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Paul Marik

Paul Marik, MD: Vitamin C


  1. Humans are mutants unable to produce the stress hormone Vitamin C
  2. Acutely ill patients are vitamin C deficient
  3. Explore the critical role vitamin C plays in acute illness
  4. Review the role of vitamin C in sepsis and COVID-19


Primates and guinea pigs are unable to synthesize vitamin C. In contrast, almost all other mammals produce vitamin C in their livers with production increasing during stress.  Observations of very high vitamin C levels in the adrenal gland as well as its release in response to ACTH suggest that vitamin C plays a role in the stress response. Release of cortisol in response to stress is well documented in humans and throughout the animal kingdom. However, there is marked inter-species variation in the amount of cortisol released in response to a stressor. Interestingly, there is a strong inverse correlation between the ability of an animal to endogenously produce vitamin C and the cortisol response when stressed. Supplementation of ascorbic acid in humans and animal models is associated with a decreased cortisol response after a psychological or physical stressor.  High serum levels of cortisol in patients are associated with a poor prognosis. Traditionally, this association has been explained on the assumption that higher cortisol responses are due to a more intense physiological stress and a higher severity of illness. However, the inverse relationship of cortisol levels with vitamin C status would suggest an alternative hypothesis, namely, that high levels of cortisol and the associated poorer outcomes of patients are a function of vitamin C deficiency.


Dr. Marik received his medical degree from the University of the Witwatersrand, Johannesburg, South Africa. He was an ICU attending at Baragwanath Hospital, in Soweto, South Africa. During this time he obtained a Master of Medicine Degree, Bachelor of Science Degree in Pharmacology, Diploma in Anesthesia as well as a Diploma in Tropical Medicine and Hygiene. Dr. Marik did a Critical Care Fellowship in London, Ontario, Canada, during which time he was admitted as a Fellow to the Royal College of Physicians and Surgeon of Canada. Dr. Marik has worked in various teaching hospitals in the US since 1992. He is board certified in Internal Medicine, Critical Care Medicine, Neurocritical Care and Nutrition Science. Until recently, Dr. Marik was a tenured Professor of Medicine. Dr. Marik has written over 500 peer reviewed journal articles, 80 book chapters and authored four critical care books. He has been cited over 48 000 times in peer-reviewed publications and has an H-index of 105. He has delivered over 350 lectures at international conferences and visiting professorships. He has received numerous teaching awards, including the National Teacher of the Year award by the American College of Physicians.