It is no surprise that one of the most popular searches on the internet right now is for ways to prevent yourself getting coronavirus.

Since the outbreak of the virus, many theories have circulated on the internet about how to best protect yourself. Some of the theories are based in fact and science; others are not.

The best advice - that is steeped in scientific evidence - is physical distancing and good hygiene:

Wash your hands for 20 seconds with soap and water. Wash your hands as soon as you come indoors. Do not touch your face with unwashed hands. Sneeze or cough into tissues and dispose of them immediately and then wash your hands. Observe physical distancing and self-isolation advice.

All of these should now be second nature to most of us, but what of the other theories circulating?

More Doctor's Notes:

Vitamin C

It is important to state clearly here that no supplement at all will cure or prevent a disease.

However, in an article published last month in the Chinese Journal of Infectious Diseases, the Shanghai Medical Association endorsed the use of high-dose vitamin C as a treatment for hospitalised people with COVID-19.

The senior expert team at the Shanghai Public Health Centre, where COVID-19 patients have been treated, reported that the dosing was in the range of 10,000mg to 20,000mg a day for seven to 10 days. This is much more than the 75mg daily recommended dose, which is found in over-the-counter supplements.

These high doses were given intravenously, through a drip directly into patients' veins, rather than via oral supplements.

Vitamin C has long been known to have an antioxidant effect.

Antioxidants are needed to maintain a healthy balance in the body. Molecules called free radicals are constantly produced by the body - usually as a by-product of day-to-day body functions. These free radicals need to be neutralised or they can damage your DNA and other important molecules in your body.

Viral infections can increase the number of free radicals your body produces, and antioxidants such as vitamin C are vital for this neutralisation. This careful balance between antioxidants and free radicals is vital for a healthy immune system.

Vitamin C, therefore, can reduce the length of viral infections such as colds if taken before the infection takes place. However, it has not been proven to prevent or cure colds.

Studies have shown that high-dose vitamin C can reduce the length of intensive care stays for patients with a variety of illnesses, including pneumonia.

The theory is that the antioxidant effect of vitamin C can reduce the inflammation that cytokines cause in the lungs.

Cytokines are small proteins released as part of the body's immune response to the coronavirus. If the body overreacts to the virus, as has been seen in some younger people who have ended up in hospital, they produce too many cytokines, leading to a "cytokine storm."

This over-production of cytokines causes excessive inflammation in the lungs, leading to breathing difficulties and even death. The idea is that vitamin C infusions, under careful hospital supervision, can reduce this cytokine storm and hence reduce inflammation and lung problems caused by the coronavirus.

Although initial studies of the use of intravenous high-dose vitamin C show promising results for coronavirus patients in ICU, it is vital to remember that a lot of this is simply theory and there is no evidence that taking vitamin C oral supplements will prevent you from getting infected with the coronavirus in the first place.

Vitamin C is mainly found in citrus fruits such as oranges and lemons, as well as dark green vegetables such as broccoli.

Garlic

Stories have been circulating online, advising people to eat more garlic as a way to fend off the coronavirus.

The theory is that garlic contains a substance known as aliin which, when eaten, is converted to sulphur-containing compounds, a process that may have an antibacterial effect.

Garlic has long been used in many countries for its antimicrobial and prebiotic effects, and it is a very healthy food source.

A study published in the Jundishapur Journal of Microbiology in 2014 concluded that garlic has some antibacterial properties - against bacteria, which are not the same as viruses - but more research is needed to support this.

There is absolutely no evidence that increasing your intake of garlic will reduce the chances of you contracting this or any virus or help you fight it in any way. The idea that it does is fake news.

Drinking water

Last month a Facebook post by a fake Japanese doctor went viral. It stated that drinking water every 15 minutes would wash the virus from your mouth into your stomach where stomach acid would kill it.

The post was shared millions of times and led to the World Health Organization (WHO) tweeting: "While staying hydrated by drinking water is important for overall health, it does not prevent coronavirus infection."

There is plenty of evidence that drinking water is vital for the overall health of your body in many ways, including gut, kidney and skin health. But there is no evidence that drinking every 15 minutes will reduce your chances of contracting the coronavirus.

Furthermore, the idea you can "wash" millions of viruses away into your stomach to be killed by stomach acid is utterly fanciful.

What you can do for now

As the pandemic continues, we will learn more about how the virus affects us and the best measures to take to prevent it. At the same time, there will be increasing numbers of fake news posts about it, and it is important we are all vigilant against this.

While hygiene and distancing measures remain key, Dr Tedros Adhanom Ghebreyesus, director of the WHO, advises that the public should:

Eat a healthy and nutritious diet that helps your immune system to function properly. Limit your alcohol consumption and avoid sugary drinks. Sugar and alcohol both have depressive effects on the immune system. Do not smoke. Smoking can increase your risk of developing severe disease if you become infected with COVID-19 because smoking contributes to respiratory problems.

That sounds like good advice to me.