Recent research shows that many people living in the United States and around the world are getting insufficient levels of vitamin D, putting them at risk for health problems. If you spend a lot of time indoors at work or home, have dark skin, are older or severely overweight or have certain medical conditions, you’re more likely to be vitamin D deficient. Even if you spend a lot of time outdoors but wisely cover up with sunscreen or sunblock, you also keep the vitamin D in sunlight from reaching your skin and being stored by your body.
Getting insufficient vitamin D has long been known to contribute to lower bone density, osteoporosis and bone fractures. (Adding vitamin D to calcium supplements helps the body better absorb the calcium it needs.) Now, having low levels of vitamin D has also been linked to cardiovascular risk and death, several cancers (including breast cancer in younger women), liver disease, multiple sclerosis and other autoimmune diseases, diabetes, periodontal disease and falls (caused by weakened muscles).