* Many adults are vitamin D deficient.
* People most likely to suffering of lack of vitamin D are the elder, people who need to avoid sunlight due to skin conditions, dark-skin people, and people unable to absorb the vitamin D for various reasons.
* It is recommended daily exposure of at least parts of the body to sunlight for the synthesis of vitamin D. It is recommended sunbath between 10 AM and 2 PM in summer should be avoided.
* It is recommended 400 IU of vitamin D supplementation a day.

Vitamin D
Vitamin D is composed of two molecules; Cholecalciferol, known as Vitamin D3, and Ergocalciferol which is also referred to as Vitamin D2. Cholecalciferol is synthesized by UV light in the skin. Ergocalciferol is the form of Vitamin D extracted from plants which have been exposed to and absorb UV light.

Vitamin D is an important part of a healthy diet to promote proper bone function and strength. Working in part with calcium, Vitamin D provides bones with the nutrients needed to maintain strong and healthy bones, preventing fractures, breaks and bone loss.

Once ingested Vitamin D is metabolized by the liver, and then hydroxylated in the kidneys to produce the most active form, to facilitate the absorption of phosphate and calcium, mineralization of the skeleton and extracellular homeostasis with the help of parathyroid hormones.
Recommended Dosage of Vitamin D

The majority of Vitamin D retained by adults is from sunlight; however it is important to note that Vitamin D consumption should not be based only on sunlight. Adults should consume about 400 IU daily. Sunlight exposure for an average of 15 minutes yields absorption of 1/3 of the minimal erythemal dose.
While sunblock is important for prolonged sun exposure to prevent damage to skin, direct short exposure of the hands, arms and face to the sun while it is not intense is recommended for about 15 minutes. Sunblock prevents the penetration of UVA and UVB rays from the sun; UV rays are the necessary component for Vitamin D synthesis. During hotter months, it is advised to avoid direct sun exposure without sun block between 10AM and 2AM to prevent risks of serious skin damage.

Vitamin D is also found in several foods. Listed from highest to lowest IU value, they are: salmon, mackerel, tuna fish, fortified milk, fortified margarine, egg yolk and beef liver. Pure cod liver oil supplements are also a good source of Vitamin D, yielding a high IU value for a small amount. Since most adults consume less than 100 IU daily from diet, supplemental forms of Vitamin D are recommended, especially for those who do not receive proper sun exposure.

The recommended intake by the FDA is:
Vitamin D intake – Daily intake
Age / IU / mcg
0 – 50 / 200 / 5
51 – 70 / 400 / 10
71 + / 600 / 15

Groups at risk
Certain adults are more at risk than others. Generally the elderly are most susceptible to more serious Vitamin D deficiencies. This group usually does not receive as much sun exposure or consume as many foods with Vitamin D. Supplements are very highly recommended for the elderly. Hospital patients, especially those with hip fractures are also more susceptible to deficiencies of Vitamin D. Women who have a very dark skin tone are also at a very high risk; if the woman is usually veiled, this factor increases the risk further.

Vitamin D deficiency
Vitamin D deficiencies are classified in three different forms: mild, moderate and severe. Each deficiency is rated on a scale level of 25-OHD.

Mild vitamin D deficiency ranges between 25-50 nmol/L and result in the increase of secretions of parathyroid hormones and higher bone turnover.
Moderate vitamin deficiency ranges between 12.5-25 nmol/L and results in higher bone turnover and reduced density; usually a higher risk of hip fracture is associated with moderate deficiency as well.

Severe vitamin D deficiency rank below 12.5 nmol/L; results of severe deficiency are osteomalacia. Persons with osteomalacia experience pain in muscles and bones, along with frequent and severe fractures.

Toxicity
Toxicity is caused by excess ingestion of vitamin D supplementation not by exposure to the sunlight. There are no evidences of toxicity by doses lower than 4 000 IU daily.

Vitamin D and Prostate Cancer
Prostate cancer is one of the major cause of deaths. Every year about 220,000 men are diagnosed with prostate cancer in the USA. Doctors may sustain that vitamin D is not beneficial for cancer of the prostate until further studies proves its help.

Following that approach two things can happen: The patient may die while the conclusions of such studies are still pending or it can miss the point. Men diagnosed with cancer in the prostate cannot afford to be vitamin D deficient and neither should do their doctors although vitamin D should not be considered as the only treatment of prostate cancer. Evidences suggest that the proper intake of vitamin D3 may help fighting prostate cancer.

Vitamin D Acknowledgments
A paper from Feldman and the Stanford University states: “Based on these findings, we postulate that vitamin D may have protective actions on the development and/or progression of prostate cancer…We further hypothesize that vitamin D supplementation may have beneficial effects on retarding the development and/or progression of prostate cancer.” This is the first evidence of the usefulness of the Cholecalciferol in the prevention and treating of prostate cancer. Cholecalciferol, Calcidiol and Calcitriol.

Several scientific studies have been conducted since 1998 by American universities on vitamin D and its role in the prevention and treatment of prostate cancer. It was found that the vitamin D raises the level of plasma calcidiol. The Calcitriol is made by the kidneys from the calcidiol which has been considered as beneficial for the treatment of prostate cancer. The easiest way to raise calcidiol levels is through supplementation of Cholecalciferol.

Further studies show that calcidiol is just as effective as calcitriol in inhibiting prostate cancer growth.
Calcitriol Breakdown Reduced by Soy Isoflavonoids
In 2003, two studies from at the University of Vienna Medical School confirmed that the isoflavonoids in soy dramatically reduce the breakdown of calcitriol in prostate cancer cells. In fact, they found that such products profoundly inhibit the enzyme that metabolizes calcitriol, reducing its activity to almost zero. This again raised the possibility that such compounds could be combined with vitamin D to treat prostate cancer. A study from the University of Toronto presented by Woo, Vieth, in 2004 showed that 2,000 IU of simple vitamin D3 (Cholecalciferol) either reduced or prevented further increases in PSA in the majority of men with advancing prostate cancer.

Vitamin D supplementation
There are a few supplements of concentrated form of Vitamin D available used to treat Vitamin D deficiencies. Most supplements contain the highest level of 1,000 IU. Depending on the severity of deficiency, it may be required supplementation between 3,000 and 5,000 IU daily for adequate replacement therapy.

Other supplements containing Vitamin D address specific issues but depending on the formulation they can also be used for general use or other. Some formulations for helping prostate health contain 1,600 IU of Vitamin D3 in one single dose. Prostate-C is considered one of the best products available and can be found online.