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Vitamin C and the Common Cold
By Kelsey Linden
March 4, 2009
Vitamin C is a well-known nutrient that is displayed on nutrition labels, talked about in advertisements, and found in dietary supplements. While many may be unaware of its true effects, there is a common understanding that vitamin C is linked to the immune system. With the numerous advertisements for products that contain vitamin C and their benefit in keeping someone healthy and free from illness, it is no wonder that there is a common belief that vitamin C can help prevent and cure the common cold. When people get a cold, they are often told to drink orange juice, take vitamin C supplements, or increase their consumption of vitamin C rich foods. While most people willingly adhere to this belief, is there really any evidence that increasing vitamin C intake will keep someone from catching a cold, or to help cure a cold once it is contracted? From recent studies, the evidence is lacking, and most scientists and doctors alike have come to the conclusion that vitamin C does little to aid in the prevention or cure of the common cold.
Basic Facts of Vitamin C
Vitamin C is the most popular dietary supplement in the U.S. and studies reveal that over 40% of older individuals in the U.S. take vitamin C supplements (http://www.whfoods.com/genpage.php?tname=nutrient&dbid=109). This large proportion of the population taking vitamin C supplements demonstrates the rightly placed value on this critical vitamin for humans. According to William McGee (2007), vitamin C, also referred to as ascorbic acid, is a water-soluble nutrient that is vital to many basic functions of the human body. Unlike many other animals, humans cannot make vitamin C themselves and also do not store the vitamin in the body when it is not needed; therefore, humans must take in a continuous supply through their diet. Luckily, Vitamin C is contained in many foods, especially fruits and vegetables. Examples of foods rich in vitamin C include green peppers, citrus fruits and juices, strawberries, tomatoes, broccoli, cantaloupe and many other common fruits and vegetables (http://www.nlm.nih.gov/medlineplus/ency/article/002404.htm). On the market today there are numerous vitamin C dietary supplements and multivitamins that contain this necessary nutrient, making it easy to consume the recommended intake.
Vitamin C serves mainly a protective role in the body by helping rebuild tissue and by protecting against diseases (http://www.whfoods.com/genpage.php?tname=nutrient&dbid=109). According to the MedlinePlus Medical Encyclopedia, vitamin C is required for the growth and repair of tissues in all parts of the human body, as well as being essential for the healing of wounds and the repair and maintenance of cartilage, bones and teeth. Vitamin C is necessary to form collagen, a protein that is used to make skin, scar tissue, tendons, ligaments, and blood vessels. In addition, Vitamin C is an antioxidant that helps block damage from free radicals throughout the body (http://www.nlm.nih.gov/medlineplus/ency/article/002404.htm). Without this nutrient, the human body would be unable to properly heal wounds and would be more open to contracting diseases and infections.
Vitamin C was first discovered in its use as the cure to the disease scurvy. According to Hughes (2008), “The early history of vitamin C cannot readily be separated from that of the demise of scurvy.” In the early 19th century, James Lind first showed the idea that citrus fruits, all containing vitamin C, could cure the disease. It wasn’t until later on that scientists and nutritionists alike accepted that vitamin C was not just a cure but also a necessary part of one’s diet. In the mid-1970’s, a scientist by the name of Linus Pauling first linked vitamin C to the prevention and cure of colds as well as other diseases. His work describing the benefit of vitamin C caught on to the public and began the widespread idea that vitamin C can prevent and cure a common cold.
