• 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

Sleep Debt and Its Impact on the Body: Hidden Risks of Chronic Sleep Loss

Sleep is not a luxury; it is a biological necessity. Yet in today’s fast-paced world, many people consistently sacrifice sleep due to work demands, screen time and stress. Over time, insufficient sleep accumulates into what is known as sleep debt. Understanding sleep debt and its impact on the body is essential because chronic sleep loss silently affects nearly every organ system.

According to the World Health Organization and global sleep research, chronic sleep deprivation is associated with increased risk of cardiovascular disease, metabolic disorders and mental health conditions.

 

What Is Sleep Debt?

Sleep debt refers to the cumulative effect of not getting enough sleep.

For example:

  • if you need 8 hours but sleep 6 hours daily

  • you accumulate 2 hours of sleep debt per night

Over a week, that equals 14 hours of lost sleep.

This deficit places strain on the body.

 

Why Sleep Is Critical for Health

Sleep supports:

  • brain function

  • immune response

  • hormonal regulation

  • tissue repair

  • memory consolidation

Without adequate sleep, these processes become impaired.

 

Immediate Effects of Sleep Debt

Short-term consequences include:

  • daytime fatigue

  • poor concentration

  • mood swings

  • irritability

  • reduced reaction time

Even one night of poor sleep affects cognitive performance.

 

Sleep Debt and Hormonal Imbalance

Sleep regulates several key hormones.

Chronic sleep loss disrupts:

  • cortisol

  • insulin

  • leptin and ghrelin (hunger hormones)

This imbalance affects appetite, stress and metabolism.

 

Impact on Metabolic Health

Sleep debt increases:

  • insulin resistance

  • blood sugar fluctuations

  • abdominal fat accumulation

ICMR and NFHS-5 data show rising metabolic disorders in India, partly linked to lifestyle patterns including poor sleep.

 

Increased Risk of Obesity

When sleep is insufficient:

  • appetite hormones increase

  • cravings for high-calorie foods rise

  • impulse control weakens

Sleep deprivation promotes weight gain.

 

Sleep Debt and Immunity

The immune system relies heavily on sleep.

Chronic sleep loss:

  • reduces infection-fighting cells

  • increases inflammation

  • slows recovery from illness

Lancet research confirms that sleep deprivation weakens immune response.

 

Cardiovascular Consequences

Sleep debt increases risk of:

  • hypertension

  • heart disease

  • stroke

Poor sleep affects blood pressure regulation and vascular health.

 

Mental Health Impact

Sleep and mental health are deeply connected.

Sleep debt contributes to:

  • anxiety

  • depression

  • emotional instability

Chronic insomnia is both a cause and consequence of mental health disorders.

 

Cognitive Decline and Brain Health

Lack of sleep impairs:

  • memory

  • attention

  • decision-making

Over time, chronic sleep deprivation may increase risk of neurodegenerative disorders.

 

Sleep Debt and Inflammation

Chronic sleep loss elevates inflammatory markers.

Persistent inflammation contributes to:

  • metabolic syndrome

  • cardiovascular disease

  • autoimmune conditions

Preventing sleep debt reduces systemic inflammation.

 

Can Sleep Debt Be Recovered?

Short-term sleep debt can be partially recovered through:

  • consistent longer sleep

  • improved sleep hygiene

However, chronic sleep deprivation requires long-term behavioural changes.

Weekend “catch-up sleep” offers temporary relief but does not fully reverse long-standing sleep debt.

 

Warning Signs of Sleep Debt

Common indicators include:

  • reliance on caffeine

  • difficulty waking up

  • daytime drowsiness

  • poor focus

  • frequent illness

Persistent symptoms require lifestyle correction.

 

Practical Strategies to Reduce Sleep Debt

Maintain a Consistent Sleep Schedule

Go to bed and wake up at the same time daily.

 

Limit Screen Exposure Before Bed

Blue light suppresses melatonin production.

 

Create a Sleep-Friendly Environment

Dark, quiet and cool environments improve sleep quality.

 

Manage Stress

Relaxation techniques reduce cortisol levels and support sleep.

 

Avoid Heavy Meals and Caffeine at Night

These disrupt sleep cycles.

 

Role of Preventive Health Checkups

Screening helps detect:

  • hypertension

  • metabolic imbalance

  • stress-related conditions

Sleep quality assessment should be part of preventive care.

 

Long-Term Benefits of Adequate Sleep

Restorative sleep supports:

  • stable mood

  • strong immunity

  • healthy weight

  • improved productivity

  • reduced disease risk

Sleep is foundational to wellness.

 

Conclusion

Understanding sleep debt and its impact on the body highlights the critical role sleep plays in maintaining physical and mental health. Chronic sleep loss disrupts hormones, weakens immunity, increases metabolic risk and affects heart health. While occasional sleep loss may be manageable, consistent deprivation carries serious long-term consequences. Prioritising adequate, high-quality sleep is one of the most powerful steps toward protecting overall health and preventing chronic disease.

 

References

  • World Health Organization (WHO) – Sleep and Non-Communicable Diseases

  • Indian Council of Medical Research (ICMR) – Lifestyle Disorders and Sleep Patterns

  • National Family Health Survey (NFHS-5) – Adult Health Indicators

  • Lancet – Sleep Deprivation and Chronic Disease Research

  • NITI Aayog – Preventive Healthcare and Lifestyle Risk Factors

See all

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