Vitamin C or Vitamin D: Which Resists Covid19 Better?

Prof. Arunaditya Sahay
Dean (Research)
Professor of Strategic Management, BIMTECH (View Full Profile)

Covid19 was first identified on December 31,2019 in Wuhan, China. It is a type of coronavirus that mainly causes respiratory problems apart from other health complications. Covid19 has spread all over the world, however, Antarctica is still free from this virus. There is no cure for this coronavirus though vaccines are being developed in many countries and the race for vaccine development is being fiercely competed. Presently, the treatments worldwide are based on the kind of care given for influenza (seasonal flu) as well as for other severe respiratory illnesses.

As of now, the treatment is mainly supportive as no proven medicine or vaccination has been found yet despite claims by various pharma companies and laboratories. The treatments, meanwhile, is based on the symptoms, which generally are fever, cough, difficulty in breathing and loss of taste. Taking advantage of the situation, apart from pharma companies, many food supplement companies have started producing and marketing various products and basket of products, Vitamin C or Vitamin D, that claim to improve the immune system of the body.


No doubt, Covid19 infection is caused by the virus but a   person  getting  infected  by the virus also depends on the immune system and mental health of the person concerned. It is in this  regard that I  would  like to  mention the   medical    term ‘cytokine storm’ which is the body’s  overwhelming defensive  reaction in the face of an unknown puzzling threat to its wellbeing. This ‘cytokine storm’ is known to casually makes the difference between life and death. Without the cytokine  storm,   Covid19   would be no more than a flu or a cold. There will be no need of lockdown and unlocking; the world would have been 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 what are the factors responsible for mitigating it. A team of researchers from Northwestern University set about looking   at the   role    of     Vitamin D   found   that   severe deficiency might as much  as double the risk of Covid19 related complications. They looked at patients from countries that saw a large number of cases with high deaths like Spain, Italy and the UK where   patients had lower Vitamin D  levels.

When we have common cold, we are generally advised to take lot of oranges and lime juice and to which is added Vitamin C. At times, Vitamin C supplements are prescribed to “boost” our immune systems. Vitamin C, which is basically ascorbic acid. It is readily soluble in water and participates in certain metabolic processes in human body as well as in animals.  Vitamin C is considered as necessary ingredient in the diet of human beings as it prevents scurvy which it has symptoms of weakness, sore arms and legs, feeling of tiredness, soreness and stiffness of the joints as well as of the lower extremities. Vitamin C also helps in swollen and bloody gums, and haemorrhages in the tissues of the body.

Albert Szent Gyorgyi, a Hungarian professor of medicinal chemistry is given the credit of discovering Vitamin C when he was conducting his research on scurvy during 1920s.  As per the records, Vitamin C was at first isolated in the year of 1928. Going further, in the year 1932, it was identified as the curative agent for scurvy. This immune-boosting super nutrient, Vitamin C, became famous after Linus Pauling, who won Nobel Prize twice, had brought out the   benefits perceived from this. According to him, taking large doses of vitamin C could not only prevent the common cold but also help overcome more severe illnesses such as heart disease and cancer. However, his exaggerated claims did not stand up to scientific scrutiny as some of the recent researches reveal that vitamin C generally reduces the duration of cold but does not cure the common cold.  As far as immunity against SARS-CoV-2, the virus that causes Covid19, there is even lesser evidence. I recall that once during my treatment for cold, one of the doctors treating me had said, “If you take Vitamin C, you will be cured in 7 days and if you don’t, it will take a week. Most of the physicians and epidemiologist do not believe that Vitamin C can be effective in fighting Covid19.

Since Covid19 outbreak began, firm’s world over, started marketing immunity development products which contained Vitamin C as well. Some recent studies, however, state that supplements containing Vitamin C pose little risk to patients but some other “immune-boosting” products could be harmful to human. In United States, the quantity of such products was so large that U.S. Food and Drug Administration (FDA) and the Federal Trade Commission (FTC) had to intervene. Warning letters were issued by them to seven companies against selling such unapproved products which promise to cure, treat or prevent the viral infection.

