As a cardiologist and researcher at the Johns Hopkins University School of Medicine, Dr. Erin Michos is busy—so she wakes up extra early to fit in her 5 a.m. jog. As a cardiologist and researcher at the Johns Hopkins University School of Medicine, Dr. Erin Michos is busy—so she wakes up extra early to fit in her 5 a.m. jog.
Running is certainly good for her health, but there is a flaw in Michos’ workout regimen. After a routine checkup with her doctor, Michos discovered that she had low vitamin D levels. Since she often jogs before the sun comes out, she likely wasn’t absorbing the sunlight needed to create vitamin D during her time outside. As a physician, Michos knew all too well what being low on vitamin D, the “sunshine vitamin,” could mean for her health. People get vitamin D by spending time in the sun (the skin makes vitamin D due to UV exposure) or by eating foods such as fortified dairy products, egg yolks or fatty fish.
Researchers have known for years that vitamin D deficiency can cause bone weakness, since the vitamin helps the body absorb calcium and phosphorous, two minerals critical for bone health. But recently, scientists have also been looking into whether vitamin D, which acts as a hormone in the body, may also be implicated in a wide range of other health problems, including strokes, multiple sclerosis, muscle weakness—and Michos’ area of research: heart disease.
Michos is certainly not alone in lacking vitamin D. These days, the deficiency is very common in all age groups. “Essentially everyone is at risk,” notes the Endocrine Society. There are multiple reasons: People are spending less time outside in the sun—and wearing sunscreen when they do go out. They are eating fewer vitamin D-fortified foods. And the rising rate of obesity is also partially to blame, since vitamin D can be absorbed by fat.And so, after realizing that she was one of many vitamin D-deficient Americans, Michos started taking a vitamin D supplement last year.
To be clear, Michos says she took her supplement for bone health; research hasn’t yet definitively demonstrated whether vitamin D causes the litany of other diseases it could be linked to.
But bone health is an adequate reason to be concerned about vitamin D levels, says Dr. Gary Applebaum, who practices at Sinai Hospital in Baltimore. A gerontologist, he notes, “Vitamin D deficiency is very common amongst seniors; it’s somewhat of an epidemic.” Because of the long-term effects of vitamin D on bone health and growth, pediatricians are particularly attuned to monitoring children’s vitamin D levels.
“I see vitamin D deficiency relatively frequently,” says Dr. Ashanti Woods, who practices at Mercy Medical Center in Baltimore. “Parents should be concerned about their child’s vitamin D intake, particularly if they’re concerned about their child’s growth.”
In fact, Woods says that the deficiency is so common that he usually doesn’t even need to order a blood test to confirm it. “It is generally safe to assume your child or young adult who enjoys fast food, video games and movies is vitamin D-deficient and no blood work is needed,” he says.
In response to this growing problem, the American Academy of Pediatrics updated the amount of vitamin D it recommends a few years ago. Infants under 12 months of age that are breast-fed should be given daily supplement drops that provide 400 IU (international units) of the vitamin, and those that are bottle-fed should drink formula with the vitamin included. Older children and adolescents should receive a daily dose of 600 IU.
Aside from the elderly and children, people of certain ethnicities are also at greater risk for deficiency. Specifically, people with darker skin have more trouble making vitamin D from sunlight exposure alone, and so studies have found that African-Americans and Latinos have significantly higher rates of deficiency.
Possible Links to M.S.In the past few years, scientists have grown increasingly interested in exploring possible connections between vitamin D deficiency and various diseases. As a hormone, vitamin D helps to regulate more than 200 genes, according to Johns Hopkins University.
“Vitamin D affects almost every cell in the body,” says Dr. Lawrence Appel, director of the Welch Center for Prevention, Epidemiology and Clinical Research at Johns Hopkins. Appel is seeking participants for a large study that will examine the possible link between vitamin D deficiency and falls among the elderly. His work builds on some “promising studies,” he says, suggesting a causal link. The work is far from straightforward, however, because while some studies suggest a benefit from vitamin D, other studies have shown no effect and a few have even suggested harm from high levels of vitamin D (supplements in the multiple thousands of international units).
