Vitamin D Deficiency
Lack of vitamin D may now be a worldwide problem. It's difficult to find naturally occurring Vitamin D in most foods. Some foods are fortified with vitamin D but that can still leave a deficiency as defined by recommended daily requirements.
A Vitamin D Deficit
A vitamin D deficit may lead to increased risk of:
type 1 diabetes
NIH, Vitamin D Fact Sheet for Health Professionals, National Institues of Health, October 9, 2020, https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/, accessed 1/9/21.
Michael F Holick, Tai C Chen, April 2008, Vitamin D deficiency: a worldwide problem with health consequences, The American Journal of Clinical Nutrition, https://academic.oup.com/ajcn/article/87/4/1080S/4633477, accessed 1/11/21.