against infection and adverse outcomes . In fact , several observational studies have shown a strong relationship between low serum vitamin D levels and the development of COVID-19 . Moreover , a meta-analysis of 54 studies including 1.4 million patients found that those with low vitamin D levels were at a higher risk of intensive care admission and death following infection with the virus . But not all studies have been positive with some unable to detect an association between the vitamin and adverse COVID-19-related outcomes . One way to better understand whether vitamin D might protect against COVID-19 would be prospectively follow those prescribed vitamin D before the pandemic and who then continued with the supplement during the pandemic . This was exactly what was done in a study by US researchers .
They used data from a population of US veterans prescribed vitamin D from January 2019 to December 2022 for either a deficiency syndrome or another related reason . Individuals prescribed either oral cholecalciferol ( vitamin D3 ) or calcifediol ( vitamin D2 ) were matched with control patients who had never been prescribed the supplement . The primary exposure for the study was either vitamin D3 or D2 supplementation before and after the pandemic began and the primary outcome of interest was a laboratory confirmed COVID-19 infection and COVID-19-related mortality was examined as a secondary outcome .
A total of 34,710 individuals with a mean age of 58 years ( 1.3 % female ) were prescribed vitamin D2 and 220,265 with a mean age of 63 years ( 11 % female ) were prescribed vitamin D3 . Use of vitamin D2 was associated with a significant reduction in the risk of COVID-19 infection ( hazard ratio , HR = 0.72 , 95 % CI 0.65 – 0.79 ) as was vitamin D3 ( HR = 0.80 , 95 % CI 0.77 – 0.83 ). In addition , there was also a significant reduction in COVID-19- related mortality but only for those taking vitamin D3 ( HR = 0.67 , 95 % CI 0.59 – 0.75 ), vitamin D2 ( HR = 0.75 , 95 % CI 0.55 – 1.04 ). There was also a significant reduction in the risk of infection among Black participants compared to controls ( HR = 0.71 , 95 % CI 0.65 – 0.77 ).
Based on these findings , the authors estimated that across the entire US population , there would have been 4 million fewer infections and 116,00 deaths for vitamin D3 supplementation .
In their conclusion , the authors suggested that these findings were particularly relevant to the US population given how about half of the population is estimated to have suboptimal vitamin D levels .
Reference 1 Gibbons JB et al . Association between vitamin D supplementation and COVID-19 infection and mortality . Sci Rep 2022 .
Pregnant smokers given vitamin C supplements see improvements in childhood airway function
Giving vitamin C supplements to pregnant mothers who continue to smoke results in an improvement in the lung function of their offspring but whether these positive effects continue into children remains unclear .
Research shows that at birth , newborn infants have decreased pulmonary function tests if their mothers were smokers . Furthermore , maternal smoking during pregnancy also appears to increase the risk of developing childhood wheeze and asthma and , in fact , poor airway function shortly after birth is considered to be a potential risk factor for airflow obstruction in young adults . Animal work has revealed how nicotine crosses the placenta and upregulates nicotinic receptors , reducing pulmonary function . Interestingly , the use of vitamin C appears to attenuate the impact of nicotine on lung function . Based on these findings , US researchers performed a randomised trial that compared the effect of vitamin C ( 500mg / day ) on the lung function of children born to mothers who smoked . The results showed that among the mothers assigned to vitamin C , there was an improvement in pulmonary function in their offspring compared to placebo . In a second study , the improvements in lung function were maintained in the children at 12 months with a 47.5 % decrease in the occurrence of wheeze in those whose mothers had taken vitamin C . But whether these improvements would persist is unknown , and for the present study , the same researchers followed-up on these children and reported their findings after 5 years . For the extension study , the primary outcome was set as the forced expiratory flow ( FEF ) between 25 and 75 % of expired volume ( FEF 25-75 ), whereas secondary outcomes were the FEF50 and FEF75 , all of which were assessed with spirometry . The researchers also assessed the extent to wheeze between the child ’ s 4th and 6th birthday based on a respiratory questionnaire .
A total of 251 pregnant smokers , of whom 125 were randomised to vitamin C and 192 of their offspring , were included and assessed at age 5 . Among the children whose mothers were assigned to vitamin C , there was a 17.2 %
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