Widespread vitamin D deficiency among healthcare workers leads to increased illness and reduced work capacity

Doctors, nurses, laboratory technicians, healthcare assistants, and other healthcare workers often work night or rotating shifts and experience a certain amount of stress, which contributes to an increased prevalence of vitamin D deficiency. This is reported in a review article published in Frontiers in Nutrition. The researchers discuss how vitamin D deficiency among healthcare workers negatively affects their mental and physical health, with a greater risk of infections, muscle weakness, fatigue, overweight, depression, reduced work capacity, and chronic diseases. The study sheds new light on why it is so important for healthcare workers to have adequate vitamin D levels and why higher-dose supplementation may be necessary to prevent and treat widespread deficiency.

Worldwide, healthcare workers serve as the backbone of healthcare systems, where high professional demands are often placed on them around the clock. Long working days, night or rotating shifts, stress, and irregular or unhealthy meals are therefore more common among many healthcare workers.
Vitamin D deficiency has also been shown to be more common among healthcare workers because of their working conditions and lack of sunlight.
Because vitamin D deficiency is so widespread among healthcare workers around the world, concerns have therefore been raised about their health and work capacity. The purpose of the new review article was to examine this association in closer detail:

Vitamin D deficiency affects health and work capacity in several areas

Using two databases (PubMed and Scopus) and relevant search terms, the researchers identified 36 eligible studies, which revealed the following:

• Vitamin D deficiency ranged from 30-90% among healthcare workers
• Variations in the prevalence of vitamin D deficiency depended on geographic region, season, profession and work schedules
• Age, sex, skin color, BMI and vitamin D supplementation also played key roles
• Vitamin D deficiency was associated with impaired immune function and a greater risk of respiratory infections, including COVID-19 and complications such as SARS (Severe Acute Respiratory Syndrome)
• Vitamin D deficiency was associated with muscle soreness, other muscle problems, and a greater risk of osteoporosis
• Vitamin D deficiency was associated with a higher prevalence of metabolic syndrome (a precursor to type 2 diabetes), particularly among women
• Vitamin D deficiency produced varying results with regard to fatigue, depression, and other mental health problems
• Several studies demonstrated that higher-dose vitamin D supplementation (up to 100 micrograms daily) could improve blood vitamin D levels and reduce respiratory infections
• Blood vitamin D levels above 75 nmol/L provide the best protection against respiratory infections and other deficiency-related diseases

Based on these findings, the researchers conclude that widespread vitamin D deficiency among healthcare workers constitutes a significant and serious health problem. The study also reveals a major need to address this overlooked problem, which not only increases the rate of illness among healthcare workers but also reduces their work capacity.
The researchers further state that the lower threshold for blood vitamin D levels, which is set at 50 nmol/L by most health authorities, only takes the prevention of osteoporosis into account. According to several studies, optimal levels are between 75-125 nmol/L for the prevention of respiratory infections, cardiovascular disease, and a range of other chronic diseases.

• It is a paradox that vitamin D deficiency is such an overlooked and widespread health problem among healthcare workers
• The problem can easily be detected with a blood test and addressed with appropriate supplementation at doses high enough to optimize blood vitamin D levels

Reference:

Elena Vasileiou et al. Vitamin D levels, general health status, and work productivity among healthcare workers – a scoping review of published literature (2010-2025). Frontiers in Nutrition 2026