Daily Intake Recommendations
The recommended daily intake of vitamin C varies from person to person depending on age, gender and physical condition. The recommended daily intake, published by the U.S. Food and Nutrition Board of the institute of Medicine, for men older than 18 years old is 90 milligrams per day; for women over 18 is 75 milligrams per day. However, pregnant and breastfeeding women tend to need higher amounts of vitamin C. For example, pregnant women are recommended to consume 85 mg/day, while breastfeeding women need as much as 120 mg/day. Also, some experts recommend a dosage to smokers of up to 35 mg higher than the normal recommendation. For children, the Adequate Intakes and U.S. Dietary Reference Intakes for infants age 0-6 months old of vitamin C are 40 mg/day. For infants 7-12 months old is 50 mg/day. As children grow older their recommended intake changes. For a child 1-3 years old the recommended intake is only 15 mg/day but when a child is 4-8 years old the DRI increases to 65 mg/day, and then once again the DRI decreases to 45 mg/day for children 9-13 years old. For children 14-18 years old, gender becomes an important factor in the DRI. For females ages 14-18 the DRI is 65 mg/day but for males of the same age it is 75 mg/day (http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-vitaminc.html). While the recommendations vary with age and gender, most amounts of vitamin C intake are safe and it is easy to consume the recommended amounts through eating a well-balanced diet. However, there are such things as vitamin C deficiency and toxicity, both of which have unpleasant and potentially harmful symptoms.
Vitamin C deficiency occurs from a lack of the nutrient and can cause bleeding gums, dry and splitting hair, poor wound healing, rough and dry skin, easy bruising, weakened tooth enamel, decreased ability to fight infection and swollen or painful joints. In extreme cases, deficiency can lead to a disease called scurvy, which mainly affects older, malnourished adults. There is not a serious threat of scurvy in humans who eat a normal well-balanced diet. Vitamin C toxicity occurs from too much intake of the nutrient, normally through the overuse of supplements and vitamin pills. Toxicity is very rare because the body cannot store vitamin C; however, intakes greater than 2,000 mg/day can lead to an upset stomach and diarrhea (http://www.nlm.nih.gov/medlineplus/ency/article/002404.htm). In one case study by McHugh, Graber and Freebairn (2008), a 72-year-old male died from “the development of renal failure in association with use of high-dose vitamin C”. Due to the man’s over consumption of vitamin C and his failure to tell his physician of his intake, the man died from the effects of the toxicity. This is a rare case that does not occur very often; however, it does highlight the dangers of overusing vitamin C supplements.
The Common Cold: An Overview
The first symptoms of a common cold are well-known throughout the U.S., such as sneezing, scratchy throat, and runny nose, as is evident by the frequency of doctor visits and missed days from school and work due to these symptoms. According to the National Institute of Allergy and Infectious Diseases (2007), people in the U.S. suffer 1 billion colds each year and these colds are especially prevalent in young children, who are estimated to have about 6-10 colds every year. Most colds occur during the fall and winter months and are usually mild, with symptoms lasting 1-2 weeks long. There are over 200 different viruses that can cause a cold, with the most common family of viruses being the rhinoviruses that cause an estimated 30-35 percent of all adult colds. There are some viruses that can cause more severe symptoms and infections but most seldom produce serious illnesses. Colds can be transmitted through the touching of infected surfaces and then touching your eyes or nose, or through inhaling drops of mucus full of cold germs from the air. Symptoms include mucus build up in the nose, swelling of the sinuses, sore throat, sneezing, cough, headache, and even a slight fever. Colds can be passed very easily among people, and are therefore difficult to prevent. Doctors recommend washing hands often, avoiding people with colds, and avoiding touching the eyes and nose. Colds can occasionally lead to complications such as bacterial infections in the middle ear or sinuses, which require antibiotics to treat; however, most people recover from a cold in as short as a week and do not require any form of medication (http://www3.niaid.nih.gov/topics/commonCold/overview.htm).
