Two researchers from The Department of Immunology and Microbiology from the University of Copenhagen have been asked whether the advice to beat colds we find online is actually factual. One of these researchers is Jan Pravsgaard Christensen and the other is assistant professor Tim Holm Jakobsen.
Immunity does not come from what we eat
Firstly, they underline the fact that immunity cannot be obtained by eating certain things. When we are infected by a microorganism that the immune system has not met before, it is necessary for the immune system to develop specific cells capable of fighting the unknown microorganism. It can take a couple of days for the body to develop an adequate amount of these cells to eliminate the microorganism. In the meantime, we experience symptoms of a common cold. Therefore, it is not possible to eat certain foods that make the body produce these specific cells in advance.
Prevention is the way to go
Once you have caught a common cold, the damage is already done, and the immune system is preparing to fight the microorganism. Then, it will be too late to start eating certain foods to fight the microorganism. On the other hand, you can do several things to prevent a common cold, and Jan Pravsgaard Christensen recommends that you generally have a healthy lifestyle which involves:
- Getting a good night’s sleep and feeling well-rested
- Eating a healthy, varied diet, and thus getting enough vitamins and minerals
- Considering taking a vitamin supplement during the winter where the sun only shines sparsely
- Washing your hands frequently and sneezing into a tissue or your sleeve to avoid infecting others
- Staying away from smoking
In addition, the professor brings out an interesting factor which contributes to the reduction of annual sick-days; being happy. If you handle the sickness well, it is in fact easier to recover. Those who are alone tend to have a higher mortality and thus a greater tendency to fall ill. Research has shown that when you are happy, the secretion of antimatter on the mucosa is increased and the secretion of cortisol in the saliva glands is reduced. These two mechanisms strengthen the immune system. How exactly the brain and the immune system work together, however, remains unclear, but these two measurable changes indicate that the feeling of happiness benefits the immune system.
Additionally, data support the hypothesis that people with a more negative emotional life are worse at fighting disease. Therefore, they are at a greater risk of falling ill than those with a more positive emotional life.
In the opposite case, stress can affect your immune system negatively making you more vulnerable to unfamiliar pathogenic microorganisms. A little stress does not harm, but too much stress will increase the level of cortisol to an extent which does more harm than good. As an example, going for a run will put too much strain on the body if you have a fever as the body’s metabolic activity is already increased in this situation. Running will increase this metabolic activity further and put more strain on the body. The body gets a fever because it helps the immune system fight the infection faster, and therefore, some people will find that hot beverages such as tea reduces the duration of the illness. This is not because of certain ingredients in the tea, but rather that it keeps the mucosa warm.
Is there no way to get well by eating?
Assistant professor Tim Holm Jakobsen does not reject the idea that certain natural substances can have a health-promoting effect but he is doubtful as to the idea that you can eat to feel better once you have caught the common cold. As an example, some of the active substances found in medicaments come from certain vegetables, but this does not mean that you will get the same effect from eating the fresh vegetable in question. It may for instance be necessary to heat or otherwise treat the substance in order for it to become active. In addition, the concentration of just the one active substance in the food product is often much smaller than in the preparation, so you would have to eat a lot to achieve the same effect. A pill might thus contain an amount of active substances equivalent to the amount found in 50 cloves of garlic. It is therefore important to use common sense when reading advice on how to fight illness to avoid wasting money.
So, what actually works?
Studies have researched several foods and their effect on a common cold, and here are some of the foods that have been scientifically studied and proven efficient:
- Menthol: It can relieve a blocked nose and a sore throat. It can act as a local anaesthetic and thus soothe a cough. In addition, it can kill bacteria.
- Garlic: It contains the substance ajoene which is antimicrobial. The substance is activated when the garlic is damaged (chopped or crushed) or heated. However, a large amount is required and it is therefore doubtful what effect normal amounts have on the immune system.
- Echinacea: Some studies have shown that it stimulates the white blood cells and thus benefit the immune system.
- Zinc: This substance is necessary for a wide range of processes in the body to function. At the same time, it can prevent viruses from dividing as it inhibits their production of protein, an important building block for viruses. Results from studies which have examined zinc are, however, not unambiguous as some indicate that there is a beneficial effect, while others do not. Some studies suggest that zinc may reduce the duration of the disease.
- Antioxidants: A white blood cell uses oxidising agents to fight pathogenic microorganisms, but this activity can also damage healthy cells and cause inflammation which results in heavy common cold symptoms. In this way, a supplement of vitamin C, which contains antioxidants, can have a health-promoting effect. However, this only applies if you have a vitamin C deficiency – something which only few people in the West have.
References:
1) http://videnskab.dk/krop-sundhed/hvad-hjaelper-mod-forkoelelse
