MONDAY, Nov. 16, 2009 (Health.com) — People with heart disease and similar conditions who don’t have enough vitamin D are more likely to be depressed than their counterparts with adequate levels of the “sunshine vitamin,” according to a study presented at the annual meeting of the American Heart Association in Orlando. This link seems to be even stronger in the winter.
Vitamin D is called the sunshine vitamin because the human body produces it only when exposed to sunlight—although it takes just 10 to 15 minutes a day to make an adequate amount. Vitamin D, which helps the bones better absorb calcium, is also added to multivitamins and milk, and occurs naturally in fish.
A second study by the same team of researchers found that people age 50 or older who lack vitamin D are at a higher risk for heart disease and stroke, and are more likely to die earlier than people the same age who get adequate amounts of the vitamin.
These studies add to the mounting evidence about the dangers of vitamin D deficiency and may also shed light on the connection between depression and cardiovascular disease (which includes any disease caused by clogged arteries, including heart disease).
Depression and diseases of the arteries—both have been associated with vitamin D deficiency in the past—tend to occur together, says Heidi May, PhD, an epidemiologist with the Intermountain Medical Center at the University of Utah, in Murray, who participated in both studies.
“It is known that during the last century, the prevalence of depression has increased, and, more recently, that vitamin D deficiency has increased,” May says. “It is well-known that depression is associated with cardiovascular disease and events.” This research, she adds, “is trying to elucidate whether vitamin D deficiency is associated with depression and may be contributing to this increase in cardiovascular disease and events.”
In the first study, May and her colleagues measured blood levels of vitamin D in 8,680 people age 50 or older who had been diagnosed with heart disease, stroke, or another type of cardiovascular disease. Vitamin D levels above 30 nanograms per milliliter of blood (ng/mL) were considered normal, levels between 15 and 30 ng/mL were low, and those 15 ng/mL and below were deemed very low.
Among those with very low levels of vitamin D, 32% were depressed, as were 25% of the people with low levels, and 21% of those with normal levels. This trend was seen even among individuals with no history of depression.
Winter seemed to make the association even more pronounced. Seasonal depression, which typically occurs in winter, may be linked to lack of sunshine.
In the second study, which looked at 27,686 people age 50 or older with no history of cardiovascular disease, May and her colleagues found that, compared to individuals with normal levels of the vitamin, people with very low levels of vitamin D were 77% more likely to die, 45% more likely to develop heart disease, and 78% more likely to have a stroke during the study, which lasted for more than a year. They also had double the risk of heart failure.