coronary artery disease

Nature Reviews: Cardiology recently published an online review article looking at research on the link between vitamin D and blood pressure. Our bodies only produce adequate amounts of vitamin D if we get enough exposure to sunlight. UVB rays generate vitamin D in the skin and through a series of molecular processes, it circulates through the system. The darker your skin, the more UVB you need to produce the vitamin D you need.

The review authors look at 26 studies. Fifteen of them found an association between blood pressure and vitamin D levels. Basically, low vitamin D seems to be related to higher blood pressure. However, seven studies found no relationship while four noted that higher levels of vitamin D were associated with high blood pressure.

While the results of the studies are mixed, the authors show that all those with a large number of patients (from 4030 people up to 12,644 people) indicated that lower vitamin D levels are associated with higher blood pressure. The ones that show no relationship or higher blood pressure with higher vitamin D levels almost all had much smaller numbers of participants.

The review authors conclude that the weight of the evidence is growing that vitamin D is anti-hypertensive and that low vitamin D levels are connected to higher blood pressure. Obviously, with the mixed results, more and larger randomized studies are required to establish for sure if the relationship holds.

Two other related studies show links between low levels of vitamin D and cardiovascular outcomes. Researchers in Finland looked at records of 6219 people aged 30 years and over who had no diagnosed cardiovascular condition at the study baseline in 1978-1980. From the baseline to 2006, 640 people died from coronary artery disease (CAD) and another 293 from stroke. The researchers were able to show a statistical association between low vitamin D levels and the cases of stroke mortality but not for those of CAD.

Meanwhile, a group of clinical investigators from the Heart Institute of the Intermountain Healthcare system in Utah presented two studies on vitamin D at the American Heart Association meetings in Orlando. They found that vitamin D levels are a powerful indicator of heart disease and stroke. For over a year, the researchers followed 27,686 patients 50 years of age or older with no prior history of cardiovascular disease. People with very low levels of vitamin D were 45% more likely to develop coronary artery disease and 78% more likely to have a stroke than patients with normal levels. They also found that heart patients with low levels of vitamin D are more likely to be depressed than those who have adequate levels of the vitamin.