Obesity, vitamin D deficiency and old age a serious combination with respect to coronavirus disease-2019 severity and outcome

Curr Opin Clin Nutr Metab Care. 2021 Jan;24(1):18-24. doi: 10.1097/MCO.0000000000000700.


Purpose of review: Old age, obesity and vitamin D deficiency are considered as independent risk factors for severe courses of COVID-19. The aim of the review is to discuss common features of these risk factors and the impact of vitamin D.

Recent findings: The recently discovered relationship between vitamin D and the infection pathway of the virus via the renin--angiotensin system (RAS) and the adipokines leptin and adiponectin play an important role. The frequency of studies showing a relationship between a low vitamin D status in comorbidities and severe COVID-19 courses makes an impact of vitamin D effects likely.

Summary: There is a direct relationship between vitamin D, body fat and age in COVID-19 courses. With age, the ability of the skin to synthesize vitamin D decreases, and leads to vitamin D-deficits. If the skin is insufficiently exposed to sunlight, severe deficits can develop. As vitamin D plays an important role not only in the immune system but also in the RAS, and thus at the point where the virus attacks, a good vitamin D supply is an important basis for reducing the risk of severe COVID-19 processes. Treatment with vitamin D supplements should be based on severity of the vitamin D deficiency.

Publication types

  • Review

MeSH terms

  • Adipose Tissue
  • Aged
  • Aging*
  • COVID-19* / complications
  • COVID-19* / epidemiology
  • COVID-19* / metabolism
  • Comorbidity
  • Dietary Supplements
  • Humans
  • Nutritional Status*
  • Obesity / epidemiology*
  • Pandemics
  • Renin-Angiotensin System
  • Risk Factors
  • SARS-CoV-2
  • Severity of Illness Index*
  • Sunlight
  • Vitamin D Deficiency / complications*
  • Vitamin D Deficiency / drug therapy
  • Vitamin D Deficiency / epidemiology
  • Vitamin D* / metabolism
  • Vitamin D* / therapeutic use
  • Vitamins / metabolism
  • Vitamins / therapeutic use


  • Vitamins
  • Vitamin D