• 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
Fatigue

why fatigue should not be ignored

Feeling tired occasionally is a normal response to physical exertion, lack of sleep or emotional stress. However, when fatigue becomes persistent, overwhelming or unexplained, it should not be dismissed. Fatigue is one of the most common symptoms reported in healthcare, yet it is also one of the most frequently ignored.

Understanding why fatigue should not be ignored is essential because it often acts as an early warning sign of deeper physical or mental health issues.

 

What Is Fatigue?

Fatigue is a state of ongoing physical, mental or emotional exhaustion that:

  • lasts longer than expected
     

  • interferes with daily activities
     

  • does not improve with rest or sleep
     

Unlike ordinary tiredness, fatigue affects motivation, concentration and overall functioning.

 

Why Fatigue Is Commonly Ignored

Fatigue is often dismissed because:

  • busy lifestyles normalise exhaustion
     

  • symptoms develop gradually
     

  • people attribute fatigue to stress or ageing
     

  • rest temporarily masks the issue
     

Ignoring fatigue allows underlying conditions to progress unnoticed.

 

Common Medical Causes of Persistent Fatigue

Nutritional Deficiencies

Deficiencies in:

  • iron
     

  • vitamin B12
     

  • vitamin D
     

  • magnesium
     

can significantly reduce energy levels and cause weakness.

 

Anaemia

Anaemia reduces oxygen delivery to tissues, leading to:

  • constant tiredness
     

  • breathlessness
     

  • dizziness
     

It is one of the most common yet underdiagnosed causes of fatigue.

 

Thyroid Disorders

Both underactive and overactive thyroid conditions affect metabolism.

Symptoms include:

  • fatigue
     

  • weight changes
     

  • cold or heat intolerance
     

Thyroid-related fatigue often persists despite rest.

 

Chronic Infections

Low-grade or unresolved infections keep the immune system activated, causing prolonged fatigue.

 

Hormonal Imbalance

Hormones regulate energy, sleep and metabolism.

Imbalance may lead to:

  • exhaustion
     

  • poor sleep
     

  • low motivation
     

 

Poor Sleep Quality

Even with sufficient sleep duration, poor sleep quality can cause fatigue due to:

  • sleep apnea
     

  • frequent awakenings
     

  • stress-related insomnia
     

 

Mental Health Conditions

Anxiety, depression and chronic stress commonly present with fatigue as a primary symptom.

Mental fatigue is as real and impactful as physical fatigue.

 

Lifestyle Factors That Worsen Fatigue

Certain habits intensify tiredness:

  • irregular meals
     

  • excessive caffeine
     

  • dehydration
     

  • lack of physical activity
     

  • prolonged screen use
     

Lifestyle-related fatigue often coexists with medical causes.

 

How Fatigue Affects Daily Life

Persistent fatigue impacts:

  • work performance
     

  • concentration and memory
     

  • emotional regulation
     

  • physical activity
     

  • social relationships
     

Over time, quality of life declines significantly.

 

Warning Signs That Fatigue Needs Medical Attention

Seek evaluation if fatigue:

  • lasts more than two weeks
     

  • worsens progressively
     

  • occurs with weight loss or fever
     

  • is associated with breathlessness
     

  • interferes with daily tasks
     

These signs suggest an underlying issue.

 

Why Early Evaluation Matters

Early identification of fatigue causes:

  • prevents disease progression
     

  • simplifies treatment
     

  • improves recovery time
     

  • restores normal energy levels
     

Delayed care often leads to chronic complications.

 

Diagnostic Evaluation for Fatigue

Assessment may include:

  • detailed history
     

  • blood tests
     

  • nutritional screening
     

  • hormonal evaluation
     

  • sleep assessment
     

Testing helps identify root causes rather than treating symptoms alone.

 

Can Fatigue Be Prevented?

Some preventive measures include:

  • balanced nutrition
     

  • adequate hydration
     

  • regular physical activity
     

  • consistent sleep routine
     

  • stress management
     

However, prevention does not replace evaluation when fatigue persists.

 

Fatigue and Chronic Disease Risk

Long-term fatigue may be linked to:

  • cardiovascular disease
     

  • metabolic disorders
     

  • immune dysfunction
     

This makes fatigue an important early health signal.

 

When Rest Is Not Enough

If energy does not return after:

  • adequate sleep
     

  • reduced workload
     

  • lifestyle changes
     

medical evaluation is essential.

 

The Cost of Ignoring Fatigue

Ignoring fatigue can lead to:

  • delayed diagnosis
     

  • worsening health conditions
     

  • reduced productivity
     

  • emotional burnout
     

Listening to the body early prevents long-term consequences.

 

Conclusion

Fatigue is not merely a sign of a busy life—it is often the body’s way of signalling imbalance or illness. Persistent tiredness that does not improve with rest should never be ignored. Whether caused by nutritional deficiencies, hormonal changes, chronic stress or underlying disease, fatigue deserves attention. Early evaluation and timely care can restore energy, prevent complications and significantly improve quality of life. Listening to fatigue is an act of self-care and preventive health.

 

References

  • Indian Council of Medical Research (ICMR) – Fatigue and Lifestyle Health Report

  •  World Health Organization (WHO) – Chronic Fatigue and Health Guidelines

  •  National Institute of Nutrition (NIN) – Nutrient Deficiency and Energy Research

  • Lancet – Fatigue as a Marker of Chronic Disease Studie

  •  Indian Journal of Medicine – Persistent Fatigue and Diagnosis

  • Statista – Fatigue, Stress and Health Trend Analysis

See all

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