Low Vitamin D Raises Heart Disease Risk
It appears sunshine is really good for your heart, or at least when it helps make vitamin D for your body. Researchers in Copenhagen report that people who have low levels of vitamin D are at significantly higher risk of ischemic heart disease and early death, but you can take steps to reduce that risk.
Vitamin D is near and dear to your heart
It's been well publicized in numerous studies that vitamin D is necessary for strong bones, but research concerning its impact on heart health is not as common. This new research, conducted by experts at the University of Copenhagen and Copenhagen University Hospital, involved 10,170 men and women who did not consume vitamin D-fortified foods and who were followed up for 29 years.
Researchers considered the participants' level of plasma 25-hydroxyvitamin D, which is also known as calcidiol. Calcidiol is a prehormone that is produced in the liver and is the body's main storage form of vitamin D and also the form referred to when considering an individual's vitamin D levels.
The blood samples considered were drawn between 1981 and 1983. During the follow-up period, 3,100 adults developed ischemic heart disease (e.g., coronary artery disease), 1,625 developed myocardial infarction (heart attack), and 6,747 died. Analysis and comparison of vitamin D levels with the risk of these events revealed that low levels of vitamin D (less than 15 nm/L [nanomoles per liter] compared with optimal levels (more than 50 nm/L) were associated with a
- 40% higher risk of ischemic heart disease
- 64% higher risk of heart attack (myocardial infarction)
- 57% higher risk of early death
- 81% higher risk of fatal ischemic heart disease or heart attack
In addition, the investigators found that low levels of vitamin D associated with increased risk of ischemic heart disease and early death were independent of levels of vitamin D fortification in foods.
In Denmark, the recommended level of vitamin D is at least 50 nm/L, while in the United States, most doctors consider 75 nm/L (equal to 30 ng/mL [nanograms per milliliter]) to be sufficient. The Vitamin D Council, a nonprofit center for evidence-based research on vitamin D, also suggests people keep their vitamin D level around 50 ng/mL.
How to reduce your risk of heart disease
According to Borge Nordestgaard, clinical professor at the Faculty of Health and Medical Sciences, University of Copenhagen and senior physician at Copenhagen University Hospital, the study shows "a strong statistical correlation between a low level of vitamin D and high risk of heart disease and early death."
What is uncertain is whether a low vitamin D directly leads to heart disease and early death or if vitamin deficiency is an indicator for poor overall health. In either case, you can improve your vitamin D levels by exposing your unprotected skin to direct sunlight for about 15 to 20 minutes per day three to four days per week. (Be sure to apply sunscreen following this exposure.)
Few foods are rich in vitamin D, but they should be included in your diet as well. They include certain fish (e.g., salmon, herring, halibut, catfish, oysters) and fortified soy beverages, cow's milk, and cereals. Vitamin D supplements are also available, but according to Nordestgaard, "it has not been proven that vitamin D as a dietary supplement prevents heart disease and death."
Brondum-Jacobsen P et al. 25-Hydroxyvitamin D levels and risk of ischemic heart disease, myocardial infarction, and early death: population-based study and meta-analyses of 18 and 17 studies. Arteriosclerosis, Thrombosis, & Vascular Biology 2012 Nov; 32
University of Copenhagen
Vitamin D Council