Michael Holick, MD, Phd, who is one of the world's leading vitamin D researchers, has written a book titled The Vitamin D Solution. I highly recommend this book. The information about vitamin D is so important and so compelling that most people who read it are motivated to take action.
Dr. Holick made the following important statement, "Vitamin D is not only the most common nutritional deficiency in the world, but it is also the most common medical condition, affecting at least one billion people." An excerpt from Dr. Holick's book appeared in the September 2010 issue of the Life Extension Magazine.
Vitamin D is made in our body when natural sunlight strikes our skin. But, most people do not get enough sun exposure. That's why I encourage people to take a daily vitamin D supplement. I recommend that adults take 5,000 IU of vitamin D daily. Since vitamin D is a fat-soluble nutrient, it should be taken at the largest meal of the day to enhance absorption.
Vitamin D was discovered in 1922 when it was found to prevent rickets in dogs. Because it was the fourth vitamin to be discovered (after vitamins A, B and C) it was named vitamin D. For over half a century, scientists thought vitamin D’s only function was to enhance calcium absorption and help prevent bone diseases like rickets and osteoporosis.
More recently, scientists have discovered that virtually all cells in the body have vitamin D receptors. In addition to bone health, we now know that optimal vitamin D levels are important for the prevention of heart disease, cancer, depression, cognitive decline and dementia. Also, vitamin D is one of the most critical factors for a healthy immune system and healthy pregnancies.
Vitamin D’s importance for a strong immune system has lead scientists to the realization that the annual increase in winter colds and flu is basically a vitamin D deficiency disease. Our primary source of vitamin D is direct exposure of sunlight on our skin. In the winter months, the sun’s rays are less direct and cold temperatures cause people to stay indoors more and wear clothing that prevents sunlight striking the skin.
What is the “optimal” vitamin D level? The accepted method of determining vitamin D is to measure blood levels of 25 hydroxy vitamin D. Many laboratories list 30 ng/ml (nanograms per milliliter) and above as being optimal but I think this is wrong. The world’s leading vitamin D researchers uniformly agree that optimal vitamin D levels should be between 50-70 ng/ml. The only way to really know your vitamin D status is to get yourself tested. However, my general recommendation for adults is 5,000 IU/day.
THE VITAMIN D COUNCIL'S RECOMMENDED 25 HYDROXY VITAMIN D LEVELS:
Deficient: Below 50 ng/ml
Optimal: 50-70 ng/ml
Treating Cancers & Heart Disease: 70-100 ng/ml
Excess: Over 100 ng/ml
Did you know there are two forms of vitamin D? Vitamin D2, which is synthetic, is not the form of vitamin D that is produced in the body. Vitamin D3 is natural vitamin D, which is identical to the vitamin D our body makes. Many physicians write prescriptions which instruct patients to take 50,000 IU of vitamin D2 once weekly. However, I think it is better to take the active D3 at a dose of 5,000 IU once daily.
According to a recent study, vitamin D3 is much better absorbed, making it approximately 87% more effective in raising and maintaining blood levels of vitamin D. Vitamin D3 also stays in the body 2 to 3 times longer than an equivalent amount of vitamin D2.