|Do You Get Enough Vitamin D?
Now that the long sunny days of summer are gone and winter is on the doorstep, it is even more important that you assess your vitamin D status. The health benefits to having sufficient vitamin D levels have permeated the media in recent years. We now know that nearly 85% of the US population are vitamin D deficient. We spend too many hours indoors and use tons of sunscreen when were are out in the sun. It certainly is prudent to use reasonable precautions about sun exposure but this vitamin D deficieny epidemic has put many of us at increased risk for many diseases, including osteoporosis, heart disease, obesity, insulin resistance, Alzheimere’s disease, arthritis, autoimmune diseases and cancers of the breast, colon, pancreas and prostate. A recent study also showed that individuals with chronic pain required significantly more pain killers and were treated 60% longer when their vitamin D levels were low compared to normal.
Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others, and available as a dietary supplement. It is also produced in the body when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D, also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyvitamin D, also known as calcitriol.
In supplements and fortified foods, vitamin D is available in two forms, D2 (ergocalciferol) and D3 (cholecalciferol). Vitamin D2 is manufactured by the UV irradiation of ergosterol in yeast, and vitamin D3 is manufactured by the irradiation of 7-dehydrocholesterol from lanolin and the chemical conversion of cholesterol. The two forms have traditionally been regarded as equivalent based on their ability to cure rickets, but evidence has been offered that they are metabolized differently. Vitamin D3 is more than three times as effective as vitamin D2 in raising serum 25(OH)D (active vitamin D) concentrations and maintaining those levels for a longer time, and its metabolites have superior affinity for vitamin D-binding proteins in plasma. Any supplements should preferentially contain vitamin D3 rather than the more common D2.
Vitamin D emerged as a protective factor in a prospective, cross-sectional study of 3,121 adults aged 50 years (96% men) who underwent a colonoscopy. The study found that 10% had at least one advanced cancerous lesion. Those with the highest vitamin D intakes (>645 IU/day) had a significantly lower risk of these lesions. More recently, a clinical trial focused on bone health in 1,179 postmenopausal women residing in rural Nebraska found that subjects supplemented daily with calcium (1,400-1,500 mg) and vitamin D3 (1,100 IU) had a significantly lower incidence of cancer over 4 years compared to women taking a placebo.
A recent meta-analysis found that use of vitamin D supplements was associated with a reduction in overall mortality from any cause by a statistically significant 7%. The subjects in these trials were primarily healthy, middle aged or elderly, and at high risk of fractures; they took 300-2,000 IU/day of vitamin D supplements.
“Vitamin D deficiency is associated with increased cardiovascular risk, above and beyond established cardiovascular risk factors,” said Thomas J. Wang, M.D., assistant professor of medicine at Harvard Medical School in Boston, Mass. “The higher risk associated with vitamin D deficiency was particularly evident among individuals with high blood pressure.”In a study of 1,739 offspring from Framingham Heart Study participants (average age 59, all Caucasian), researchers found that those with low blood levels of vitamin D had twice the risk of a cardiovascular event such as a heart attack, heart failure or stroke in the next five years compared to those with higher levels of vitamin D.
In a study previous cited in the October 2008 newsletter, and reported at the 2008 American Oncology Meeting, researchers retrospectively looked at more than 500 women over a period of 11 years. What they found was that those women who had been deficient in vitamin D at the time of their breast cancer diagnosis were 73% more likely to die from breast cancer than those with sufficient vitamin D at the time of diagnosis. In addition those that were deficient in vitamin D at the time of their diagnosis of breast cancer were almost twice as likely to have recurrence or spread over those years.
In a major epidemiological study by Cedric Garland PhD and others, the researchers exhaustively reviewed the medical literature on the relationship between breast cancer and vitamin D levels. According to the analysis done in this article, if women kept their vitamin D blood levels at approximately 52 ng/ml, we could expect a 50% reduction in the risk of breast cancer.
Many nutritional and vitamin D researchers recommend supplementing with 1000-2000 IU of vitamin D3 daily for most people. Current evidence suggests that the optimal blood level for vitamin D is between 60 to 80 ng/L ( the “normal” range is 30 to 100 ng/L).
Maybe it time to plan a winter vacation to a sunny destination. In the meantime, be sure to get a high quality vitamin D supplement and have your blood level checked; it could change your life.