In this regard, Joe Simons, FTC Chairman had said, “These warning letters are just the first step.” The division director of New York University’s Medical Centre, Dr. Mark Mulligan, who is famous for his research on the infectious diseases and vaccine, added further that there is no evidence that suggests that various immune-boosting supplements such as green tea or echinacea and zinc help to prevent Covid19 infections. Even Julie Stefanski, who is not only a registered dietitian nutritionist but also the spokeswoman for the Academy of Nutrition & Dietetics, said, “The medical profession still doesn’t know exactly how to influence the immune system, despite what supplement products may claim.” Food and Drug Administration (FDA) and the Federal Trade Commission (FTC), too, are identifying sketchy products and pulling them out of the market based on reports from health care professionals, supplement manufacturers and above all consumers.

Notwithstanding, the FDA encourages consumers to stay informed and “be wary of hype and headlines.” In case of doubt, the FDA recommends, “let your health care professional advise you on sorting reliable information from questionable information.”

In India, however, the scenario is different as the Ministry of AYUSH is propagating to build immunity and fight against the pandemic through Ayurvedic products which have roots in the science of Ayurveda. Further, Ministry of AYUSH, have issued guidelines relating to preventive health measures as well as for boosting immunity. The guidelines more specifically deal with respiratory health. These guidelines recommend the use of various herbs which are supported by Ayurvedic literature and scientific publications. These herbs are rich in various vitamins and antioxidants. Despite this contrary views, vitamin C does not cause any harmful side effects, unless consumed in excess. 

It is generally understood that Vitamin C supplements can’t ward off the common cold, it is still quite important for our health. The journal ‘Niutrients,’ in one of its issue in 2017 stated that Vitamin C not only has an essential role in the human body but it also supports immune function of the body. Vitamin C, as an antioxidant, neutralizes free radicals generated by the body’s normal metabolism as also wards against the exposure to air pollution and other environmental stressors including ultraviolet radiation.


When virus infiltrates the body, immune cells called neutrophils are directed by Vitamin C to the site of infection for defending against free radicals and thus an effective immune response to virus attack is launched. Vitamin C, however, cannot be made by human body nor the body can store for considerable time as Vitamin C, which dissolves in water, once ingested is excreted through passing of the urine.


Our daily requirement of Vitamin C can be easily met by consuming fruits, vegetables and fortified foods, which are rich in vitamin. The dose of Vitamin C recommended depends on the person’s sex, age, pregnancy and breastfeeding status. 90 milligrams (mg) of Vitamin C per day is generally recommended for an adult man whereas the dose recommendation for an adult woman is 75 mg per day. Smokers are required to take higher doses as smoking depletes Vitamin C available in the body; they need to take additional dose of 35 mg. 


As for Vitamin D, it   is believed to be on earth for over at least for 500 million years. The role of Vitamin D became crucial as some organisms started leaving the waters and started entering into land. The key function of Vitamin D, as is known today, is to mediate the absorption of calcium bodies.  Earlier, life was marine-locked where calcium was   available  in plenty; it could  be  easily absorbed or eaten. When organisms migrated to land, this source of calcium was not available to them.

Vitamin D, as we know it today was discovered by Sir Edward Mellanby while making the study of rickets in early 19th century. Earlier, he had observed that vitamin A was responsible for the prevention of rickets; such a conclusion was made because he could cure the disease by providing cod liver oil to the patients that contained Vitamin A. Later, when he moved to Johns Hopkins University, he observed that patients of rickets got cured even after destroying Vitamin A in cod liver oil. McCollum et al., observed and later concluded that rickets was cured by a new vitamin – Vitamin D, the name that was given by them. Around this time, a physician in Vienna named Huldshinsky another team in England led by Chick observed that summer sunlight or artificially produced ultra violet light cured rickets in children suffering from rickets. Hess and Unger, too, observed this phenomenon of sunlight curing rickets.

Thus, it was concluded that sunlight contains Vitamin D. It took quite some time before Vitamin D was discovered to belong to a group of fat-soluble secosteroids. The intake of this vitamin increases the absorption of calcium, magnesium and phosphate in the body and produces some other multiple biological effects. Vitamin D has been found in five different forms named Vitamin D1, D2, D3, D4 and D5. The most important compounds in this group found in human body are vitamin D3, and vitamin D2; the former is known as cholecalciferol while the latter is known as ergocalciferol.

