The Sunshine Connection

THE PROBLEM WITH getting infected by Covid-19 is not so much the virus itself but the frenzy that it sends the immune system into. It is a fair bet that almost no one outside the medical profession had earlier heard of the term ‘cytokine storm’—the body’s overwhelming defensive reaction in the face of an unknown puzzling threat that makes it literally consume its own organs. It is what usually makes the difference between life and death. Without the cytokine storm, Covid-19 would be no more than a flu or a cold. There would be no lockdown, the shutting down of the global economy, the world would be just as it was earlier. There are a huge number of studies going on to understand why the cytokine storm happens in some cases and factors responsible for mitigating it. A team of researchers from Northwestern University set about looking at the role of Vitamin D and found severe deficiency might as much as double the risk of Covid-19–related complications. They looked at patients from countries that saw a large number of cases. Those with high deaths like Spain, Italy and the UK were also those where patients had lower Vitamin D levels.

A press release by the university of the unpublished study, which was put up in a preprint server, said that the team, led by Vadim Backman, ‘were inspired to examine vitamin D levels after noticing unexplained differences in COVID-19 mortality rates from country to country. Some people hypothesized that differences in healthcare quality, age distributions in population, testing rates or different strains of the coronavirus might be responsible’. The release added: ‘But Backman remained skeptical. ‘None of these factors appears to play a significant role,’ Backman said. The healthcare system in northern Italy is one of the best in the world. Differences in mortality exist even if one looks across the same age group. And, while the restrictions on testing do indeed vary, the disparities in mortality still exist even when we looked at countries or populations for which similar testing rates apply. ‘Instead, we saw a significant correlation with vitamin D deficiency,’ he said.’

Vitamin D has been around a long time on earth, at least for 500 million years, but its role became crucial as organisms left the waters and entered land. Its key function is to mediate the absorption of calcium bodies. When life was marine-locked, calcium was available in plenty in water and could easily be absorbed or eaten, but in land, that wasn’t the case. The solution that evolution came up with was Vitamin D made through the processing of sunlight. In his book, The Vitamin D Solution, Michael F Holick writes: ‘Land presented many new challenges, especially once life forms got bigger and had to find a way to satisfy their vitamin D requirement without relying on plants. This was millions of years, by the way, before humans came into the picture… So for reasons we don’t fully understand, it was exposure to sunlight on the skin—producing vitamin D—that permitted these animals evolving on terra firma to be able to absorb enough dietary calcium for their vertebrate skeletons.’

In recent times, it has been found that Vitamin D has many other functions, one of which is modulating immune responses in humans. This idea was central to another study published last month in a paper titled ‘The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality’ in the journal Aging Clinical and Experimental Research. The UK-based researchers believe there was good evidence for Vitamin D being useful for prevention of acute respiratory infections in general and so it needed to be looked into in relation to Covid-19. They took mean levels of Vitamin D in European countries from available literature. Then the number of Covid-19 cases and mortality in each country was taken and a statistical analysis done. A negative correlation was found between number of cases and the levels of the vitamin. So also mortality. For example, in the data that they used, which was up to April 8th, the Scandinavian countries which had high mean Vitamin D levels, also did better than other European countries which had lower levels. Dr Cristian Ilie, Research and Innovation Director, The Queen Elizabeth Hospital Foundation Trust, who was part of the study, tells Open they ‘found a crude correlation between low levels of mean Vitamin D and the number of cases per million diagnosed in various European countries, respectively, the mortality per million’.

As to why such a correlation should exist, he said, ‘Vitamin D is involved in many of the body reactions, including innate and adaptive immune response. This makes it essential for the ability of our body to fight against infections. Lack of Vitamin D may result in a myriad of diseases, such as bone problems, higher risk for diabetes but also other medical conditions, such as acute respiratory infections.’ On whether the correlation can be extended to tropical countries like India, Dr Ilie says they have already done that in another soon-to-be-published paper. ‘We have found a correlation between low levels of Vitamin D and the severity of Covid-19. I can let you know now, before publication, that India was included in our second analysis,’ he says.

In recent times, it has been found that Vitamin D helps modulate immune responses in humans

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Yet another paper on Vitamin D and Covid-19 conducted by researchers of Trinity College in Dublin, Ireland, was published in the Irish Medical Journal recently. Their release said: ‘This study shows that, counterintuitively, countries at lower latitude and typically sunny countries, such as Spain and Northern Italy, had low concentrations of vitamin D and high rates of vitamin D deficiency. These countries also experienced the highest infection and death rates in Europe. The northern latitude countries of Norway, Finland and Sweden, have higher vitamin D levels despite less UVB sunlight exposure, because supplementation and fortification of foods is more common. These Nordic countries have lower COVID-19 infection and death rates. The correlation between low vitamin D levels and death from COVID-19 is statistically significant,’ said their release. It quoted Eamon Laird, the lead researcher as saying, ‘Research like this is still exploratory and we need further trials to have concrete evidence on the level of vitamin D that is needed for optimal immune function. However, studies like this also remind us how low our vitamin D status is in the population (even in sunny countries) and adds further weight to some sort of mandatory vitamin D fortification policy. If the Nordic countries are allowed to do this, there is no reason Ireland, the UK or rest of Europe can’t either.’

These are all correlation studies and there is nothing to establish causation—that giving someone Vitamin D can directly make Covid-19 harmless. But, even if we assume, that at some point more studies might show a stronger link, does it mean Indians are any better off because of it being a tropical country with greater exposure to sunlight? Not necessarily. Study after study have shown that an extraordinarily large percentage of Indians have Vitamin D deficiency. A 2018 paper, ‘Vitamin D deficiency in India’, by AIIMS researchers in the Journal of Family Medicine and Primary Care looked at the severity of the problem here by collating the information from all the studies that had been done. Almost everyone showed that more than 50 per cent of Indians had Vitamin D deficiency. ‘The community-based Indian studies of the past decade done on apparently healthy controls reported a prevalence ranging from 50% to 94%, except for one study which reported a prevalence of 34.5% which can be due to the low cutoff. High prevalence was seen throughout the country,’ said the paper. It also gave the reasons for why the deficiency exists. These included lifestyles being increasingly restricted to indoor, preventing exposure to adequate sunlight; something which was mainly an urban phenomenon. Diets not having adequate Vitamin D and calcium was another factor. ‘Phytates and phosphates which are present in fiber rich diet, can deplete Vitamin D stores and increase calcium requirement; Increased skin pigmentation and application of sunscreens; cultural practices such as the burqa and purdah system, unspaced and unplanned pregnancies in women with dietary deficit can lead to worsening of Vitamin D status in both mother and child’ were the other reasons.

Authors of studies related to Vitamin D and Covid-19 make it a point to caution against taking Vitamin D in the expectation that it will be protection against the disease. But until causation, if any, is established, it might be a good idea to take the free source of natural Vitamin D available to mankind—exposure to sunlight. It comes without any side effects and at the very least, you will still have good bones.

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Madhavankutty Pillai

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