Vitamin D Deficiency, Obesity & Diabetes Linked To Higher Rates Of Infection & Mortality

Vitamin D supplementation has been called for by researchers in Ireland to reduce the severity of COVID-19 symptoms. Studies in France have found that elderly people who previously have taken vitamin D3 supplements were more likely to survive/have better outcomes. A team of researchers from America, Europe, and the UK have written an open letter to world governments calling for immediate increased daily intake of vitamin D for healthy adults as an intervention to help reduce COVID-19 infection, hospitalization, and mortality. 

Individual countries in Asia, including China, are reporting associations between vitamin D deficiency and COVID-19 infection and mortality, with serum vitamin D concentrations being found to be significantly lower in COVID-19 patients. Now a team of international researchers from Australia, India, and Sri Lanka have conducted an analysis of vitamin D prevalence with infections and mortalities across Asia comprising 24 countries, also assessing the effect of confounding factors such as obesity and diabetes which are known additional risk factors for infection and mortality. 

For this study published in the Diabetes & Metabolic Syndrome: Clinical Research & Reviews journal, data was collected on COVID-19 infection and mortalities from the Worldometer website, this data included the records derived directly from official government reports of individual countries and/or indirectly through reliable local resources. W.H.O’s non-communicable disease country profiles database was used to extract information for the confounding factors, obesity, and diabetes prevalence; obesity was defined as a BMI ≥30, and diabetes was defined as a fasting glucose concentration ≥ 7.0 mmol/l.  Additionally, information regarding the prevalence of vitamin D deficiency in each country was collected from literature searching PubMed and Google scholar; deficiency was defined as being a serum concentration of less than 20 ng/ml (25(OH)D).

All Western Asian countries including Kuwait, Qatar, and Lebanon reported higher values for COVID-19 infections and mortalities compared to South East Asian countries such as Brunei, Vietnam, and Singapore. Infections were lowest in Vietnam at 15 infections per one million people, with Bahrain having the highest at 53,679 infections per one million people. Vietnam reported the lowest death at 0.4 deaths per million people, while Iran reported the highest deaths at 655 per one million people. 

This study found that more than 50% of the adult population in 18 of the 24 countries were vitamin D deficient, with the lowest vitamin D deficiency being reported in Vietnam of only 2% while the highest was reported in Oman at 87.5% being deficient in vitamin D. The findings were prominent despite the Gulf region receiving an endless supply of sunlight, which may be due to cultural and social habits limiting exposure to sunlight. Prevalence of diabetes was around the same levels across the 24 countries at 10% of the population, and obesity prevalence was reported to be highest in Bahrain at 35% while being the lowest in Vietnam at only 2%.

In this study, Vitamin D deficiency was significantly associated with COVID-19 infections and mortality across all 24 countries, and they were also more significant in those with obesity and diabetes.

It is important to restore and maintain immune balance because COVID-19 is believed to be caused by a dysregulation of the immune system which causes a hyperinflammatory cytokine storm to combat the virus. This study suggests vitamin D has a protective effect in reducing the infectivity and mortality of COVID-19. 

“People who are deficient in vitamin D may receive daily or weekly supplementation as it is studied to protect against acute respiratory tract infections. The population at higher risk of vitamin D deficiency during this global pandemic should consider taking vitamin D supplements to maintain the circulating 25(OH)D in optimal levels (75-125 nmol/l),” write the authors. 

The researchers suggest that it may have been more precise to have collected data for each country individually, as BMI value may differ by region, and the data extracted from the W.H.O databases could have been outdated. 

“Obesity cut off values may differ from this database, when focused on Asia as the cut off value would be lower due to the different body composition.”