Vitamin D - The Sunshine Vitamin

Vitamin D is actually a hormone, meaning the body can manufacture it itself. All that's necessary is for your skin to be exposed to 10-15 minutes of sunshine. The ultraviolet rays hitting your skin enable the body to make the vitamin D it needs. However, we can also get small amounts from foods such as fish, liver and eggs. In an effort to reduce vitamin D deficiency, much of the milk sold in the U.S. contains added vitamin D. Vitamin D is essential for healthy bones. Also recent evidence suggests that it may play an important role in cancer prevention, especially colon cancer.

What is vitamin D?
There are two major forms of vitamin D, D2 also known as ergocalciferol and vitamin D3 or cholecalciferol. D2 is the most commonly found form and this is the one added to milk for vitamin fortification, and most commonly found in vitamin supplements. Vitamin D is fat soluble and can be stored in the body.

What does it do?

Regulation of calcium
One of the most important roles of vitamin D is in the regulation of calcium within the body. Vitamin D regulates the level of calcium within the blood and so is essential for keeping your bones healthy.

Cancer
There is clear evidence that vitamin D can help prevent colon cancer and some studies have suggested it may do the same for breast and prostate cancers. The idea that vitamin D may play this role came from data which showed that people in northern climates are more likely to get colon cancer than those in the sunnier southern climates. Not only does vitamin D help prevent cancer, but it also seems to be useful in treating it and this is the subject of ongoing research.

How much do we need?
As the body gets older, we are less able to make vitamin D for ourselves and so the amounts we need rise as we age. Adequate amounts of vitamin D are:

	International Units (IU)	Micrograms
Adults
Ages 20 to 50	200	5
Ages 51 to 70	400	10
Ages over 70	600-800	10
Children	200	5

Deficiencies
Vitamin D deficiency is not very common in children today, mainly due to the fortification of milk with vitamin D. However, at one time, it was relatively common and caused rickets, a disease in which a child's bones did not form properly.

The most common reason for a deficiency is a lack of exposure to sunlight. These days we know a lot about the dangers of too much sun exposure and many of us wear sunscreen to help prevent skin cancer. So it is important that we make sure we are getting enough vitamin D in our diet to keep us healthy. On a bright sunny day the body can manufacture enough vitamin D from 10-15 minutes of exposure on your face, while on a dull winter day it may take several hours. Your body is able to store vitamin D in the fat of your body.

The main groups of people who may be at risk for becoming deficient in vitamin D are:

• Older adults - the body is less able to produce vitamin D as we age.
  
• People who do not get a lot of sunshine, either because they don't get out much , or they live in northern climates.
  
• Vegetarians - most of the vitamin D we consume comes from animal products and milk fortified with vitamin D, so vegetarians must ensure they are getting enough vitamin D.
  
• Alcoholics - alcohol reduces the body's ability to absorb vitamin D.
  

Supplementation
If you fit one of the categories of people described above who may not be getting enough vitamin D, you should consider taking a supplement. For most people taking about 200 400 IU per day as a supplement will ensure enough vitamin D.

WARNING High doses of vitamin D can be toxic. This can lead to high levels of calcium in the blood (a condition known as hypercalcemia) and calcium deposits forming in the soft tissues of the body. The symptoms include nausea, vomiting, constipation, anorexia, confusion, high blood pressure, lack of energy, severe kidney failure, and even coma. Ensure that your daily intake is less than 1000 IU per day to avoid any problems, and if you do experience any of these symptoms seek medical attention.

Summary

Vitamin D is a vitamin and a hormone

• It is fat soluble and the body can store excess
  
• The body can manufacture it's own vitamin D if the skin is exposed to direct sunlight
  
• Vitamin D is important for:
  
  • Healthy bones
    
  • Your immune system white blood cells
    
  • Preventing cancer, especially colon cancer
    
  
  
• Most foods do not contain much vitamin D, but much of the milk on sale in the U.S. is fortified with added vitamin D
  
• Excess vitamin D intake in the form of supplements can be extremely dangerous.