As a native Californian, I have grown up worshiping the sun, and really, who doesn’t? The star to which we owe our very existence and worshiped in ancient cultures. The Egyptian pharaoh preceding Tutankhamun even banned the worship of any other god BUT Aten, the sun disk, and renamed himself “AkhenATEN”. Providing more than just warmth and great beach days, the sun allows the occurrence of certain essential biochemical processes, such as photosynthesis and the production of vitamin D.
Vitamin D is a lipid soluble vitamin that can be obtained through dietary means, or through sun exposure. UV-B rays penetrating the skin catalyze the production of a pre-cursor to vitamin D, which then must travel to the liver then the kidneys for activation. Maintaining adequate vitamin D levels has been associated with decreased risks of breast and colorectal cancers, psychiatric disorders, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes. Vitamin D inhibits renin production in the kidneys, has immunomodulatory effects on lymphocytes, and increases the absorption of calcium in the gut.
Most people immediately think of bones when calcium comes to mind. However, calcium is an essential element in many biological processes, such as muscle contraction and heart conduction. As a result, it is essential that levels of calcium within the blood are maintained within a specific range. High levels of calcium results in excessive thirst, and can eventually cause lethargy, muscle weakness, and heart rhythm changes. Low levels may result in stiff aching muscles and confusion.
Under non-pathological conditions, excess serum calcium is moved into the bones out of the circulation and low circulating calcium causes calcium leaching from the bones through signaling from parathyroid hormone and calcitonin. Long term leaching of calcium from the bones to maintain adequate concentrations of calcium in the blood stream eventually leads to osteopenia and osteoporosis. Vitamin D also helps to increase absorption of calcium.
In July 2010, the Boston Medical Journal published the shocking results of a meta-analysis by Bolland et al. The final analysis compiled data from 11 double blind randomized control trials where subjects took calcium without vitamin D compared to placebo. The trial showed a statistically significant increase in heart attacks for patients supplemental calcium (HR 1.31, p0.035), although no statistically significant increase in risk of death.
Further analysis showed that the risk was increased only when daily intake was above 805 mg/day of calcium, which is still only a moderate dose. Rather than proving that calcium supplementation is bad, this study demonstrates the importance of vitamin D, which had been excluded from the study due to previous analyses showing decreased mortality with vitamin D supplementation with calcium.
In response to patient concerns that calcium supplementation will increase their risk of myocardial infarction (aka heart attack or MI), I would suggest that patients taking calcium supplements ensure that they are getting adequate vitamin D from the sun, dietary intake or supplements. Further studies and analyses are needed to show specifically what recommendations health care providers can make to keep patients safe as well as to fully understand the reason for increased risk of MI.
Vitamin D supplementation has become the latest hot topic; as such there is a variety of literature covering many different benefits it may provide. For the sake of time and entry length, I will cover one more article published in July 2010 in AIDS.
Previous literature reported high rates of vitamin D deficiency in patients living with HIV/AIDS, so Welz and colleagues set out to examine potential risk factors in HIV positive patients. Results of the study indicated that the winter season (when patients are exposed to less sun), black ethnicity (a patient population that needs longer sun exposure to produce adequate vitamin D), CD4 count nadir of less than 200 cells/mcL, and a medication regimen containing efavirenz were associated with vitamin D deficiency. Age, sex, renal function, and other anti-retroviral medications were not associated with increased risk.
Efavirenz is a non-nucleoside reverse transcriptase inhibitor recommended in combination with two medications from the NRTI class as one of the first line regimens for treatment-naïve patients with HIV. It is a component of the first ever one pill a day anti-retroviral regimens and is not associated with fat redistribution, as seen with the buffalo hump formation after use of protease inhibitors.
This trial indicates that it may be beneficial for patients taking efavirenz to take moderate daily supplementation of vitamin D to avoid long-term complications of vitamin D deficiency and for cardiovascular protection.
Akhenaten may have not known about the existence or biochemical significance of vitamin D, he was most certainly correct in proclaiming the sun the most important “god” for ensuring life on earth.
References:
Mayo Clinic electronic resource. http://www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind accessed 8/12/2010.
The Merck Manuals: online medical library. http://www.merck.com/mmhe/sec12/ch155/ch155b.html accessed 8/12/2010.
Booth M. The secret history of the world. The Overlook Press NY; 2008.
Holick MF et al. Vitamin D deficiency: a worldwide problem with health consequences. American Journal of Clinical Nutrition 2008;87(4):1080S-6S.
Bolland MJ et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ 2010;341:c3691.
Welz T et al. Efavirenz is associated with severe vitamin D deficiency and increased alkaline phosphatase. AIDS 2010;24(12):1923-1928
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