Vitamin D is a fat soluble vitamin we obtain mostly from sunlight and in small amounts from certain foods. Sunlight contains ultraviolet (UV) rays and it is the UV-B rays that are capable of producing vitamin D in your body by acting on the cholesterol in your skin. For almost 30 years the conventional thought around vitamin D has been that 10 minutes of sunlight on your arms and legs every day will provide the necessary amount of D.
Although this sounds like great advice it is really an oversimplification of some complicated biochemistry in your body. In order for the D producing UV-B rays to reach your skin and produce vitamin D depends on a variety of different factors:
Skin Color: Lighter skin color allows deeper penetration by UV-B rays, which decreases the amount of sunlight exposure needed for adequate vitamin D production. That means darker complexions will need longer amounts of sunlight to produce the same amount of D.
Season: if you live above 35 degrees latitude north or below 35 degrees latitude south there are little to no UV-B rays from early autumn to late spring.
Altitude: The higher you live above sea level, the greater exposure you have to UV-B rays.
Pollution and Clouds: Both of these factors influence the number of UV-B rays reaching your skin.
Age: Aging creates changes that make it difficult for UV-B rays to convert cholesterol to vitamin D. Elderly people need to rely almost exclusively on food sources rather than sunlight for their vitamin D needs.
Vitamin D Facts:
Vitamin D has been shown to influence over 2,000 genes in your body. That is why it influences so many diseases like cancer, autism, heart disease and rheumatoid arthritis. A study by Dr. William Grant, Ph.D., internationally recognized research scientist and vitamin D expert, found that about 30% of cancer deaths (that is 2 million worldwide and 200,000 in the United States) could be prevented each year by simply correcting levels of vitamin D.
Vitamin D is you best defense against colds and flu. Vitamin D regulates the expression of genes that influence your immune system to attack and destroy bacteria and viruses. People with optimal levels of Vitamin D rarely get sick.
Many research studies have concluded that up to 95% of U.S. senior citizens are deficient in Vitamin D. Those same studies show that all Americans are upwards of 85% deficient regardless of age.
Vitamin D deficiency is epidemic in adults of all ages who have a darker complexion such as those whose ancestors are from Africa, the Middle East, or India.
The increased public fear around skin cancer and the use of sun blocking agents also keeps the beneficial UV-B rays from penetrating the skin thereby adding to the Vitamin D deficiency. Many people limit their outdoor activities preventing them from getting the needed sun exposure.
Vitamin D helps your body regulate its blood sugar levels, playing an important role in preventing type II diabetes. Research shows that 60% of type 2 diabetics have vitamin D deficiency.
Studies also show very low levels of vitamin D among children, the elderly, and women.
One U.S. study of women revealed that half of African American women of childbearing age could be vitamin D deficient predisposing their children to both immune and developmental disorders.
The current Dietary Reference Intakes by the Institute of Medicine range from 200 to 600 IU per day depending on age, with the U.S. upper limit for vitamin D being 2,000 IU per day.
These numbers are out of date. They do not take into account a great deal of research on vitamin D and its effect on human health that’s been published over the last several years.
To recommend a particular dose for everyone is ridiculous given the different influences we have already discussed. I recommend that everyone get their blood levels monitored to be certain that there is a need for Vitamin D therapy, and to ensure the therapy is effective. Some will not need vitamin D while others can need as much as 50,000iu for short periods of time.
I find the majority of patients that I work with in the Chicago area need 5,000-7,000iu in the fall and winter and 3,000-5,000iu in the spring and summer. It is important to understand that in the summertime, when you sunbathe for 30 minutes, your body produces about 20,000 IUs of vitamin D. So the quantities I am recommending are not too high. No matter where you live have your serum vitamin D levels checked. Ask your doctor or laboratory for the 25(OH)D test, also known as the 25-hydroxyvitamin D test. Please note that some labs do a similar test called 1-25(OH)D test, which is not as accurate a marker of your vitamin D status.
Most people should also strive to eat some foods that are naturally rich in vitamin D, such as:
Food Sources Serving Vitamin D (IU)
Wild salmon 3 ounces 530
Cod liver oil 1 teaspoon 400
Sardines, canned 3 ounces 231
Organic egg yolk 1 medium 25
For those that require supplementation I ask you to be very careful which brands you use. Vitamin D is fat soluble, and like many fat soluble nutrients, manufacturers use toxic chemical solvents to extract and separate the vitamin D. These solvents will leave residues in your vitamin D that you want to avoid. My favorite Vitamin D is D3 serum from Premier Research Labs. It is not manufactured with any toxic solvents and it contains a full 2200iu per drop. That makes it the cleanest and most cost effective vitamin D I have been able to find.
Be sure to have your Vitamin D levels checked at your next doctors visit.
If you require supplementation you should work with someone that is experienced in vitamin D supplementation to create a customized plan based on your specific needs.