• Published on: Apr 17, 2020
  • 4 minute read
  • By: Dr Rajan Choudhary

Vitamin D In Reducing The Risk Of COVID 19

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Why Vitamin D is the only supplement we will recommend for you.

Most of our blogs have looked at theories posted on social media, and shown how they are usually not true, or have no factual basis behind them. But here we will show some evidence that supports something truly interesting, especially during the time of this pandemic.

For a number of years research has shown a possible link between vitamin D and illnesses, specifically respiratory infections. In our previous blogs we have shown that vitamin supplementation is unnecessary, except for vitamin D. Here we will show why supplementation may be in your best interest for reducing the risk of COVID.

Now I’ll be honest. Vitamin D and immunity was not something we were taught at medical school, or in medical practice. The fact that such a large amount of research exists on this topic is certainly interesting, and whilst researching this topic I have certainly learnt a lot myself, enough to change my own medical practice. And it is because of the high quality of evidence present that I feel confident in supporting the claims below.

SUMMARY

  • Many people are low in Vitamin D due to various risk factors (see our blog on vitamin D)
  • Vitamin D appears to have a role in modulating immune function
  • Low Vitamin D levels appear to increase the severity of autoimmune disorders
  • Low Vitamin D levels appear to increase the risk of getting respiratory infections
  • Vitamin D supplementation appears to reduce the risk of getting respiratory infections
  • Those who are at risk of having low vitamin D should take low dose supplementations.

If you want the good stuff, skip to the section on SUPPLEMENTATION

IMMUNE FUNCTIONS

As we’ve discussed, vitamin D is key in maintaining the right balance of calcium, ensuring the right amount is taken up from the food we eat, integrated into our bones, and removed in our urine if not required. We know that there are some people who are at risk of vitamin D deficiency, and this is more common in countries closer to the poles and with cloudy weather.

But there also appears to be a role for vitamin D in modulating the immune system. We have found many more cells in our body other than bone, intestine and kidney that possess the vitamin D receptor. These include immune cells, and one role may be to promote proliferation of these cells as well as promote their protective immunity.

AUTOIMMUNE

Due to its role in immune function, studies have been performed to see whether there is a link between autoimmune diseases and vitamin D. Common autoimmune disorders (and the organs the affect) include multiple sclerosis (nerves), rheumatoid arthritis (joints), diabetes mellitus (pancreas), inflammatory bowel disease (bowels) and systemic lupus erythematous (the entire body). All of these diseases lead to loss in function of an organ or system as the immune system recognises the organ as an “invader” and begins to destroy it.

One study looked at 161 patients with early forms of autoimmune diseases over 2 years. Out of them, 35 went on to develop full blown autoimmune disorders (like rheumatoid and lupus). Whilst the two groups of patients were mostly similar, vitamin D was noticeably lower in the group that progressed to disease. But this is one study, with a small number of patients.

Other studies have looked at vitamin D levels in patients across the globe, and the majority of them have shown there to be a correlation between low vitamin D or severe deficiency, and the severity of autoimmune disorder they have. We will not go into them in detail because this is beyond the scope of this blog, but it certainly is interesting and supports this new role for vitamin D.

RESPIRATORY INFECTIONS

We have unknowingly tried to use Vitamin D to treat infections prior to the advent of antibiotics. A common treatment for tuberculosis was to send patients to sanatoriums, where treatments included exposure to sunlight, and provision of cod liver oil, a rich source of vitamin D.

Large population studies done in the 1980s and 1990s involving 19,000 people showed that those with low vitamin D levels were more likely to self report recent upper respiratory tract infections than those with normal levels. This was true even if age, gender, season and race were accounted for. Similar studies have shown similar results when looking at rates of influenza, bacterial vaginosis and HIV.

Normally we are very skeptical with such studies, and look for weaknesses in their methodology and conclusions. After all, we could just cherry pick the studies that show a benefit. Furthermore, just because there is a trend with vitamin D levels and infection, this does not imply a direct link. More evidence is required. However, the fact 19,000 people were surveyed provides this study with good statistical power, and lends it validity. But lets look for more.

SUPPLEMENTATION

Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data – Martineau 2017, British Medical Journal

A systematic review and meta analysis is the highest level of evidence in the realm of medical research. It is the absolute pinnacle of thorough research, looking and comparing other studies with very close scrutiny to see whether we have conducted enough research worldwide to support a theory. In this case this systematic review was published in the British Medical Journal, a highly reputable source that again scrutinises any study submitted thoroughly before accepting it for publication. In my eyes, this is some of the best evidence we will have on this topic. And it is a far sight better than any WhatsApp forwards.

So what does this say?

Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit.

I don’t think I could have summarised it better myself. If you wish to read the study yourself you can use this link: https://www.bmj.com/content/356/bmj.i6583 Vitamin D supplementation to prevent acute respiratory tract infections

WHAT DOES THIS MEAN FOR ME?

If you are someone who may be at risk of vitamin D deficiency, then low dose supplements (NOT treatment dose) may be beneficial in reducing the risk of getting a respiratory infection. Since COVID is caused by a respiratory virus, we can extrapolate that Vitamin D supplementations may reduce your risk of getting COVID. This is not a cure, and it is not a guaranteed protection. If you already have a balanced diet and are not low in Vit D, it may be less beneficial.

