Want to avoid a heart attack or stroke ? In addition to well-known risk factors like diet and exercise , you may want to keep an eye on your vitamin D levels too . Small amounts of vitamin D is available in food , such as fish , cod liver oil , and fortified milk and juice . Low levels of the `` sunshine vitamin '' -- so nicknamed because we get most of our vitamin D from sunlight -- may increase the risk of cardiovascular disease , according to a report published Monday in the Journal of the American College of Cardiology . About 30 to 50 pecent of American children and adults do n't get enough vitamin D , says coauthor James O'Keefe , M.D. , cardiologist and director of preventative cardiology at the Mid America Heart Institute , in Kansas City , Missouri . `` Society has been slow to respond to the pleas of vitamin D experts for years , '' O'Keefe says . `` People say , 'Well , I go outside , ' but the truth is we just are n't outside enough -- or when we are , we 're using sunscreen or wearing protective clothing . '' Small amounts of vitamin D can be consumed through food , such as fish , cod liver oil , and fortified milk and juice . But to achieve the daily 1,000 to 2,000 international units ( IUs ) that most people need , a dietary supplement is almost always necessary , according to the report . Oral doses of up to 2,000 IUs a day are considered safe and are available over the counter . Watch more on vitamin D recommendations for children » . People with vitamin D levels below 15 nanograms per milliliter ( deficiency is defined as less than 20 ng/ml ) are twice as likely to have a heart attack , stroke , or other cardiovascular event within the next five years as those with higher levels , according to the Framingham Heart Study , a large , ongoing study of heart risk factors . Because the Framingham Heart Study is not a randomized controlled trial , it 's still not clear if vitamin D is the real reason for the link ( the vitamin 's levels could drop in unhealthy people for other reasons ) , or if taking a supplement would lower the risk . However , experts agree that a connection is likely . Vitamin D appears to regulate insulin production in the pancreas , and a deficiency could raise diabetes risk . Low levels of vitamin D can also raise blood pressure and increase inflammation in the arteries , `` a recipe for disaster , '' says O'Keefe . `` These are the fundamental disturbances that predispose us to blood clots , strokes , and cardiac deaths , '' he says . Susan Harris , D.Sc. , an epidemiologist in the Bone Metabolism Laboratory at Tufts University in Boston , Massachusetts , agrees that there 's little harm in assuming that vitamin D may help the heart . `` It looks like vitamin D is important in very basic physiological functions like appropriate immune responses and inflammation , which play a role in cardiovascular disease and other chronic illnesses , '' she says . Health.com : How the financial crisis could break your heart , literally . While placebo-controlled studies are still needed to define vitamin D 's real relationship with heart disease , `` it is such a safe and possibly preventive treatment , there 's not really any reason to wait until that research is conducted , '' she adds . O'Keefe and his colleagues at the University of Alabama , the Mayo Clinic , and the vitamin D laboratory at Boston University recommend that people with cardiovascular disease or related risk factors -- such as smoking , obesity , diabetes , or a family history -- have their vitamin D levels checked by a doctor . Health.com : 7 Causes of High Cholesterol . To restore normal vitamin D levels , deficient at-risk patients should be supplemented with 50,000 IUs of prescription vitamin D2 or D3 ( vitamin D comes in two forms ) once a week for 8 to 12 weeks , according to the report 's authors . They should then maintain these levels with either 50,000 units every two weeks , 1,000 to 2,000 IUs of vitamin D3 every day , or approximately 10 minutes of sunlight a day between the hours of 10 a.m. to 3 p.m. Health.com : Vitamin Guidelines : Easy Ways to Double Your D. Harris agrees with most of these recommendations , although she warns that sun exposure in the northern United States during the months of November through April tends to be an inadequate source of vitamin D. The bottom line , says O'Keefe , is that adequate vitamin D levels are a necessity for overall health -- and they probably improve heart functioning as well . `` Deficiency really wreaks havoc on long-term health , '' he says . `` And so even though [ the cardiovascular benefit ] is still theoretical , we have a mandate to normalize levels in heart patients -- and really in all patients -- just for the good it will do the rest of their system . '' Health.com : How I survived a heart attack at 43 . O'Keefe is an unpaid consultant for CardioTabs , a supplement maker , and the group practice where he works uses the supplement company 's funds for marketing and patient education . Try a FREE TRIAL issue of Health - CLICK HERE ! Copyright Health Magazine 2009 .
Study : Low levels of vitamin D may increase the risk of cardiovascular disease . About 40 to 50 % of people do n't get enough vitamin D says study author . Sun in northern U.S. may not generate enough vitamin D during winter months . More research needed to pinpoint role of vitamin D and cardiovascular disease .