Vitamindcouncil.org is the best source of information about all the important functions of Vitamin D, on nearly every organ and system in the body. Dr. John Cannell regularly posts new research studies there from all over the world. Vitamin D is essential for your immune system to work at its peak. The immune system has two modes, breakdown and rebuild. Vitamin D is required for it to switch efficiently from one to the other. When you have adequate Vitamin D, colds and flus are rare, and mild.
The proper dose for adults is now 5000 IU per day. The paltry 400-600 IU recommended by US government is merely enough to prevent rickets. Unfortunately, there aren’t any significant dietary sources of Vitamin D. A glass of milk has only 100 IU. Fifty glasses of milk a day, anyone? Our bodies are designed to make Vitamin D in our skin. To get adequate amounts, you need to expose your torso (not just your arms and legs) to the sun for about 20 minutes (half the time it takes you to turn pink), three times a week, with no sunscreen. And in the US, this will only work in the spring, summer and fall. There aren’t enough UVB rays in the winter, even in California.
The only way to know that you’re getting enough is to do a blood test. Most doctors will order this for you. The reference range used by most physicians was recently raised from 20 to 32 ng/ml. This is still too low. Current research shows that the healthy range is 50-80 ng/ml. People who live near the equator, and spend time outdoors (without a shirt on) have this level in their blood. They also have very low rates of heart disease, diabetes, depression, dementia, breast, prostate and colorectal cancer, and many other conditions that are common elsewhere. Nearly everyone in the industrialized world tests far below the healthy range, unless they take 5000 IU daily.
Call our office if you’d like us to order the blood test for you. It’s $40, and can be done at any one of thousands of LabCorp draw sites around the country.