Dr Rajan Choudhary, UK, Chief Product Officer, Second Medic Inc

www.secondmedic.com

Read Blog
 Seasonal change

common health problems during seasonal change

Seasonal changes bring relief from extreme weather, but they also pose unique challenges to human health. Transitions between summer, monsoon and winter often trigger a rise in illnesses. The body requires time to adapt to changing temperature, humidity and environmental conditions. During this adjustment period, immunity may weaken, making individuals more vulnerable to infections and other health problems.

Understanding common health problems during seasonal change helps individuals take preventive measures and seek timely care.

 

Why Seasonal Change Affects Health

Seasonal transitions impact the body in several ways:

  • sudden temperature fluctuations stress the immune system
     

  • humidity changes promote pathogen growth
     

  • allergens become more prevalent
     

  • lifestyle habits shift with weather
     

These factors collectively increase illness risk.

 

1. Respiratory Infections

Respiratory infections are among the most common health problems during seasonal change.

Causes

  • viral and bacterial growth in changing weather
     

  • increased indoor crowding
     

  • weakened respiratory defences
     

Symptoms

  • cough
     

  • sore throat
     

  • fever
     

  • nasal congestion
     

Children and elderly individuals are particularly vulnerable.

 

2. Common Cold and Flu

Seasonal transitions often coincide with cold and flu outbreaks.

Why They Increase

  • viruses survive longer in certain climates
     

  • immunity temporarily weakens
     

  • exposure increases during travel and gatherings
     

Symptoms

  • runny nose
     

  • sneezing
     

  • body aches
     

  • fatigue
     

 

3. Allergies

Seasonal allergies become prominent during weather shifts.

Common Triggers

  • pollen
     

  • dust
     

  • mould
     

  • air pollution
     

Symptoms

  • sneezing
     

  • itchy eyes
     

  • nasal congestion
     

  • throat irritation
     

Allergic symptoms can mimic infections and are often overlooked.

 

4. Digestive Problems

Digestive issues such as acidity, gas and indigestion are common during seasonal change.

Contributing Factors

  • altered eating patterns
     

  • contaminated food or water
     

  • reduced digestion efficiency
     

Symptoms

  • bloating
     

  • abdominal discomfort
     

  • nausea
     

 

5. Skin Problems

Changes in humidity and temperature affect skin health.

Common Issues

  • dryness
     

  • fungal infections
     

  • rashes
     

Poor skin barrier function increases infection risk.

 

6. Viral Fevers

Viral fevers are common during monsoon and post-monsoon periods.

Symptoms

  • sudden fever
     

  • body pain
     

  • headache
     

  • weakness
     

Early rest and hydration are essential.

 

7. Joint and Body Pain

Seasonal change may worsen joint stiffness and body aches, especially in individuals with arthritis.

Causes

  • cold weather
     

  • reduced physical activity
     

  • inflammation
     

 

Why Immunity Drops During Seasonal Change

Immunity may weaken due to:

  • temperature stress
     

  • vitamin deficiencies
     

  • poor sleep
     

  • increased stress
     

According to Indian Council of Medical Research data, immunity-related illnesses increase during transitional seasons.

 

Who Is Most at Risk?

High-risk groups include:

  • infants and children
     

  • elderly individuals
     

  • pregnant women
     

  • people with chronic diseases
     

  • individuals with low immunity
     

Extra care is required for these groups.
people with diabetes, heart disease,lung disease, kidney disease

 

Prevention of Seasonal Health Problems

Maintain Good Hygiene

Frequent handwashing reduces infection spread.

 

Support Immune Health

Balanced nutrition, hydration and adequate sleep strengthen immunity.

 

Stay Physically Active

Regular movement supports circulation and immune function.

 

Eat Fresh and Safe Food

Avoid stale or contaminated food during high-risk seasons.

 

Stay Vaccinated

Vaccination helps prevent seasonal flu and related complications.

 

Manage Allergens

Keep living spaces clean and well-ventilated.
mask use in crowded places, safe water, mosquito protection in monsoon.

 

Early Warning Signs Not to Ignore

Seek medical advice if experiencing:

  • persistent fever
     

  • breathing difficulty
     

  • severe weakness
     

  • worsening symptoms
     

Early intervention prevents complications.

 

Role of Preventive Healthcare

Preventive care focuses on:

  • early detection
     

  • risk reduction
     

  • long-term health protection
     

Seasonal health awareness is a key part of preventive medicine.

 

Long-Term Impact of Ignoring Seasonal Illness

Repeated seasonal illnesses may lead to:

  • chronic respiratory problems
     

  • weakened immunity
     

  • reduced quality of life
     

Prevention protects long-term health.

 

Conclusion

Common health problems during seasonal change include respiratory infections, colds, allergies, digestive issues and viral fevers. These conditions arise due to sudden weather changes, weakened immunity and increased exposure to pathogens. By understanding the causes and symptoms and adopting preventive measures such as good hygiene, balanced nutrition, adequate rest and timely medical care, individuals can significantly reduce seasonal illness risk. Seasonal transitions are inevitable, but proactive health practices ensure smoother adaptation and better wellbeing throughout the year.

 

References

  • Indian Council of Medical Research (ICMR) – Seasonal Disease Surveillance Report

  •  National Family Health Survey (NFHS-5) – Immunity and Morbidity Data

  • World Health Organization (WHO) – Seasonal Illness Prevention Guideline

  •  NITI Aayog – Preventive Healthcare and Climate Health Reports

  • Lancet – Climate Change and Seasonal Disease Patterns

  • Statista – Seasonal Illness Trends and Public Health Data

See all

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