While Appel says he doesn’t recommend that elderly patients take vitamin D supplements specifically to reduce the risk of falls, he does recommend that they monitor their levels of the vitamin to assure bone strength. Another researcher at Johns Hopkins, neurologist Dr. Ellen Mowry, is exploring whether vitamin D affects multiple sclerosis.
According to some research, MS is rarer close to the equator and relatively common in northern Europe and the Southern Hemisphere. Since vitamin D is generated when skin is exposed to sunlight, low levels of the vitamin could be one factor in the disease. While there is “compelling” evidence that people who develop M.S. are more likely to have lower vitamin D levels, says Mowry, “we certainly can’t be sure the associations between vitamin D and M.S. risk or prognosis are causal.” Ultraviolet light from the sun may have its own immune properties, so the studies that show a higher vitamin D level is protective may relate to a benefit of UV light or other activities that tend to lead to more sun exposure such as outdoor exercise.
In a current study, Mowry is trying to determine whether high-dose vitamin D supplements can reduce the number of relapses in M.S. or decrease the number of new “spots” in the brains of people with the disease. Ultimately, Mowry tries to make a joint decision about vitamin D supplementation with her patients. “I discuss the pros and the gaps in knowledge about the role of vitamin D supplements with them,” she say. “Many patients end up taking supplements, but I always remind them that we might be wrong. It may not help—or in theory it could be harmful.”
Michos is similarly cautious. She is finding that low levels of vitamin D appear in people who have various negative health outcomes in relation to heart disease and other problems. But she isn’t prepared to say that vitamin D deficiency is actually the cause of these negative health outcomes. Low vitamin D levels may be a marker of sunlight exposure and other lifestyle factors, and these factors might have health effects entirely separate from vitamin D.
Increasing Your Intake
Before considering supplementation, Michos and other doctors recommend first focusing on natural ways of acquiring the sunshine vitamin. Sunlight is by far the most efficient way to take in vitamin D: Spending 15 minutes outside during peak summer sunlight (without sunscreen) can give your body 30 times the amount of vitamin D as 8 ounces of fortified milk, she notes.Of course, too much time in the sun without sunscreen can increase your risk for skin cancer. Michos’ approach is to wear sunscreen on her face but not on her arms when she spends brief periods of time outside. However, she avoids longer periods of direct sun exposure and wears sunscreen and protective clothing. Woods, the pediatrician, also recommends getting kids outdoors on sunny days; drinking milk fortified with vitamin D; eating egg yolks and fatty fishes; and ensuring a healthy weight.
“Fortunately, appropriate [vitamin D] intake can be accomplished for most children through regular outdoor play, a well-balanced diet and perhaps a multivitamin if needed,” Woods says. “Parents should encourage a well-rounded diet that addresses all the food groups. If their child is picky, parents should consider a multivitamin with vitamin D.”
Geriatricians caution that elderly people in nursing homes are at a very high risk of developing vitamin D deficiency. This can be dangerous, especially because older people are more likely to experience bone fracture. The National Institutes of Health recommends people ages 51 to 70 receive at least 600 IUs of vitamin D daily, and people 71 and older receive 800 IUs. It is possible to get too much vitamin D, and for this reason, the doctors interviewed for this article don’t recommend taking doses in the multiple thousands of IUs unless a patient is under medical supervision.
“More isn’t necessarily better,” says Michos, noting that if you already have a healthy amount of vitamin D, there is no benefit to increasing your intake. As for her own vitamin D regimen, Michos says she isn’t the “biggest fan” of multivitamins in general because of the lack of evidence that they produce positive health outcomes. So she’s stopped taking her own vitamin D supplement this spring and summer, when she is getting more sunlight. If her levels fall again in the winter, however, she may begin taking the supplement again.