According to Prof Srijit Mishra, another signatory to the letter, the recommendation is Vitamin D intake for adults of up to 4,000 international Units (IU) or 100 microgrammes (mcg) daily. Those at an increased risk of deficiency due to excess weight, dark skin, or living in care homes may need higher intakes.
“The current evidence suggests that 25-hydroxyvitamin D serum levels over 30 nanograms per millilitre (ng/ml), a test to measure Vitamin D level is a widely endorsed minimum to reduce COVID-19 risk,” Mishra, from Mumbai’s Indira Gandhi Institute of Development Research (IGIDR), told PTI.
Bal said Vitamin D is generally known to have many beneficial contributions in immune responses, and added, “There are no reports, to the best of my knowledge, where there are radical improvements brought about by supplementation of Vitamin D in normal individuals.”
In her judgment, Vitamin D can have an additional role to play along with other medications but not a primary role. The linkage between Vitamin D and better immune competence does exist based on experimental data, and data on patients is almost invariably associative and does not prove a cause-and-effect relationship, she said.
While no clinical trials have tested Vitamin D’s efficacy as a treatment or a preventive measure, several studies have found an association between low levels of Vitamin D and COVID-19.
However, a review of five of these studies by the National Institute for Health and Care Excellence (NICE) in the UK concludes that the studies provide no evidence that Vitamin D levels influence the risk of getting COVID-19 or dying as a result.
“There is no evidence to support taking Vitamin D supplements to specifically prevent or treat COVID-19,” authors of the study wrote.
Mishra also noted that the evidence so far on risk-factors of COVID-19 with low Vitamin D level is associational, with some studies pointing out that low levels of the vitamin had a higher risk in infection and positivity rates.
He said a communication from UK-based NNEdPro Global Centre for Nutrition and Health has brought out a 10-point summary on diet, nutrition and the role of micronutrients for combating COVID-19.
“The note identifies the relevance of various micronutrients, including Vitamin D. However, as the NNEdPro write-up clearly points out, this advice on nutritional adequacy should not be constituted as a substitute for key public health and medical advice on prevention,” Mishra said.