Many people don’t get enough sunshine on a regular basis putting them at risk for vitamin D deficiency. It is estimated that 40%-60% of the world’s population is deficient and some reports show that nearly 90% of American adults have Vitamin D deficiency. Most adults are believed to be somewhat deficient in Vitamin D but certain characteristics and conditions can put a person at even greater risk.
According to the National Health and Nutrition Examination Survey (NHANES), more than 90% of people with darker skin pigments (Blacks, Hispanics, and Asians) living in the United States now suffer from Vitamin D insufficiency, while 75% of the white population is deficient. People who suffer from Crohn’s disease or other inflammatory bowel diseases, people who have undergone gastric bypass surgery and people who have had removal of their gallbladders are also at greater risk of deficiency. Many doctors are starting to take this vitamin deficiency very seriously. Vitamin D is one of the most recommended supplements by physicians today and many doctors will order the 25-hydroxy vitamin D or 25 (OH) D panel for their patients upon request.
Vitamin D is actually a hormone because you can make it in your body using sunlight. Once it is made in the skin it goes to the liver and is converted to the circulating form which is what doctors measure- 25 hydroxy Vitamin D- then to the kidneys to its active form known as 125 dihydroxy Vitamin D. Without adequate sun exposure, your body is unable to make Vitamin D.
Vitamin D plays a critical role in regulating the immune system and a vitamin D deficiency has been linked to chronic illnesses including autoimmune disease and cancer. Vitamin D is critical in the human body from birth to death. Women of childbearing age in particular should be concerned about their levels. In utero, insufficient levels increase the risk of preeclampsia, one of the most serious complications of pregnancy. Deficiency also increases the risk of cesarean birth.
Vitamin D also has an impact on the fetus. Deficiencies are associated with wheezing disorders at birth, asthma and increased risk of dental carries later in life.
During the first years of life, vitamin D deficiency is associated with an increased risk of type 1 diabetes, Crohn’s disease, multiple sclerosis, rheumatoid arthritis and bone disease including osteomalacia. Osteomalacia is responsible for achiness in the bones, especially in the cold winter months.
In older adults, vitamin D deficiency increases the risk of colon cancer, breast cancer, type 2 diabetes, infectious disease, depression, Alzheimer’s and about a dozen other cancers.
Vitamin D has extremely important immuno-modulatory effects in the human body. Nearly every cell in the body has a receptor that can use it. It’s estimated that up to 2000 genes in the body are regulated directly or indirectly by Vitamin D. Vitamin D plays a role in cell growth to reduce malignancy. It has effects on immune cells that reduce the risk of TB infection, influenza infection, and autoimmune disease. The vitamin D receptor in the brain plays a major role in improving mood, altering neurotransmission, keeping brain cells healthy and reducing risk for dementia and neurocognitive dysfunction later in life.
There is good evidence that having adequate amounts of vitamin D does reduce risk for infectious diseases. School children in Japan who received 1200 IUs of vitamin D3 daily for 4 months during the winter reduced their risk of developing influenza infection by 42%.
In a study done at Yale, a vitamin D concentration ≥38 ng/ml approximately halved the risk for development of an acute viral respiratory tract infection over the observation period (p<0.0001).
How much Vitamin D do I need?
Many of my clients avoid direct sunlight for fear of skin cancer and premature aging, or lather on sunblock that prevents the body from making this critical nutrient. But, did you know that sunscreen with an SPF30 reduces the ability to make this important nutrient in your skin by about 97-98%?
I recommend to all of my clients that they should get 2000-3000 IU of vitamin D a day from a combination of dietary sources, sensible sun exposure and supplements. Children need 1000 IU a day. From my perspective there is no downside to increasing your intake to these recommended levels.
One of the most common myths that I hear is that excess vitamin D causes the liver to become toxic because it is fat soluble. The truth is that the liver has such a huge capacity to convert vitamin D to 25 hydroxy Vitamin D that usually you have to lose 80-90% of liver function before toxicity becomes an issue. In fact, absorption is a much bigger issue than toxicity. Absorption becomes an issue when a person suffers from Crohn’s disease or other inflammatory bowel diseases or when a person has undergone gastric bypass surgery or has removed their gallbladder. In these cases, higher doses of this nutrient are highly recommended. Another myth that many doctors and natural health websites are still circulating is that showering after skin exposure to the sun will wash off the chemicals needed to make vitamin D. We now know that production occurs in your living cells in the epidermis so it cannot be washed off.
Reference points for optimizing vitamin D in the body are as follows:
Minimum 30 ng/ml
Preferred range 40-60 ng/ml
Up to 100 ng/ml is perfectly safe
*Remember, toxicity is not an issue until your over 150 ng/ml and even then it would be unusual to have negative effects.
Vitamin D is found in only a few food sources including wild caught salmon, cod liver oil and mushrooms exposed to sunlight. Milk and orange juice are sometimes fortified with Vitamin D.
Studies have shown that taking 1000-2000 units of Vitamin D2 is as effective as taking 1000-2000 units of Vitamin D3 in raising and maintaining blood levels; therefore, both vitamin D2 and vitamin D3 are equally effective.
Maintaining a blood level of 25 hydroxy vitamin D is very important for overall health and wellness and the health of the body’s immune cells. I recommend following 3 easy steps to ensure that you are consistently maintaining adequate levels of Vitamin D.
Most experts recommend getting about 10-15 minutes daily of direct sunlight without sunscreen if you are fair to medium toned. If you have dark skin, you will likely need more time in the sun to make enough Vitamin D since your skin has more protection against the sun’s effects. If you are worried about the aging effects of the sun, put sunscreen on your face and chest, leaving your limbs exposed.
The best food sources are wild caught salmon, cod liver oil and mushrooms exposed to sunlight.
Dosaging recommendations from the Endocrine Society:
Neonates need 400 – 1000 units per day
Children need 600- 1000 units per day
Adults and Teens need 1500-3000 units a day
Obese people need two to three times more
I take 10,000 IU of vitamin D twice a week. That amounts to about 3,000 IU per day. The brand that I use is Metagenics.
**It can be ordered here:
References: Holick, M.F. Vitamin D Deficiency. New Engl. J. Med. 2007. 357:266-81
For more information, read The Vitamin D Solution by Michael Holick, PhD, MD
or go to Dr. Holick’s website at http://drholick.com
**I am not paid nor receive any compensation for my recommendations of products.