Preventing the common cold through vitamin supplements, or even through dietary supplementation, is useless (and expensive) according to science.
During the season of change of season, with the recent arrival of autumn and in just a few months the winter cold, there are many who try by multiple means to prevent the common cold. And that is also glimpsed in searches and requests to Dr. Google, many of which include well-positioned results that continue to drag the usual myths: prevent the common cold based on vitamin C, vitamin A, zinc, or multivitamins in general.
The reality is that to prevent the common cold it is not necessary to take artificial supplementation, as long as a proper diet is carried out (something complex nowadays with the multitude of processed foods that invade supermarkets). What usually happens is that we use pharmacological supplementation because we eat badly, and we look for a "patch" in said supplementation to avoid diseases. Today we will review why supplements are not worth it, or eat foods rich in X or Y micronutrients (at least not excessively as a prevention), always according to science.
Vitamin C to prevent the common cold
Vitamin C, a micronutrient found in large amounts in fruits such as oranges, strawberries, kiwis, garlic, broccoli, parsley, onion, apples, pears, carrots, bananas, avocados, plums, blackberries, beef liver, or hot peppers, among many others, he is famous for having ascended to the point of a nutritional panacea for preventing the common cold. The lack of vitamin C can lead to a disease called scurvy, but it is very difficult to suffer a deficit of this vitamin in the Western world. Although it is more common in other areas of the planet such as the African continent and Southeast Asia.
When it comes to the common cold, vitamin C has never been shown to either prevent the common cold or speed its healing. The origin of the myth is due to the double Nobel laureate Linus Pauling (discoverer of the nature of chemical bonds and sickle cell anemia) and to an individual calling himself " Dr. Stone ", who was neither a doctor nor had knowledge in this matter.
The reality is that all the scientific societies of the time rejected Stone's findings, but his books sold like hotcakes. Still, we know that Pauling and Stone were wrong: Vitamin C does not help prevent the common cold, nor is it capable of curing any ailment in general. While some studies at the time claimed that vitamin C could shorten the time of a cold, supplementation with this vitamin is useless.
On the other hand, some recent studies have shown that vitamin C can improve other serious respiratory diseases such as asthma or tuberculosis, although the evidence in this regard is still weak and should continue to be investigated.
Vitamin A, D and E to prevent the common cold
On the other hand, although in this case it is a less named micronutrient, vitamin A is also advertised as an aid to prevent the common cold. This micronutrient is found in foods such as liver and derivatives, carrots, turnip greens, spinach, sweet potato, tomato, butter, cream, cured cheese, elver, eel, clams, clams and cockles.
In this case there is a small mess of concepts: the lack of vitamin A does increase the risk of respiratory infections, but its supplementation has not been shown to help prevent them.
What happens is that the lack of vitamin A, and malnutrition in general, increases the risk of infections of all kinds, especially respiratory and intestinal infections. On the other hand, scientific studies in this regard have focused on very specific areas of the world, such as India (where better nutrition has been shown to reduce infections), China, Indonesia or South Africa.
For example, according to a study of more than 600 infants by Chinese researchers, a lack of vitamin A and E has been shown to increase the risk of respiratory infections and diarrhea in children under 12 years of age. Likewise, another study focused on northern China reached a similar conclusion: a lack of vitamin A, D and E increases the risk of recurrent respiratory infections.
However, when it comes to vitamin A supplementation, an analysis from Brazil that looked at the results of five different studies in 8,000 households in the South American country over 20 years concluded that vitamin A supplementation would have little benefit. However, on the other hand, another study focused on China affirmed that the supplementation of vitamin A together with iron in preschool children would have benefits to prevent infections, as long as a joint supplement is made and not each isolated micronutrient.
For its part, another study from Indonesia affirmed that the combined supplementation of zinc and vitamin A does reduce the number of days of respiratory infection, but only in children in marginal conditions and malnutrition. However, another study from South Africa reached precisely the opposite conclusion, ensuring that vitamin A supplementation with zinc did not reduce diarrhea or respiratory infections in children from a rural population.
As we can see, supplements with multiple vitamins only show benefits in very specific cases. In fact, these are cases of populations that are known to be at risk of significant deficit or malnutrition (populations of Asia, Africa and South America). However, even in these cases that are at risk of malnutrition, there are studies that have even affirmed that not even such supplementation would have the desired benefit.
Thus, if we extrapolate this evidence to our territory (Spain and Western countries in general), supplementation would not only be useless at the health level, but a waste of money. Although our diet is saturated with ultra-processed foods, vitamin deficiencies are very rare, and supplementing our diet with more vitamins or trying to eat more for prevention would have no benefit. In fact, overindulging in supplementation, in certain cases, can even be harmful.
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