Taking vitamin C supplements to prevent colds and other respiratory viruses does not have this effect, shows a Meta-analysis which investigated data from 29 studies. According to the researchers, vitamin C supplements do not prevent colds, but they can shorten their duration by about a day.
Vitamin C supplements – good or bad?
Vitamin C is found in abundance in fresh fruits and vegetables, but many people tend to turn to supplements without seeking medical advice, especially to prevent colds or relieve symptoms of a virus.
The meta-analysis included data from 29 studies involving more than 11,000 children and adults who took vitamin C supplements at a concentration of 1,000 milligrams or more over several years for preventive purposes.
Comparing these with a group of participants who took a placebo pill, the researchers concluded that vitamin C supplements taken daily and over a long period of time did not reduce the risk of viruses, but could shorten their duration by up to 10% .
In other words, if a cold lasts 10 days, with the help of vitamin C from supplements, its duration was reduced to 9 days. But only if the supplements are taken long-term, not if they are given occasionally or after the virus has set in.
Experts also noted that people who took vitamin C supplements, especially children, had milder symptoms.
Who should not take vitamin C supplements
Some vitamin C supplements contain more than 10 times the recommended daily dose – when the daily requirement is 100 milligrams -, which is why the excess is either eliminated in the urine or accumulates and can increase the risk of kidney stones, acid uric acid above normal, headache, dizziness or digestive disturbances such as nausea or diarrhoea.
Vitamin C supplements can be sold in the form of tablets, effervescent tablets, sprays or syrups, being easy to administer.
However, it is not advisable to take vitamin C supplements in excess, especially for people with certain medical conditions, such as thalassemia, hemochromatosis (excess iron in the body), a low level of the G6-PDH enzyme , sickle cell disease or sickle cell anemia.
Caution is also advised in taking vitamin C supplements in people with diabetes (they may increase blood sugar) or nephrolithiasis (kidney stones).
The best dietary sources of vitamin C
Vitamin C is found naturally in many fruits and vegetables, such as:
Citrus fruits: oranges (a medium orange contains about 80 milligrams of vitamin C), lemons, tangerines, clementines, grapefruit, pomelo, kiwi, pineapple, sweetie, tomatoes Mango Papaya Berries: strawberries, raspberries, blackberries, blueberries, blackcurrants Nectarines Peaches Watermelon Spinach Potatoes Tomatoes Bell peppers Parsley Red Cabbage Kale Cauliflower Broccoli
It is important to note that fruits and vegetables lose their vitamin C content when stored for long periods or cooked (in the case of vegetables). To get the optimal amount of nutrients they contain, eat them as soon as possible after buying them and limit their exposure to heat sources.
Sources:
Abdullah M, Jamil RT, Attia FN. Vitamin C (Ascorbic Acid) [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:
InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. Common colds: Does vitamin C keep you healthy? [Updated 2020 Oct 8]. Available from:
2023-10-04 07:30:53
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