health guides

While evidence mounts that not getting enough vitamin D may contribute to a variety of negative health outcomes, one study suggests that getting too much vitamin D may also have adverse effects and that aiming for vitamin D levels that are neither too high nor too low could be optimal. Published in the Journal of Clinical Endocrinology & Metabolism, the study looked at data for 247, 574 men and women—the data included the participants’ vitamin D levels and information on which of them died in the ensuing years from heart disease, stroke, or heart attack. After analyzing the data, here’s what the researchers discovered:

• Having vitamin D levels of around 70 nmol/L was associated with the lowest risk of death from heart disease.
• Compared to those with vitamin D levels around 70 nmol/L, having vitamin D levels lower than 12.5 nmol/L was associated with a 2 times greater risk of death from heart disease. Yet, having vitamin D levels higher than 125 nmol/L was also associated with a 1.3 times greater risk of death from heart disease.
• The risk of death from stroke and heart attack followed similar patterns.

Nevertheless, there are a few important considerations to take into account when evaluating the findings of this study. First, the results are consistent with a large amount of other research showing that low levels of vitamin D may increase the risk of death, and the risk of some specific health conditions, such as bone fracture. Therefore, supplementing with moderate amounts of vitamin D (800–1000 IU per day) under the supervision of a doctor is generally a good strategy for most people. Second, the study was observational, and therefore can’t prove that the higher vitamin D levels actually contributed to the participants’ deaths from the cardiovascular events. It’s possible, for example, that people who tended to be sicker to begin with, or suspected that they were sick, simply took more vitamin D. Although researchers generally try to adjust their analysis to include factors such as illness, more research is needed to confirm the study findings.

Source: Journal of Clinical Endocrinology & Metabolism