Ask The Doctors: March 2018
Q: Is vitamin D good for the heart? If so, how much should I take?
A: Many adults have low levels of vitamin D (vit D). Obesity, dark skin, low sun exposure, female gender and age contribute. In addition to strengthening bones, vit D is touted to prevent diabetes and regulate blood pressure, inflammation and vascular smooth muscle—all of which may help reduce heart disease. One study reported a 64 percent higher risk of heart attack in adults with the lowest levels of vit D (less than 15 ng/ml), compared to those with the highest (more than 50 ng/ml).
Although the association between vit D levels and heart health is biologically plausible, it is unclear whether supplements reduce risk. A 2011 meta-analysis found vit D had no effect on heart attack. In a study of older women, low daily doses of vit D did not reduce heart disease. A 2017 trial showed no benefit from high monthly doses over three years. Also, too much vit D may lead to high blood calcium levels, which may cause constipation, kidney stones or abnormal heart rhythms. A 2015 study found that too much and too little vit D increased the risk of death. Four randomized trials now underway may provide more insight on this subject.
The Institute of Medicine suggests adults aged 51 to 70 take 400 IU of vit D a day and those over 70 take 600 IU for bone health. Some doctors are now recommending 1,000-2,000 IU. The safest way to get vit D is through food, but there are few sources (salmon, tuna, fortified cereals and milk). Sunlight is the best natural source. If you take over-the-counter supplements, vit D3 is best, because it is absorbed well.
Should you take vit D specifically for heart health? Until further research defining heart benefits is available, you would be prudent not to take it unless your doctor determines your vit D level is low and you would benefit. On a blood test, a 25-hydroxyvitamin D level should generally be 30-60 ng/ml.
Q: Should I take calcium supplements for my bones? Can it harm my heart?
A: An estimated 43 percent of the US adult population and 70 percent of older women take calcium supplements. However, studies have raised questions about a possible link to heart disease. One concern is that excess calcium might build up in heart arteries and contribute to atherosclerosis. New Zealand researchers pooled the results of 11 trials examining effects of calcium on osteoporosis or colon cancer and found that more people taking calcium had heart attacks, strokes or died suddenly than those taking placebo. Studies from the Women’s Health Initiative have also raised concern. An intake of more than 1,400 mg/day of calcium has been associated with higher rate of death from all causes. However, a direct relationship between total calcium intake and heart disease has not been well established.
How you get your calcium may be important. In 2016 a 10-year study concluded that calcium supplements increased coronary calcifications by 22 percent, although a diet high in calcium-rich foods (more than 1,022 mg per day) appeared to be protective. At the same time, the National Osteoporosis Foundation found that evidence did not support a connection between calcium intake (particularly from foods) and heart disease. To further complicate things, a recent meta-analysis of studies of adults over age 50 found that vit D and calcium supplements did not seem to reduce bone fractures.
The Institute of Medicine recommends 1,000 mg of calcium daily for younger adults and up to 1,200 per day for women over 50 and men over 70. Calcium from food (such as milk, cheese, tofu, yogurt and fortified juice) is best. Turn to supplements only if there’s a shortfall in your diet or other medical need, and keep your total intake below 2,000-2,500 mg a day. Talk to your doctor before using calcium supplements.