It has long been widely believed that vitamin D deficiency is associated with bone health, leading to decreased bone density, osteoporosis, increased risk of fractures, and falls. Now, many studies have confirmed that vitamin D deficiency is related to the severity of COVID-19 infection.
1. The level of vitamin D is related to the severity of the disease after COVID-19 infection
In 2022, a study published in the Nature sub journal Scientific Reports pointed out that vitamin D deficiency is associated with decreased immune function, which may lead to viral infection. Studies have shown that vitamin D deficiency is associated with an increased risk of COVID-19 infection. Among American veterans, the infection rate of COVID-19 decreased by 28% and 20% respectively among those who took vitamin D2 and D3. Vitamin D3 supplementation can reduce the mortality of patients within 30 days after COVID-19 infection by 33%, and vitamin D2 supplementation can also reduce the mortality within 30 days after infection by 25%. Veterans who take high doses of vitamin D benefit more than those who take low doses. As a safe, widely available and affordable treatment, taking vitamin D may help reduce the severity of the COVID-19 epidemic.
A systematic evaluation and meta-analysis published on August 31, 2022, which collected data from 38 studies and 205565 patients, confirmed that vitamin D supplementation could improve the condition of COVID-19 infected people, and was associated with a significant reduction in the risk of severe COVID-19 infection; Vitamin D supplementation in the early stages of infection is associated with shorter hospital stay, reduced oxygen demand, and reduced mortality in hospitalized patients.
In 2022, a meta-analysis involving 21 studies pointed out that the vitamin D deficiency rate of COVID-19 severe patients was 65% higher than that of mild cases. The low level of vitamin D will increase the hospitalization rate and mortality rate of patients with COVID-19 infection. The lack of vitamin D is positively related to the severity of the disease.
2. Mechanism of vitamin D against COVID-19
How vitamin D plays a role in reducing COVID-19 infection and the severity of infection is still not particularly clear. One of the hypotheses is that vitamin D can help the body resist the damage caused by COVID-19 by up regulating the expression of ACE2. ACE2 has been proved to be the key receptor of COVID-19, and COVID-19 can down regulate its expression, causing tissue damage. Vitamin D is a negative endocrine RAS regulator that can upregulate the expression and concentration of ACE2 and has a potential protective effect on tissues.
Expert consensus version 32023 recommends adding vitamin D testing to the "Yangkang" population
Many studies have shown that there is a positive correlation between vitamin D deficiency and the severity of COVID-19, and the proportion of severe patients and hospitalization rate in vitamin D deficiency population have increased. Based on these research results, the Expert Consensus on Special Items of Health Examination for People in Rehabilitation Period from novel coronavirus Infection issued by the Chinese Medical Association on January 8, 2023 recommended that the "Yangkang" population increase the detection of vitamin D items.
4. Conclusion
With the deepening of research, more and more biological effects of vitamin D have been discovered, and its effects are no longer limited to calcium and phosphorus metabolism and bone health. Attention should be paid to population health management and regular testing of 25 (OH) vitamin D. Especially for COVID-19 Yangkang population, it is particularly important to include 25 (OH) vitamin D in the physical examination package and conduct regular testing to ensure adequate vitamin D.