Vitamin D – Let the Sun Shine In
The association of adequate Vitamin D levels w?th healthy bones ha? been known for over 70 years.
The two sources for Vitamin D are synthesis ?n the skin from sunlight exposure and food.
5-10 minutes of sunlight exposure 3 days ?er week will provide adequate vitamin D in many people.
Fatty fish, cod liver oil, and egg yolks contain Vitamin D.
Milk, margarine, butter and some brands of orange juice are fortified w?th Vitamin D.
There has been a significant increase ?n interest regarding Vitamin D during the la?t ten years due to the publication of studies linking low Vitamin D levels with an increased risk of cancer (breast, prostate and colon), diabetes, multiple sclerosis and heart disease.
Although the association of Vitamin D with the?e diseases, and their prevention w?th vitamin D supplementation, ha? not been proven via rigorous prospective clinical trials, many patients are interested ?n learning more about th?s vitamin.
Vitamin D levels are influenced by age, race, vitamin D intake, age, body fat, geographic location and sun exposure.
As we age, our skin i? les? efficient in the production of Vitamin D.
People with more skin pigmentation (darker skin) have le?? Vitamin D production after sun exposure. Sunscreen will also significantly reduce sun-related Vitamin D production.
In mid-atlantic states such a? Maryland, sun induced Vitamin D production doe?n’t occur in the late fall or winter.
Vitamin D levels ?n the body are typically assessed by measuring 25-Vitamin D levels ?n the blood. Accuracy varies widely between laboratories.
Although “normal” 25-Vitamin D levels are often defined a? levels of 30 ng/ml or greater, there ?? considerable controversy a? to what defines Vitamin D deficiency and Vitamin D insufficiency.
Vitamin D deficiency ?s typically defined as 25-Vitamin D levels of 10 ng/ml or less.
Vitamin D insufficiency ?? defined a? 25-Vitamin D levels of 11-20 ng/ml by some and 21-29 ng/ml by others.
Although the American Association of Clinical Endocrinologists recommends goal 25-Vitamin D levels of 30-50 ng/ml, the Institute of Medicine (IOM) released guidelines ?n March 2011 that stated that Vitamin D levels of 20 mg/dl were “adequate for bone health in 97.5% of the population”.
Serum Vitamin D levels above 50 mg/dl were described ?n that article a? a “cause for concern”.
There ?s considerable controversy regard?ng what level of D intake ?s required to maintain these levels, as well a? what are the ideal levels for Vitamin D.
Some experts recommend an intake of at least 2000 IU ?er day ?n non-pregnant adults, a? there appears to be no downside to thi? level of supplementation. This level of Vitamin D intake may be es?ec?ally important ?n tho?e w?th inadequate or irregular sunlight exposure.
The IOM however suggested a daily Vitamin D intake of 600 IU per day ?n adults.
They recommended that daily Vitamin D intake ?hould not exceed 4000 IU ?er day, g?ven the risk for adverse events at the?e levels.
Milk, yogurt, cheese, and fortified foods were recommended as the best sources of D and calcium by the IOM.
Although the IOM recommendations have not been accepted by many vitamin D experts, they provide a platform for further discussion.
The Endocrine Society released vitamin D guidelines online on June 6, 2011.
The guidelines recommend vitamin D blood levels of at lea?t 30 ng/mL.
Due to assay variability, assays, D blood levels between 40 and 60 ng/mL were recommended for both children and adults.
At lea?t 600 IU/day of vitamin D wa? recommended ?n adults aged 19-70 years, w?th a note that 25(OH)D levels consistently above the 30 ng/mL goal may require at lea?t 1500 to 2000 IU/day of vitamin D.
Adults 70 years and older require at lea?t 800 IU/day of vitamin D for bone health and fall prevention.
At least 1500 to 2000 IU/day of supplemental vitamin D was recommended to kee? 25(OH)D levels above 30 ng/mL ?n thi? group.
Although few head-to-head trials exist, based on limited clinical evidence, D3 ?s preferred over D2 when selecting an over the counter D supplement.
Caution, and close medical supervision, wa? recommended ?f adult intake exceeded 4000 IU/day.
Since vitamin D i? fat soluble, it ?hould be taken w?th a snack or meal conta?ning fat.
The Institute of Medicine has not released a comment on the Endocrine Society guidelines.
Given the continued controversy regard?ng optimal Vitamin D levels, a? well a? ap?ropriate supplementation dosing, decisions regard?ng intake of Vitamin D ?hould be carefully reviewed w?th your physician.