Everyone associates Vitamin D with Rickets due to the role it plays in our ability to absorb calcium, but it does so much more.  Here are just a few things Vitamin D deficiencies have been associated with (autoimmune diseases, weight gain, hypertension, psoriasis, eczema, insomnia, hearing loss, muscle pain, periodontal disease, athletic performance, age related macular degeneration, myopia, pre eclampsia, seizures, fertility, asthma, cystic fibrosis, migraines, depression, alzheimer's and schizophrenia).

Some very good studies have shown that Vitamin D may reduce the risk of developing certain types of cancers such as breast, colon and prostate. If you're a geek like I am, then give this study a read (
http://www.biomedcentral.com/1471-2407/6/264/).  They looked at 3 million incidents of cancer and 3 million cancer deaths, and compared that against UV-B exposure by location.

Vitamin D is a potent antibiotic, producing very specific antimicrobial peptides.  Cathelicidin is an antimicrobial peptide that is regulated by Vitamin D and appears to dramatically reduce the risk of death from infection for dialysis patients.  A study found that patients with high levels of this peptide were 3.7 times more likely to survive kidney dialysis for a year without a fatal infection.

Gene regulation is the big one though.  Vitamin D is used in the regulation of over 2,000 genes!!!  Before the Human Genome Project, it was estimated that humans had as many as 2,000,000 different genes.  Now it's estimated to be between 20,000 - 25,000 and Vitamin D is used to regulate 2,000!  Let's pause for a moment and think about that. [pause] Ok, we're back.

How do our bodies normally get Vitamin D?  Great question!  We are designed to make it from exposure to the sun.  Here's the recipe... take 4 UVB photons and 1 molecule of cholestorol (specifically 7-DHC) and you get Vitamin D3.  Your liver then converts Vitamin D3 to 25(OH)D3 and then finally your tissues convert it to its active form of 1,25(OH)2D3 where it's needed.  The challenge is getting enough Vitamin D3 and if you're not getting enough sun then you need to supplement it.

How much should I take?  
Um... I don't know.  You need to get tested.  This is a blood test that can be done by your doctor, at a lab or at home and sent to a lab. Make sure the test is measuring 25(OH)D3 and NOT 1,25(OH)2D3.  The current literature is suggesting an optimum level of about 60ng/ml and you don't want to exceed 100ng/ml.  A few examples of what these levels mean... 25(OH)D3 levels at 5ng/ml reduces the risk of developing rickets by 50% and at levels above 20ng/ml reduces the risk by 99%.  Levels at 35ng/ml reduces the risk of Type 1 Diabetes by 50% and levels around 50ng/ml reduces the risk by 80%.  Levels over 50ng/ml reduces the risk of all cancers combined by about 75%.

Typical doses for adults are 2,000 - 5,000 units per day, but a person might need much more than that to reach and maintain their optimum level.

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