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US researchers have found that people hospitalised with Covid-19 infection have significantly raised levels of oxidative stress, oxidant damage and markedly reduced levels of glutathione - the most abundant physiological antioxidant.

Oxidative stress results from the accumulation of free radicals, highly reactive molecules that can damage cells, membranes, lipids, proteins and DNA. Cells in the body make glutathione to protect themselves from oxidative stress. When cells fail to neutralise free radicals, harmful cellular damage can occur and potentially affect many physiological processes.

While oxidative stress is likely to increase in elderly people, the study published in the journal Antioxidants showed that Covid infection can cause the condition even in young people.

"Increased oxidative stress and reduced glutathione levels are associated with a number of conditions including ageing, diabetes, HIV infection, neurodegenerative disorders, cardiovascular disorders, neurometabolic diseases, obesity and others," said corresponding author Dr Rajagopal Sekhar, associate professor of medicine in the section of endocrinology, diabetes and metabolism at the Baylor College of Medicine.

"We suspected that Covid-19 also might be affecting oxidative stress and glutathione, and in this study we confirmed this in adults hospitalised with Covid-19. We found that these defects occur in all adult age groups, including young people, and worsen with increasing age."

The team included 60 participants (25 women, 35 men; age range 21 to 85 years old), who had been admitted to the hospital based on a diagnosis of Covid-19. The team measured the levels of oxidative stress, oxidant damage and glutathione in the patients' blood samples and compared them with those from healthy individuals.

"We were surprised to see that the Covid-19 patients in the 21 to 40 and the 41 to 60 groups had much less glutathione and more oxidative stress than the corresponding age groups without Covid-19," Sekhar said.

"This is an important new discovery," Sekhar said. "The finding that younger people with Covid-19 also are glutathione deficient and have elevated oxidative stress and oxidant damage is really surprising, because we do not normally see these defects in younger age groups. These defects appear to get progressively worse with increasing age, and the oldest patients with Covid-19 had higher level of defects in these outcomes. We propose that these changes might be involved in the disease."

The results also suggest that supplementation with GlyNAC - a combination of glutathione precursors previously shown to reduce oxidative stress and oxidant damage - and increase glutathione as well as improve health indicators such as inflammation, might be beneficial to Covid-19 patients. However, GlyNAC supplementation has not as yet been studied in association with Covid-19.