Vitamin D plays an indispensable role in your body, including maintaining normal blood levels of calcium and phosphorus, working with calcium to build strong bones and regulating the immune system. You can obtain vitamin D-3, an active form of vitamin D, from fifteen minutes of exposure to sunlight without sunscreen; you can also ingest it from certain foods, such as wild salmon, egg yolks and fortified milk. Because it can be difficult to get enough vitamin D-3 through sunlight and diet, doctors sometimes recommend supplements. Consult your doctor before taking vitamin D-3.
Vitamin D-3 is one of two existing types of vitamin D, and the benefits of vitamin D apply to vitamin D-3 as well. Vitamin D-2, or ergocalciferol, is the form often incorporated in fortified milk, while vitamin D-3, or cholecalciferol, is vitamin D that has been synthesized in the skin after exposure to sunlight. Vitamins D-2 and D-3 used to be considered interchangeable; vitamin D-3 is now acknowledged to be more effective at raising levels of vitamin D in the blood; some researchers believe it to have more potent chemoprotective effects than vitamin D-2. 1000 IU is the recommended daily value of vitamin D-3. In a review published in 2010 in Nutrition Journal, authors Ran Zhang and Declan P. Naughton reported that 36 percent of healthy young adults in the United States suffer from vitamin D deficiency. When it comes to general medicine inpatients, the figure jumps to 57 percent.
When taken with calcium, vitamin D-3 can improve bone mineral density, protect against bone loss and reduce the risk of fracture. Zhang and Naughton cite a number of studies supporting the use of calcium for osteoporosis, including one in which 700 to 800 IUs of vitamin D reduced the risk of hip fractures by 26 percent. The bone-strengthening benefits of vitamin D seem to be ongoing. In a clinical study published in 2008 in the American Journal of Clinical Nutrition, supplementation with calcium- and D-fortified milk resulted in improved bone density in 100 older men. Eighteen months after the study concluded, the men still benefited from increased bone mineral density.
Vitamin D-3 may have the ability to help prevent cancer. According to Bob Sager, MD, an endocrinologist in Liberal, Kansas, people who keep their vitamin D-3 levels above 55 ng/ml can cut their risks of lung, colon, breast and prostate cancer by 50 percent. Zhang and Naughton assert that vitamin D inhibits the invasiveness and metastatic potential, or ability to spread, of cancer cells, and add that vitamin D deficiency may account for thousands of premature deaths from colon, breast, ovarian and prostate cancer a year. A four-year trial on postmenopausal women demonstrated that taking 1100 IU of vitamin D a day along with 1400 mg of calcium substantially reduced the risk of all cancers.
Low levels of vitamin D are associated with hypertension, or high blood pressure. While it's not known if vitamin D deficiency actually causes hypertension, Zhang and Naughton report that reduced blood pressure has been found in people taking vitamin D supplements, and cite a study of vitamin D-deficient elderly women who experienced a 9 percent decrease in systolic blood pressure after taking 800 IU of vitamin D and 1200 mg of calcium a day. The authors added that ultraviolet radiation also had blood pressure-lowering effects.
- American Journal of Clinical Nutrition; The Case Against Ergocalciferol As A Vitamin Supplement; Lisa A. Houghton and Reinhold Vieth; October 2006
- Your Health Matters; Vitamin D-3 Benefits; Bob Sager, M.D.; 2011
- American Journal of Clinical Nutrition; The Skeletal Benefits of Calcium- and Vitamin D-3- Fortified Milk Are Sustained in Older Men; R.M. Daly et al.; March 2008
- Nutrition Journal; Vitamin D in Health and Disease: Current Perspectives; Ran Zhang and Declan P. Naughton; 2010