The varying Covid19 mortality rates between countries drew the attention of many scientists, Vadim Backman being one of the most interested one. He was inspired to examine vitamin levels to explain differences in mortality rate among Covid19 patients.      Scientists have put forward various   hypotheses like differences in age distributions in population, healthcare quality, testing rates and different strains of the corona virus causing this difference.  However, Backman remained    sceptical about them; he believed that none of these factors hardly play any significant role. He thought, “The healthcare system in northern Italy is one of the best in the world, even then there was high mortality rate. The disparities in mortality still exist even when he looked at countries or   populations for  which  the  testing  rates  were similar. He found a significant correlation between the mortality rate and Vitamin D deficiency.”

In recent times, it has been found that Vitamin D has many other functions, one of which is modulating immune responses in human beings. The journal “Aging Clinical and Experimental Research” had published a paper titled,  “The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality” in which this was the central idea.  The UK-based researchers believe that there was good evidence for VitaminD to be useful for prevention of acute respiratory infections in general and also in relation to Covid-19. In their study, a negative correlation was found between number of cases and the levels of   the  Vitamin D. It was so in case of   mortality rate as well.

 For example, the Scandinavian countries which have high mean Vitamin D levels, did better than other European countries which had lower levels of Vitamin D.  Dr Cristian  Ilie,  Research and Innovation Director, The Queen Elizabeth  Hospital  Foundation Trust, who was   part  of  the  study,   found a crude  correlation between low levels of mean Vitamin D and the  number  of  cases  per  million  diagnosed  in  various European countries as also the the mortality rate per million.’ Explaining the correlation observed 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 0f 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 and  respiratory infections.

‘Irish Medical Journal’   has published yet another paper on Vitamin D and Covid-19 which was conducted by re searchers of Trinity College in Dublin, Ireland, in which gresearchers observed that countries at lower latitude and typically sunny countries, such as Spain and Northern Italy, had low concentrations of Vitamin and high rates of VitaminD deficiency in their population. 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 UV sunlight exposure, because supplementation and fortification of foods is more common.

Therefore, these Nordic countries have lower COVID-19 infection and death rates and thus, the correlation between low vitamin levels and death from COVID-19 is statistically significant. The lead researcher, Eamon Laird states, ‘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 status is in the population (even in sunny countries). They recommended high weightage for some sort of mandatory vitamin fortification in health policy. If the Nordic countries are allowed fortify foodstuff with vitamins,   there is no reason why Ireland, the UK or rest of   Europe  can’t  do it.’ These correlation studies, however, do not establish any causation, i.e, administration of Vitamin D can directly make Covid-19 harmless.

India is a tropical country with abundance of UV sunlight but study after study has shown that an extraordinarily large percentage of Indians have Vitamin D deficiency.   ‘Vitamin D deficiency in India’, a 2018 paper, by AIIMS researchers in the “Journal of Family Medicine and Primary Care” studied the severity of the problem in the country by collating the information from all the studies that had been done earlier. Almosteveryoneshowedthatmorethan50 percent of Indians were deficient in Vitamin D. The study reported, “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.” The paper has also given the reasons for Vitamin D deficiency. 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 yet 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 some  of  the other reasons for this. Various authors of studies related to Vitamin D and Covid-19 make it   a point that Vitamin D alone       cannot   be the Covid19 though it can be one of the ingredients for avoidance or  treatment of the disease. Majority of them, however, have stated that it might be a good idea to take the free source of natural Vitamin D available to mankind, that is, exposure to sunlight as it comes without   any   side   effects and  even if   it   does   not   cure Covid19,  at  the   least, it   will help in fortifying the bones.

Be that as it may, I have been a diabetic myself for last 30 years and had undergone some surgeries including brain surgery due to pituitary adenoma. From time to time the treating doctors, apart from prescribing relevant medicines, did prescribe Vitamin B, Vitamin C, Vitamin D and Vitamin E, both as standalone or in combination. At times, I was also advised to stand in sun for 15 minutes every day, perhaps, because the sun rays provide Vitamin D. Personally, I cannot judge even today about their efficacy though I know that I recovered from my ailment when these Vitamins were given along with the medicines for the treatment of the disease or for healing the wound caused by the surgery. In these Covid19 days, Vitamin C and Vitamin D have come in prominence and are being marketed vigorously under various trade names either singly or in combination. Research is still going on these Vitamins, especially with respect to their effectiveness for immunity development against Covid19. Can anyone say which is more effective?

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