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Summary

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

• Older adults
• 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

Start Here

• Facts about Vitamin D (University of Florida, Institute of Food and Agricultural Sciences) - PDF
• Vitamin D (National Institutes of Health, Office of Dietary Supplements) Also in Spanish
• Vitamin D (Hormone Health Network)
• Vitamin D and Health (Harvard School of Public Health)

Diagnosis and Tests

• Vitamin D Test (National Library of Medicine) Also in Spanish

Related Issues

• 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) Also in Spanish

Statistics and Research

• Adding a Vitamin D Supplement Likely Does Not Improve Knee Osteoarthritis (National Institute of Arthritis and Musculoskeletal and Skin Diseases)
• 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

Clinical Trials

• ClinicalTrials.gov: Vitamin D (National Institutes of Health)

Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)

• Article: Association of betatrophin amounts with 25-(OH)D levels in patients with gestational...
• Article: Vitamin D Status Is Associated With In-Hospital Mortality and Mechanical Ventilation:...
• Article: Vitamin D and Lung Outcomes in Elderly COVID-19 Patients.
• Vitamin D -- see more articles

Find an Expert

• Find a Nutrition Expert (Academy of Nutrition and Dietetics)
• Food and Drug Administration
• Food and Nutrition Information Center
• National Institutes of Health, Office of Dietary Supplements

Children

• Vitamin D and Your Child (Nemours Foundation) Also in Spanish

Women

• Breastfeeding: Vitamin D Supplementation (Centers for Disease Control and Prevention)

Patient Handouts

• 25-hydroxy vitamin D test (Medical Encyclopedia) Also in Spanish
• Calcium, vitamin D, and your bones (Medical Encyclopedia) Also in Spanish
• Hypervitaminosis D (Medical Encyclopedia) Also in Spanish
• Vitamin D (Medical Encyclopedia) Also in Spanish