Vitamins are substances that your body needs to grow and develop normally. Vitamin D helps your body absorb calcium. Calcium is one of the main building blocks of bone. A lack of vitamin D can lead to bone diseases such as osteoporosis or rickets. Vitamin D also has a role in your nerve, muscle, and immune systems.
You can get vitamin D in three ways: through your skin, from your diet, and from supplements. Your body forms vitamin D naturally after exposure to sunlight. However, too much sun exposure can lead to skin aging and skin cancer. So many people try to get their vitamin D from other sources.
Vitamin D-rich foods include egg yolks, saltwater fish, and liver. Some other foods, like milk and cereal, often have added vitamin D.
You can also take vitamin D supplements. Check with your health care provider to see how much you should take. People who might need extra vitamin D include
- Breastfed infants
- People with dark skin
- People with certain conditions, such as liver diseases, cystic fibrosis and Crohn's disease
- People who have obesity or have had gastric bypass surgery
NIH: National Institutes of Health Office of Dietary Supplements
- Calcium and Vitamin D: Important at Every Age (National Institute of Arthritis and Musculoskeletal and Skin Diseases) Also in Spanish
- Vitamin D and Calcium Supplementation to Prevent Fractures (U.S. Preventive Services Task Force) - PDF
- Vitamin D Toxicity: What If You Get Too Much? (Mayo Foundation for Medical Education and Research)
Statistics and Research
- Adding a Vitamin D Supplement Likely Does Not Improve Knee Osteoarthritis (National Institute of Arthritis and Musculoskeletal and Skin Diseases)
- Exposure to Cigarette Smoke Reduces Vitamin D3 in the Blood Stream and Respiratory Tract (American Academy of Allergy, Asthma, and Immunology)
- Multiple Sclerosis and Vitamin D (American Academy of Neurology) - PDF
- Vitamin D and Cancer Prevention (National Cancer Institute) Also in Spanish
- Vitamin D and Multiple Sclerosis (MS): Is There Any Connection? (Mayo Foundation for Medical Education and Research) Also in Spanish
- Vitamin D Status: United States, 2001-2006 (National Center for Health Statistics)
- ClinicalTrials.gov: Vitamin D (National Institutes of Health)
Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)
- Article: 1,25-dihydroxyvitamin-D3 promotes neutrophil apoptosis in periodontitis with type 2 diabetes...
- Article: Effect of Oral Alfacalcidol on Clinical Outcomes in Patients Without...
- Article: Efficacy and safety of alfacalcidol in Chinese postmenopausal women aged...
- Vitamin D -- see more articles
Find an Expert
- Vitamin D (Nemours Foundation)
- Breastfeeding: Vitamin D Supplementation (Centers for Disease Control and Prevention)