cause a number of problems.

The most common need for vitamin, one that everyone knows, is that it is essential to maintain healthy bones. Also the fact that it is synthesized in the body from sunlight is common knowledge. Lately with more research going into vitamin D, new information on how it may be useful in a number of hitherto unknown ways is coming out.

Let us now take an in depth look into vitamin D and its functions in the body.

What is vitamin D?

Vitamin D is a secosteroid and until lately was considered important because it helped the cells of the body absorb calcium and phosphate from the blood. It was very important because deficiency of vitamin D meant that there was a risk of developing rickets in children and brittle bones in the elderly.

Lately however it has been found that vitamin D affects neuromuscular function and inflammation and also plays an important role in the action of genes that regulate cell division in the body.

How do we get vitamin D?

There are two ways in which we can get vitamin D, one is in the food we eat and the other is by synthesizing it ourselves. The body’s requirement of vitamin D is usually met through both these ways. The recommended dosage of vitamin D per day for most healthy adults is around 500 IU (IU is the unit for measuring vitamins and is the acronym for International Unit). There have been no adverse effects noticed with excessive intake of vitamin D and although there is no proof of this as yet, there is a belief that the body is able to stock up on vitamin D.

Where do I get vitamin D3?

Although vitamins are available over the counter as supplements it is recommended that we get our daily requirement from natural sources. The best sources of vitamin D is seafood, especially catfish, salmon, mackerel, sardines, tuna and eels. Good animal sources of the vitamin are eggs, liver, fish oils and UV irradiated mushrooms and yeast.

The other main source of vitamin D is through sunlight. What happens is that when you walk out in the sun, 7-dehydrocholesterol which is present in the skin and is a derivative of normal cholesterol, gets converted to Vitamin D in the presence of UV radiation. Because of the problem with skin cancer in certain regions there is no recommended daily amount of sunlight that is given.

Most normal people on a healthy diet are however able to get their required quantity of vitamin D without any problems.

If a person falls deficient in 7-dehydrocholesterol then they will also be deficient in vitamin D because it is the precursor to the vitamin. There is also a slight difference between the vitamin D that we get from food and the vitamin D that is synthesized in our bodies.

Vitamin D that is synthesized is generally referred to as Vitamin D₃ and the vitamin D that is taken in through food is vitamin D₂. There is no difference between the two in terms of what they do, just in their molecular structure which is why the difference in terminology. The general term Vitamin D can refer to either of them.

What are the benefits of vitamin D?

As previously mentioned, vitamin D is essential to help the body in the uptake of calcium and phosphorous. Although due to better nutrition the prevalence of rickets has reduced dramatically, elderly people still have problems with brittle bones. Recent research seems to suggest that this is not directly age related, but on the other hand is because elderly people generally do not go out much and are therefore not able to synthesize enough of the vitamin.

Their diet too will be very limited due to age which only compounds the problem.

Although this information was known for long, recent research seems to suggest that vitamin D also helps the body function in other ways. Even though it does not directly influence any functioning, research seems to indicate that vitamin D is important in diverse functions. What all these functions are and how exactly the vitamin helps is still under study.

How much is enough?

This is very difficult to answer. Most normal people require about 500 IU every day although this is not the body’s requirement. The remainder is synthesized by the body itself. The maximum recommended dosage of vitamin D is around 4000 IU per day, but that is for people who do not go out into sunlight at all.

This however does not seem to explain the instance of Eskimos, Yakuts and others who live in the far north and do not have access to sunlight for a number of months in a year. It seems that they are able to store vast quantities of Vitamin D in their bodies during the sunny months to be used when sunlight is lacking.

Since research is still going on it is a little difficult to answer some questions regarding vitamin D with any degree of certainty. What is known is that we need at least a couple of hours of sunlight a day, and we need to eat seafood often enough to ensure that we do not lack in essential vitamins.

Jenny Allan is the webmaster at NutritionUncovered.com where she provides practical nutrition and supplement tips and advice. If you enjoyed this article you can get FREE updates by RSS.