Zinc pills, garlic capsules … there are many home remedies to deal with the common cold, but is there any scientific evidence that they actually work?
There are few experiences as universal as suffering from a cold. And although there are about 200 different viruses that cause this, it seems like there are almost as many home remedies to fight it.
But any of these jobs?
Behind all home remedies is the idea that they help to strengthen the immune system.
When a virus enters our body, it faces two defense systems: the innate immune system that tries to get rid of the invading cells and the adaptive system, which targets specific pathogens with which the body has already had contact and against them. which creates immunity by producing cells capable of fighting them if they return.
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That is why we tend to suffer from chicken pox only once in a lifetime, while the common cold – which changes appearance by passing from one person to another, confusing our memory cells – is something we can experience dozens of times
It is well established that both lifestyle and diet affect the strength of our immune system.
But as our immune system is limited only when we have a vitamin or mineral deficit, supplementing our diet with foods that are considered effective against the flu will make little difference if we already have a relatively good diet, according to Charles Bangham, head of diet. Division of Infectious Diseases, Imperial College of London.
"Only if you have a deficiency of a vital nutrient, such as vitamins, zinc or iron, will it be very helpful to receive a supplement for that specific element, but if you have a balanced diet, add more of these things not. , he says.
The solution of supplements
Despite this, some studies that ask about the common cold remedies have found that they can make a difference.
The vast majority of this research focuses on supplements, rather than food: in fact, no reliable study has been done on whether a popular remedy like chicken soup really makes a difference.
However, a supplement that can help is a popular home remedy: garlic.
In a small study, 146 healthy adults received a placebo or a daily garlic supplement for 12 weeks during the winter.
The placebo group contracted 65 colds that resulted in 366 days of medical leave, while those taking the garlic supplement suffered only 24 colds, which totaled a total of 111 days of medical leave.
Another supplement that many people resort to when they experience the symptoms of the cold is vitamin C. Some research suggests that it can also be useful, though not as much as you might think.
An analysis of 29 studies on vitamin C supplementation has not found that these have significantly reduced the risk of suffering from a cold or relieving its symptoms.
However, it was found that there was a reduction in the duration of colds of 14% in the case of children and 8% in adults. The researchers concluded that since these are low-risk supplements, it was worth trying to see if they could help.
Orange juice may be less useful: there is strong evidence that it helps prevent the cold, alleviate its symptoms, or reduce its duration.
This is because it does not contain enough high doses of vitamin C to have the same impact as daily supplements, according to Harri Hemilä, a researcher on public health issues at the University of Helsinki and author of the analysis of studies in the field. Vitamin C.
A small bottle of orange juice made with fresh juice has about 72 mg of vitamin C, according to the United States Department of Agriculture. This is more than the recommended minimum daily dose, but much less than many supplements contain.
Then there is zinc. An analysis of the effectiveness of taking zinc pills daily to cope with the common cold found that they reduced the time spent by patients with nasal obstruction or drip by a third, and reduced sneezing and cough by 22%. the half.
The study concluded that if you started taking it within 24 hours after the first symptoms appear, a daily dose of 80 milligrams of zinc may help treat the common cold.
However, Hemilä believes that it is more accurate to study the complete recovery of a cold than to measure the duration of symptoms. Their study of 199 patients with the common cold found that those who received daily doses of zinc recovered three times faster.
Scientists often say it is better to get vitamins and minerals through food instead of supplements, although they often point out that in the case of vitamin C it is easier to get higher doses with supplements. .
In the case of zinc, however, it works best upside down. To be effective against the cold, zinc should be consumed in tablets and not in ordinary tablets or foods rich in that mineral, notes Hemilä.
"Zinc pills dissolve slowly in the throat region and the effect of zinc is local. We do not know what the biochemical mechanism is for this effect, but studies indicate that when zinc pills are effective, they are great pills. dissolve up to 30 minutes in the mouth, "he says.
Often a complication is that the researchers did not investigate whether people already had deficiencies in something like vitamin C or zinc before starting treatment.
So any benefit against the cold could be due to the fact that in taking the supplement, some participants would be correcting a deficiency, rather than being the supplement making a difference in healthy people.
Another difficulty is the power of placebos. Of course, many studies, such as garlic supplements, have a control group that receives a placebo, so it is known that the effect achieved is not due solely to the placebo effect.
But if we swear that something about which there is no scientific evidence or is limited, such as chicken soup or orange juice, actually heals us, it may be due to the placebo effect.
Studies have shown that placebos are an effective way to relieve many symptoms, from pain to irritable bowel syndrome, although the reasons for this are still not fully understood. And when it comes to vitamin C or chicken soup, it may be that the placebo effect helps us overcome the cold.
One study found that people who believed in the supposed cold-fighting properties of the medicinal herb echinacea experienced the disease less severely and for shorter periods while taking daily doses of that herb than those who did not believe in it.
However, earlier studies in which participants did not know they were receiving doses from that plant did not experience improvement in cold symptoms.
It also works in the opposite direction. For a long time it was believed that milk worsens the production of mucus when we have a cold, but this turned out to be false. However, one study found that people who believed that milk is the cause of mucus reported more respiratory problems after taking it.
While placebos are usually administered by doctors during clinical trials, the placebo effect of home remedies comes from our daily lives, notes Felicity Bishop, an associate professor of health psychology at the University of Southampton.
"Studies show that the power of placebo comes from the relationship of trust between patients and healthcare professionals, someone who gives a dedicated attention and can offer treatments with confidence," he says. "And this is similar to what parents do when we are young, it's the kind of relationship that matters, not who that person is."
As with trusted friends and family members, the placebo effect can be enhanced by the way the food is marketed, according to Bishop.
The good news is that knowing that some remedies are placebos will not necessarily prevent them from alleviating our symptoms.
"Even when a doctor tells a patient that something is a placebo, but that its use has helped some people, that can make the person feel better," he says.
Another effect may be the comfort induced by these foods. Nutritionist Sarah Schenker says the comfort of having chicken soup, for example, could help someone with a cold feel a little better.
More than the amount of vitamin C we consume, the chances of getting rid of the cold in the winter depend largely on each person, including how much we believe in placebos, but also depending on our genes.
"Genetics makes some people particularly susceptible to certain diseases.It is much more important to realize that we are different from one another: when some people have a cold, they do not even notice it, while others suffer from severe symptoms. much bigger ".
For most people with a healthy immune system, we can do little more than rely on the power of placebos to overcome winter viruses … However, taking some zinc or garlic supplements can also help.
You can read the original version of this note at English.