If your doctor told you to take vitamin D, you’re not alone. In recent years, many doctors have jumped on the bandwagon, prescribing high doses of vitamin D.
Yet, while your heart needs vitamin D, there’s a “sweet spot.” Taking too much vitamin D can cause as much harm as taking too little—increasing your risk of stroke and other cardiovascular issues.
How Does Vitamin D Help Your Heart?
Numerous studies have linked low blood levels of vitamin D with increased arterial stiffness and endothelial dysfunction, fatal strokes, and even higher risk of fatal cancer among patients with cardiovascular disease.
One of the largest studies was conducted by researchers at Copenhagen University Hospital and the University of Copenhagen. They reviewed data from studies of more than 10,000 Danes and compared those with the lowest levels of vitamin D (less than 15 ng/mL) to those with the highest levels (more than 50 ng/mL).
They discovered that those with low levels of vitamin D (versus the optimal level) were 64% more likely to have a heart attack. Plus, they had a 40% higher risk of ischemic heart disease, a 57% increased risk of early death, and an 81% higher risk of dying from heart disease.
Plus, a 2018 study published in the International Journal of Nanomedicine suggests that the D3 form of vitamin D helps to repair damage to the delicate endothelial lining of your blood vessels caused by heart disease. And it helps to and helps to trigger the production of nitric oxide which is important for healthy blood flow.
Too Much Vitamin D Can Be Just as Harmful
Research released in 2015 by the University of Copenhagen found that taking too much vitamin D can be as risky as having a vitamin D deficit. For their study published in the Journal of Clinical Endocrinology and Metabolism, researchers followed participants in the chronic obstructive pulmonary disease (COPD) study, which monitored 250,000 people from 2004 to 2011.
What they discovered is a J-shaped curve of mortality—which means people with too much, or too little, vitamin D in their bloodstream had a higher rate of mortality.
Deaths from a stroke or other cardiovascular event doubled when blood levels of vitamin D fell below 50 nmol/L. Deaths also increased by one-third when vitamin D levels in the blood rose to over 100 nmol/L. The ideal blood level of vitamin D was roughly between 50 to 100, with 70 nmol/L being the optimal level.
But while I agree with their findings, there’s a missing piece to this study—we don’t know if the research participants were also taking calcium supplements. This is an important detail because calcium supplements taken with high dose vitamin D can create coronary calcifications that can lead to cardiovascular disease.
How Much Vitamin D Should You Take?
Many people assume they’re getting enough vitamin D through their diet or through the synthesis of sunlight by the skin. Yet, vitamin D deficiency is still a widespread problem.
How much vitamin D should you take? The minimum recommended daily intake is 1,000-3,000 IU daily if you are healthy. It’s also prudent to check your vitamin D level at least once a year to make sure you are in that sweet spot and getting all the benefit and none of the harm. If your vitamin D levels are low, you can take 5,000 to 10,000 IU a day for up to three months and recheck your levels.
If you have vitamin D levels that are abnormally high or low, seeing an endocrinologist may be the best way to help stabilize your levels.
Which Form of Vitamin D Should You Take?
Vitamin D2 is found in some foods and a lot of multivitamin formulas. But it’s less active than D3, which is the form of vitamin D your skin manufactures with exposure to UV light (sunshine). So, I prefer vitamin D3.
However, there’s one note of caution. People with adenoma of the parathyroid gland, granulomatous diseases, lymphoma, sarcoidosis, and tuberculosis need to be careful about taking vitamin D. That’s because people with these conditions often produce too much vitamin D, so you want to work closely with your doctor. But, in general, many of us do not get enough vitamin D.
• Peter B. et al. Journal on Arteriosclerosis, Thrombosis and Vascular Biology 2012
• Durup D. et al. Journal of Endocrinology and Metabolism 2015