Tuesday, March 16, 2010

Do You Need More Vitamin D?

By Dr. Jennifer Morganti

Vitamin D has been the topic of the most exciting news in the scientific community for the past several years. Numerous clinical trials reveal that a large portion of the North American population is quite deficient in this critical nutrient, and this may be a key reason so many suffer with one or more inflammatory-based conditions.

It is common knowledge that vitamin D enhances absorption of calcium from the intestine to promote bone building, thus preventing osteoporosis. The latest research, however, has greatly expanded scientists' understanding of vitamin D. A vitamin D deficiency has been linked with several health problems, including inflammation, depression, seasonal affective disorder (SAD), nervous system problems, Rheumatoid arthritis, inflammatory bowel disease, cancer, cardiovascular disease, and musculoskeletal pain. Vitamin D's anti-inflammatory activity seems to be one of the underlying mechanisms that make it so effective at alleviating these conditions.

Vitamins D2 and D3 are the primary forms, both of which are eventually converted via the liver and kidneys to the more bioactive form, calcitriol. Vitamin D3, also known as cholecalciferol, can be obtained from food (animal sources), supplements, and from sun exposure, which is then converted to a usable form by cells in the skin. The pervasive use of sunscreen has likely contributed to high deficiency rates, as it blocks the absorption of UV light and vitamin D conversion. D2 (ergocalciferol) is derived from fungal or plant sources and less efficient at converting to usable calcitriol than D3. Some sources claim that D2 absorption is one third of the rate of D3 absorption. Vitamin D2 is also made synthetically, but this form can be toxic and should be avoided entirely. A wide range of the body's tissues have vitamin D receptors and, like the kidneys, have the ability to convert preliminary forms of vitamin D to calcitriol. This indicates that this nutrient is critical to these tissues' metabolic processes.

Because sunlight exposure is such a critical source of vitamin D3, there is a correlation between living in northern latitudes and vitamin D deficiency. Subsequently, this population has increased risks of at least two maladies: cardiovascular disease and Multiple Sclerosis (MS). One study shows that patients with cardiovascular disease have lower levels of vitamin D than healthy people. Another demonstrates that patients with hypertension reduced their blood pressure significantly simply by increasing vitamin D levels via increased exposure to ultraviolet light. Vitamin D also has been shown to reduce C-reactive protein (CRP) levels, a marker for inflammation and an indicator of increased risk for heart disease.

MS is a neurological disease that exhibits symptoms of fatigue, muscle weakness, vision problems, loss of balance and muscle coordination, slurred speech, tremors, stiffness, and bladder problems to name a few. MS is also believed to have an autoimmune component. Incidences of MS are elevated in northern latitudes because of the limited availability of sunshine. The connection between MS and vitamin D levels was finally given credibility in 2006 when the Journal of the American Medical Association announced that MS risk can be lowered by increasing vitamin D based on a large amount of epidemiological data gathered between 1992 and 2004. These researchers felt that vitamin D may prevent MS because it is a potent immune modulator and because of its ability to temper MS's autoimmune component. An additional clinical trial shows that daily supplementation with 5000 IU of vitamin D3 (plus calcium and magnesium) over two years reduced exacerbations of MS symptoms.

A multitude of studies also conclude that low vitamin D levels are linked with increased risk of cancer, such as breast, ovary, colon, and prostate, while many in vitro (laboratory-based), animal, and human studies show that vitamin D prevents cancer cells from proliferating. At the 2007 annual meeting of the conservative American Association for Cancer Research, the CEO of Roswell Park Cancer Institute confirmed that a significant amount of research strongly links low vitamin D levels with increased risk of many types of cancers.

Vitamin D levels can be measured by a simple blood test, which may be called either 25(OH)D or 25-hydroxyvitamin. Be aware that some labs have not yet updated their reference ranges, and that the ideal levels of vitamin D are now considered to be over 50 ng/mL versus 20-45 ng/mL as some labs may indicate. An article in the June 2007 edition of The New England Journal of Medicine describes how a leading researcher on vitamin D, Dr. Michael Holick, called for a fourfold increase in the recommended daily intake (RDI) of D3 from 200 IU to 1000 IU daily. Other physicians call for even higher doses, such as 2000-4000 IU. Holick also called for an increase in the current tolerable maximum daily dosage from 2000 IU to 10,000 IU daily. To raise vitamin D levels, it is wise to take at least 1000 IU daily for 4 to 8 months before levels return to normal. (Note: Vitamin D toxicity is now thought by some to occur only when taking over 100,000 IU daily for several months.)

Did you take your vitamin D today?

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