However, vitamin D doesn’t occur naturally in many foods, and vegans would struggle to get enough of the vitamin without supplements in the winter.

Vitamin D levels may also be lowered due to certain medications, such as:

• Laxatives
• Steroids
• Cholesterol-lowering drugs
• Seizure-control drugs
• Rifampin – a tuberculosis drug
• Orlistat – a weight-loss drug

In addition, people suffering from certain health conditions are also at higher risk of a vitamin D deficiency.

This is true of those with cystic fibrosis, Crohn’s disease, and celiac disease.