Who is at risk for vitamin D deficiency?

The following groups have an increased risk of becoming deficient in vitamin D:

• Breastfed infants because human milk is a poor source of vitamin D
• Older adults because your skin's efficiency in making vitamin D when exposed to light reduces with age, as does the kidney's ability to convert vitamin D to its active form 
• People with disorders like Chrons or celiac disease, which affect the body's ability to handle fat
• People who have obesity
• People with lymphomas
• People who have had gastric bypass surgery
• People with osteoporosis
• People with chronic kidney or liver disease
• People with hyperparathyroidism
• People with sarcoidosis, tuberculosis, histoplasmosis, or granulomatous disaese
• People who take medications that affect vitamin D metabolism, including cholestyramine, glucocorticoids, antifungal drugs, and HIV/AIDS medicines