It is a cold morning in the depth of winter.

And I think I have left my warm clothes in the changing room with my purity because I roam the edge of a reservoir in my floating shorts.

A bright colored chalk sign informs me that today the water temperature is a chili 3.9 C, as in the regular one tells me that this cold water is not swimming, this “ice” water is swimming.

How did I end here?

Well, I am fascinated by the idea of ​​increasing or increasing the immune system. My body has been a living avatar of “Quademic”, which NHS warned of all winters. It is a tireless stream of cold and cough and an explosive abdomen.

Our immune system is already doing a great job virus and other nasters. If I collected all the air during a minute, it would include 100 to 10,000 bacteria, 25,000 viruses and a single fungus during a minute, according to Prof. John Tregoning at Imperial College London London.

“You are breathing these things all the time, there is a rotating mass of pathogens (creatures caused by organisms) in the air,” they say.

But there are plenty of foods, supplements and activities that are tied for their “immune-growing” properties. Can we dial our safety?

And that’s why I find myself out and push for a chilling blast of breaststroke.

The icy water is like a fire on my skin and my whole brain may think that without the need for help from the lifeguard, it is making it in Pontoon.

But studies have shown that the adrenaline of cold water floods blood flow with cells fighting hit infections.

White blood cells – that can produce antibodies or attack infected tissue – exit your normal homes and get out of the head on patrol, thinking that there may be an infection. So does this mean that I am more preserved?

“Within a few hours, all become normal,” says Ellenor Relay, an immunologist at the University of Edinburgh.

“There is no evidence that people who swim in cold water have less cold or less infection.”

There may not be evidence for cold water, but regular exercise can do well.

A GP and expert of evidence-based medicine at St. Andrews University, Dr. On average, adults get two to three winter and five and eight children, on average, the Margaret McCartney says.

“(But) people who exercise in moderate amounts reports less viral infections,” she says.

Dr. According to Mekartney, there is a lack of decisive clinical trials, but the data we have all is, “It is good for you … but not a miraculous treatment.”

Laboratory studies have suggested that regular exercise can slow down the aging of the immune system. Your body rescue has been in decline since our 20, but research on 80 -year -old bicycles suggested that they had People’s immune system for decades,

“I know that the tests are not really done in high quality, but I am going to riding a lot of bicycles,” she says.

The first thing that rotates in my mind is vitamin C – either by eating a mountain of orange or in the form of a bullet.

Dr. Mekartney says, “It’s not me to me.” The deficiency can spoil the immune system, but very little can be obtained by excess to the vast majority. The same goes for multivitamin, which says that Dr. Mekartney only makes “expensive urine”.

However, evidence around vitamin D is warned rather than not being a firm. The level of vitamin D dips in winter as this happens when our skin is exposed to sunlight.

Dr. Says Mekartney, “I think the evidence is pointing to possible benefits for those who have got respiratory disease and who are very few in vitamin D,” Dr. Mekartney says, but “insufficient” evidence is that it will help everyone.

And when you are wondering what you can put in a shopping trolley, the jury is still on whether prebiotics and probiotics that change good bacteria in your stomach also benefit immunity.

Dr. “I am confident that it is an important area of ​​study, but we will be able to recommend it,” Says McCartney, but we will be able to recommend you. “

She also says that itchinasia, turmeric and ginger shots are not going to promote you immunity.

The capabilities of your immune system are not fixed throughout the day.

Prof. relay says, “When we wake up, our immune system is most effective at the beginning of the morning, it is highly effective through the early part of the day and then starts airing it during the day later. “

This is why your cold is often worse in the morning because your symptoms are the result of an immune system firing on all cylinders.

The decline kicks in “about four or five o’clock in the afternoon”, so if you are vaccinated, or in the morning someone is exposed to cough, you may have better protection.

As it is a 24-hour cycle in the immune system, it can help promote your immune system “due to a” a regular daily rhythm “instead of a mixture of long lies in late night and weekend”, Pro, Pro Riley says.

When we are thinking about promoting our immune system, we should also remember that there are things that actually increase our vulnerability to infection.

One of the older people is smoking as it directly damages the lungs so that they are a less effective barrier to the virus.

“If you imagine the lungs like a sieve, the smoking will break the hole in the sieve, so you can get through more,” pro traineing.

It also dials inflammation throughout the body. The inflammation is like a thermostat for the immune system and it is a common part that the body reacts to infection.

But “uncontrolled inflammation is bad for you” because it hinders the immune system “so you can respond less well”.

Obesity is another factor that can increase sensitivity to infection and also lead to severity by increasing inflammation in the body.

Dr. “Both those things may be difficult for people to stop or upside down, but they are probably the most variable.”

Constant stressed hormone cortisol levels in the body increases.

Nevertheless, cortisol moist to the immune system that can leave you more prone to infection.

Professor Treening says why it may have some beneficial effects of cold water swimming – to be in nature, for a walk, to spend time with friends.

“You are less stressed, less cortisol, so your immune system is more fit for the role that is trying to do it,” they say.

Prof. relay says: “There is no doubt that being happy, being in the positive frame of the mind, has a very important effect on our physical functions.”

You have probably seen the products in the shop that you can spray each of your nostrils on the first sign of cold.

A report in the lensate Showed that they work.

It gave thousands of people either salt water (saline) spray or gel-based. They could use it for six times a day whenever they felt that they were coming down with something.

Those who went about their daily life without just nasal sprays spent eight days on an average of getting sick during the study.

But it fell for six days in either saltwater (saline) or branded gel-based sprays.

Dr. Mekartney argues that a branded spray would not be better than normal saline spray.

If you are already doing all the common things to take care of your health – not smoking, healthy food, exercising regularly – then your immune system is already in “best possible situation”, which is already in a “best possible situation” To respond to the infection, it is called Pro relay.

“Can you do anything to promote above being a normal, healthy person? There is no real evidence that you can do,” she says.

“But there are things that you can especially do to improve your immunity against personal infections and have to be vaccinated.”

And maybe instead of spending your money on the latest immune-boosting craze, she suggests thinking about the ways of not getting infected in the first place, so “be careful about who you collect”.

Inside Health was produced by Hannah Robins and the program was broadcast on BBC Radio 4 on 09:30 GMT on Tuesday. And on BBC sounds,