• 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

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Insufficient water intake

How Poor Hydration Affects Joint Health: Why Water Matters for Mobility

Water is essential for nearly every function in the human body, yet many people underestimate its importance for joint health. While hydration is commonly associated with digestion and skin health, it also plays a crucial role in maintaining smooth and pain-free joint movement.

Understanding how poor hydration affects joint health can help prevent stiffness, discomfort and long-term mobility issues.

 

The Role of Water in Joint Function

Joints are where two bones meet, allowing movement and flexibility. Healthy joints rely on:

  • Cartilage
     

  • Synovial fluid
     

  • Ligaments
     

  • Tendons
     

Cartilage, which cushions bones, contains a high percentage of water. Synovial fluid acts as a lubricant, reducing friction during movement.

Proper hydration ensures these components function effectively.

 

What Happens When You Are Dehydrated?

When the body lacks sufficient water:

  • Synovial fluid production may decrease
     

  • Cartilage may lose elasticity
     

  • Joint cushioning becomes less effective
     

This can result in stiffness and discomfort.

 

1. Reduced Joint Lubrication

Synovial fluid requires adequate hydration to maintain volume and viscosity.

Without enough water:

  • Friction between bones increases
     

  • Movement becomes less smooth
     

  • Risk of wear and tear rises
     

 

2. Increased Joint Stiffness

Dehydration may cause joints to feel tight, especially:

  • In the morning
     

  • After prolonged sitting
     

  • During physical activity
     

Stiffness may limit flexibility.

 

3. Higher Risk of Injury

Poorly lubricated joints may be more prone to:

  • Sprains
     

  • Strains
     

  • Cartilage damage
     

Hydration supports tissue resilience.

 

4. Worsening of Existing Joint Conditions

Individuals with conditions such as osteoarthritis may experience increased discomfort if hydration is inadequate.

While water does not cure arthritis, it supports overall joint function.

 

5. Reduced Nutrient Delivery

Water helps transport nutrients to joint tissues.

Dehydration may impair circulation and nutrient exchange, slowing tissue repair.

 

Signs of Dehydration That May Affect Joints

  • Dry mouth
     

  • Dark urine
     

  • Fatigue
     

  • Headaches
     

  • Muscle cramps
     

  • Joint stiffness
     

Recognizing early dehydration signs prevents complications.

 

How Much Water Do You Need?

Hydration needs vary depending on:

  • Body weight
     

  • Climate
     

  • Physical activity level
     

  • Health conditions
     

On average, adults may require 2–3 liters of water daily.

In hot climates such as India, higher intake may be necessary due to increased sweating.

 

Tips to Maintain Proper Hydration

1. Drink Water Regularly

Do not wait until you feel thirsty.

 

2. Eat Water-Rich Foods

Include:

  • Cucumbers
     

  • Watermelon
     

  • Oranges
     

  • Tomatoes
     

 

3. Limit Excessive Caffeine and Alcohol

These may contribute to fluid loss.

 

4. Carry a Water Bottle

Keeping water accessible encourages consistent intake.

5. Hydrate Before and After Exercise

Physical activity increases fluid loss through sweat.

 

Hydration and Joint Health in India

In India’s hot and humid climate, dehydration is common, especially during summer months.

Outdoor workers, athletes and elderly individuals are particularly vulnerable.

Maintaining adequate hydration supports not only joint health but overall wellbeing.

 

When to Consult a Doctor

Seek medical advice if you experience:

  • Persistent joint pain
     

  • Swelling
     

  • Limited range of motion
     

  • Redness or warmth around joints
     

These may indicate underlying joint disorders requiring evaluation.

 

Conclusion

Poor hydration can negatively affect joint health by reducing lubrication, increasing stiffness and raising injury risk. Since cartilage and synovial fluid depend heavily on water, maintaining adequate hydration is essential for smooth movement and long-term mobility.

Drinking sufficient water daily is a simple yet powerful step toward protecting joint health. Combined with regular exercise and balanced nutrition, proper hydration supports active and pain-free living.

Small daily hydration habits can make a significant difference in how your joints feel and function.

 

References

  • Indian Council of Medical Research – Hydration Guidelines

  • World Health Organization – Water and Health Resources

  • Indian Journal of Orthopaedics – Joint Health Studies

  • National Institute of Nutrition India – Fluid Intake Recommendations

  • Journal of Sports Medicine – Hydration and Musculoskeletal Health Research

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