Vitamin D is making headlines again. A recent report in the Archives of Internal Medicine found that lower blood levels of vitamin D are associated with an increased risk of cardiovascular-related death and death overall.
According to a current panel, some 50 to 60 percent of older people in North America and around the world suffer from a vitamin D deficiency. It has also been found that younger individuals face a similar scenario. This causes a great deal of concern because falls, fractures, cancer, immune system dysfunction, cardiovascular disease, and hypertension have been linked to vitamin D blood levels (as measured by 25-hydroxyvitamin D) lower than 20 to 30 nanograms per milliliter. However, a compound called 1,25-dihydroxyvitamin D is thought to mediate these effects, and it is created by the body as well as converted from 25-hydroxyvitamin D.
The new findings come from research performed by Harald Dobnig, M.D. (Medical University of Graz, Austria) and colleagues. They recorded 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels in 3,258 consecutive patients who were about 62 years old, on average. The patients went to a single medical center between 1997 and 2000 for coronary angiography testing, and then they were followed up for about 7.7 years.
During follow-up, 22.6% (737 patients) died – 62.8% (463) of these for cardiovascular-related reasons. Patients in the lower half of 25-hydroxyvitamin D levels and the lowest quarter of 1,25-dihydroxyvitamin D levels had higher overall death rates and higher death rates from cardiovascular causes. The researchers noticed the same effects even after statistically controlling for factors such as coronary artery disease, physical activity level, and co-occurring diseases.
Dobnig and colleagues also found that the low 25-hydroxyvitamin D levels corresponded with inflammation markers (like C-reactive protein, which is linked to heart failure) and damage to cells that is oxidative, or oxygen-related.
The researchers clarify that, “Apart from the proved effects that vitamin D has on bone metabolism and neuromuscular function, appropriate serum levels (that may also be higher than in the present investigation) are associated with a decrease in mortality.” They add that even though it has not been proved, “It seems possible that at least part of this effect may be due to lowering of a risk profile promoting atherosclerosis [narrowing of the arteries] and preventing cardiovascular end points.”
“Based on the findings of this study, a serum 25-hydroxyvitamin D level of 20 nanograms per milliliter or higher may be advised for maintaining general health,” conclude the authors.
Independent Association of Low Serum 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D Levels With All-Cause and Cardiovascular Mortality
Harald Dobnig; Stefan Pilz; Hubert Scharnagl; Wilfried Renner; Ursula Seelhorst; Britta Wellnitz; Jürgen Kinkeldei; Bernhard O. Boehm; Gisela Weihrauch; Winfried Maerz
Archives of Internal Medicine (2008). 168[12]: pp. 1340 – 1349.
Written by: Peter M Crosta