A 65-year-old woman is seeing her cardiologist for follow up of an elevated heart artery calcium score on CT scan. They discuss various treatment options including starting a statin. She asks, “Should I continue to take my Vitamin D and calcium supplements since there is higher than normal calcium seen in my heart arteries?” How do vitamin D, calcium and their supplements affect the heart?
Vitamin D is necessary to maintain bone health and strength. Vitamin D is also an integral part of normal cell metabolism. Vitamin D receptors are present in almost every tissue in the body and vitamin D plays a role in regulating cell growth. Vitamin D is obtained by the body through 2 avenues: external sources (food and supplements) and internal sources (produced by the body). Vitamin D can be obtained from the diet (there are a few food sources that naturally contain vitamin D such as oily fish, liver, egg yolks, and vitamin D fortified milk) or by supplements. Vitamin D supplementation is becoming more and more widespread. Between 2011 and 2014, about 37% of the US population took a vitamin D supplement. In the same time period, 61% of adults over age 65 used a vitamin D supplement. Vitamin D can also be produced by the body. The skin turns ultraviolet rays from the sun into vitamin D (thus the name, “The Sunshine Vitamin”). The skin production of vitamin D depends on climate, skin pigmentation, sun exposure and age. Risk factors for low vitamin D levels include older age, colder climates, reduced outdoor activity, and sunscreen use.
Vitamin D levels in the blood can be measured. Vitamin D deficiency is defined as a vitamin D concentration of < 20 ng/ml. Levels of vitamin D between 20 and 29 ng/ml is considered insufficient. The optimal vitamin D level is > 30 ng/ml. Vitamin D deficiency can cause weak bones and fractures. It is associated with diabetes, autoimmune disorders and rheumatoid arthritis. Vitamin D deficiency can also cause heart problems by increasing inflammation, increasing blood pressure and causing arteries to stiffen. Studies have shown that low levels of vitamin D can increase the risk for heart artery disease, heart attack, stroke and congestive heart failure. Do vitamin D supplements mitigate the risk of low vitamin D levels? The effects of vitamin D on fractures and bone health is uncertain. A recent review showed that vitamin D supplementation does not prevent fractures or improve bone mineral density. In addition, well-designed trials show that vitamin D supplements do not benefit heart health. Lastly, vitamin D supplementation does not reduce the risk for cancer, stroke, high blood pressure or dying. Vitamin D supplementation is safe at levels up to 2000 IU/day, however at 4000 IU/day or more toxicity can occur. Vitamin D supplementation does not appear to be harmful to the heart, even at higher levels.
Calcium is the most abundant mineral in the body, with 99% of the body’s calcium stored in the bones and teeth. Adequate calcium intake is essential for bone development and maintenance. Because of their effects on bone health calcium and vitamin D are intricately intertwined. Like vitamin D, calcium can be obtained either in the diet or via supplementation (it is not naturally produced by the body). Food sources of calcium include leafy green vegetables, low-fat diary products, beans and almonds. The recommended dietary intake of calcium for adults 19 to 50 years old and men 51 to 70 years old is 1000 mg/day. For women 51 to 70 years old and for men and women older than 70 it is 1200 mg/day. Age, vitamin D and other factors influence calcium absorption by the body. People at risk for inadequate calcium intake include those with lactose intolerance and postmenopausal women. Calcium supplementation is very common with use by 40% of the general US population and more than 65% of postmenopausal women. Calcium supplementation does reduce the risk for bone fractures. Unfortunately, calcium supplements do appear to increase the risk for cardiovascular events, such as heart attack and stroke, especially at levels over 1400 mg/day. Calcium supplement users also had an increased risk for heart artery calcification compared to those not on supplements. Of note is the fact that higher intake of calcium in the diet was not associated with increased heart risks.
What are the recommendations for vitamin D and calcium as well as the use of their supplements? For the general population, obtain vitamin D from food sources and from sunlight. If vitamin D insufficiency persists despite diet and outdoor activity, then supplementation can be used. Calcium recommendations are similar; obtain calcium through the diet and increased physical activity. If calcium deficiency persists or there are increased needs, calcium supplements can be used, keeping in mind that there is a possibility of cardiovascular harm. For both vitamin D and calcium, pill-based supplements may not be better than a healthy life style, including a prudent diet and physical activity.
What should we tell our postmenopausal woman with an elevated coronary calcium score about her supplement use? There should be a frank risk/benefit, shared decision making conversation. Vitamin D supplements are neutral; they don’t seem to confer any benefit for heart health, but they are not harmful either. Calcium supplements help with bone health, but may come with added cardiac risks, including the possibility of worsening her coronary calcium. The supplements can cautiously continue as long as there is an understanding of the risks and benefits and with close monitoring.
