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Vitamin C and your immunity - Here how it helps

Dr. Vivek Baliga B. is a consultant physician and cardiologist, and director of Baliga Diagnostics in Bangalore. He is a keen advocate of patient education and loves to blog about all things health related. Learn more about him at


In the midst of the Coronavirus crisis, numerous home remedies that help boost immunity have emerged. Some talk about garlic, some about turmeric, but many talk about popping in vitamin C supplements regularly to boost immunity.

The thing is though – the immune boosting properties of vitamin C is really old news. Our forefathers have always talked about eating foods that are high in vitamin C to lower our chances of picking up a common cold.

Our immune system and vitamin C

When a bacteria or virus enters our body, the defence system in the body is kickstarted into high gear. The soldiers of our body – the immune cells – jump into action and try to ­fight off the invading organism as fast as possible. While there are multiple factors at play in keeping our immune system strong, vitamin C has a vital role in keeping it powerful.

Vitamin C is not manufactured in our body. We need to source it through foods. Defi­ciency of vitamin C causes scurvy in children, which is a potentially life-threatening problem in them. Low immunity leads to increased risk of serious infections.

Vitamin C is a water-soluble vitamin, which means that it is not stored in the body. It constantly needs topping up through diet and supplements. The recommended daily allowance of vitamin C is 90 mg. Smokers need an additional 35 mg. We require around 100 to 200 mg per day of vitamin C in our diet to ensure we have enough in our bloodstream.

However, despite its wide availability in foods, we sometimes do not consume enough. This might be due to poor dietary habits (not eating enough fruits and veggies), smoking, alcohol abuse and poor socio-economic status. Pollution may also have a role in low vitamin C levels in the blood.

How does vitamin C boost immunity?

There are multiple ways vitamin C can power up your immune system.

Firstly, it is a powerful antioxidant. This means it can fi­ght harmful free radicals that are responsible for weakening the immune system, causing heart disease and similar conditions and premature ageing. The antioxidant effect is further enhanced with vitamin E.

Vitamin C is an integral part of numerous enzyme reactions within the body that maintain the structural integrity of collagen. Collagen is a part of our skin and other tissues and forms a barrier against entry of bacteria and viruses into the body. If you were to suffer an injury, vitamin C stimulates collagen synthesis and helps heal the wound faster.

When our body is invaded by a virus or bacteria, hormones called catecholamines are released to stimulate the heart. This makes the heart pump harder, delivering oxygen-rich and nutrient-rich blood to all vital organs. Vitamin C plays a pivotal role in the synthesis of these catecholamines.

The white blood cells in the body, also called leukocytes, are responsible for ­fighting off infections. Vitamin C helps increase the number of neutrophils – cells that ­fight off bacterial infections – by accumulating within each of the cells.

It also helps guide neutrophils to areas where there is an infection – a phenomenon called chemotaxis. The neutrophils then move on to ‘eat up’ the bacteria, thus removing it from the body (this is called phagocytosis). Vitamin C helps promote and enhance both chemotaxis and phagocytosis.

While there is some information on how good vitamin C is for immunity, the evidence is not really solid. There are only a few clinical trials that have looked at intravenous injections of vitamin C, rather than oral vitamin C. For example, some animal studies found that intravenous vitamin C can lower lung in‑ammation in patients with swine ‑flu.

Role in COVID infection

I am sure you are wondering whether vitamin C can protect you against the Coronavirus SARS CoV-19.

A study in a Chinese journal reported that high dose vitamin C had some bene­fit in those hospitalised with COVID infection. Those given intravenous vitamin C had some improvement in lung function.

Take the common cold. There is evidence that vitamin C supplements can shorten the duration of the cold but may not necessarily lower your chances of catching it. But you must take the supplements every day, as just taking it during the time when you are suffering from a cold has no real bene­fit.

Unfortunately, the real benefi­t against the COVID infection is not known. Studies in patients without COVID infections in an ICU setting who were administered 1-3 grams of vitamin C every day had shorter ventilation times and ICU stays.

There is a study currently underway looking at intravenous vitamin C in COVID patients in France. Currently, even in India, COVID-19 diagnosed patients are being treated with intravenous vitamin C as a part of the protocol of management.

The bottom line is that there is really no harm in taking vitamin C supplements, as it can have some effect on your immunity. These are available for adults and children as well. But don’t expect it to protect you fully from COVID-19 infections.

If you can do, include foods such as citrus fruits, broccoli, gooseberry, tomatoes, spinach, and pumpkin in your diet. These are good natural sources of vitamin C.

Remember, overdosing on vitamin C can cause loose stools, and is probably pointless anyway, as any excess will come out in your urine. Follow a healthy balanced diet, perform regular exercise, and avoid smoking and excessive alcohol.

These are the best ways to truly boost your immunity.

This article originally appeared in the TeacherTribe Magazine December 2020 edition.


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