Vitamin D Deficiency and Fatigue

Relationship Between Vitamin D and Energy

Fatigue is a common complaint in patients with various conditions, including inflammatory bowel disease (IBD), and can be multifactorial in origin, with vitamin D deficiency being one potential contributor 1
Low serum levels of vitamin D have been linked specifically to muscle fatigue, which correlates well with self-reported general fatigue 1

Approximately 33% of the U.S. population had 25-(OH)D levels of 50 nmol/L (20 ng/mL) or less from 2001 to 2006, and 77% had levels less than 75 nmol/L (30 ng/mL) from 2001 to 2004 2, 3
Risk factors for vitamin D deficiency include decreased dietary vitamin D intake, decreased sun exposure, darker skin pigmentation, older age, inflammatory bowel disease, malabsorptive conditions, being homebound or institutionalized, and living at high latitudes 3, 4

Some experts recommend higher target levels, suggesting that optimal vitamin D levels should be at least 30-40 ng/mL for health benefits 5

Vitamin D has been shown to improve muscle performance in both community-dwelling and institutionalized elderly individuals 6, 7
Higher dose supplemental vitamin D (700-1000 IU/day) has been shown to improve muscle function and reduce falls by 19% 6

Consider testing for vitamin D deficiency in patients presenting with unexplained fatigue, especially when accompanied by muscle weakness or pain 1
Vitamin D supplementation should be accompanied by adequate calcium intake 5

The response to vitamin D supplementation varies based on environmental factors and starting levels of 25(OH)D; testing may be warranted after at least 3 months of supplementation 5
Dark-skinned or veiled individuals not exposed much to the sun, elderly and institutionalized individuals may benefit from vitamin D supplementation (800 IU/day) without baseline testing 5
While vitamin D deficiency is more common in populations with darker skin pigmentation, it is unclear if low 25-(OH)D levels are associated with the same adverse clinical outcomes across all ethnic groups 2, 3