Common Cold and Vitamin C: The Connection
In the 1970’s, a scientist by the name of Linus Pauling published a book called “Vitamin C and the Common Cold” where he wrote about his findings of vitamin C as a beneficiary agent in preventing the common cold. He states, “I reached the conclusion that ascorbic acid, taken in the proper amounts, decreases the incidence of colds and related infections, and also decreases the severity of individual colds.” Pauling used the results of four double blind studies from four different investigators that all compared the effects of the intake of more than 100mg of vitamin C per day with a placebo administered to subjects who had not yet caught cold and were subjected to cold viruses in an ordinary way. Pauling compared the results of the four studies to conclude that ascorbic acid (vitamin C) does have an effect in the incidence and severity of a cold in comparison to a placebo. Pauling’s book was the first major publishing of this conclusion and further helped instill the belief that vitamin C is in fact beneficial in preventing the common cold (Pauling, 1971).
Other influences to this common belief include the numerous advertisements for supplements, foods and fortified drinks that all contain vitamin C. There is even such a thing as the Vitamin C Foundation, whose website proclaims, “Surefire cures for the common cold and the flu!” as the main headline (http://www.vitamincfoundation.org/surefire.htm). Recently, it seems as if every drink is now vitamin fortified or enhanced in some way, from sports drinks to soda to even vitamin-enhanced water. Everywhere consumers turn there are advertisements aimed towards the belief that vitamin C will help prevent and cure illnesses when in reality there is little to no basis for this belief in relation to the common cold.
Over the last 60 years, research has been conducted to examine the effects of vitamin C in preventing and curing the common cold. According to Smith (2007), a study was conducted by researchers to discover whether taking 200mg or more of vitamin C daily could reduce the frequency, duration or severity of a cold. After reviewing over 60 years of clinical research, the conclusion stated: “When taken after a cold starts, vitamin C supplements do not make a cold shorter or less severe. When taken daily, vitamin C very slightly shortened cold duration—by 8% in adults and by 14% in children.” This means that the average adult who suffers a cold for 12 days will suffer a cold for 11 days with the daily intake of vitamin C (http://www.webmd.com/cold-and-flu/cold-guide/vitamin-c-for-common-cold).
According to Hemila, Chalker, Treacy and Douglas (2007), data was collected to explore the effects of vitamin C on the incidence, severity and duration of the common cold when used as a continuous prophylaxis or after the onset of cold symptoms. The study looked at trials conducted with a dose of 200 mg or more of daily vitamin C intake and where a placebo was used for comparison. The incidence of colds was defined as the proportion of participants experiencing one or more colds during the study period. The duration was the mean days of illness and the severity was assessed by the number of days confined indoors, off work or school, or by symptom severity scores. The researchers reviewed 29 trial comparisons involved 11,077 participants to calculate the pooled relative risk as .96 of developing a cold while taking prophylaxis. A subgroup of trials involved 642 participants exposed to extreme conditions, including marathon runners, skiers and soldiers on sub-arctic exercises revealed a pooled relative risk of .50 while taking prophylaxis. As for the duration of a cold while taking vitamin C, thirty comparisons involving 9,676 respiratory episodes contributed to the observance of a consistent benefit. There was an 8% reduction in cold duration for adults and 13.6% reduction in cold duration for children. Researchers also looked at the effects on the severity of colds while on prophylaxis, and fifteen trial comparisons involving 7,045 respiratory episodes revealed inconsistent results depending on the form of measurement of the severity of the illness. The researchers also compared trials where the participants began taking vitamin C only after the onset of symptoms. This seven trial comparison involving 3,294 respiratory episodes revealed no significant difference between the participants taking vitamin C and those taking the placebo. The researchers concluded “the failure of vitamin C supplementation to reduce the incidence of colds in the normal population indicates that routine mega-dose prophylaxis is not rationally justified for community use. But evidence suggests that it could be justified for people exposed to brief periods of severe physical exercise or cold environments.”
In another study done by Anderson, Suranyi and Beaton (1974), 2,349 volunteers participated in a double-blind trial to assess the effects of large doses of vitamin C on the incidence and severity of the common cold. There were eight treatment regiments, three of which were prophylactic-only, two therapeutic-only, one combination, and two placebo control groups. The prophylactic-only groups took daily doses of vitamin C, the therapeutic groups took a high dose only on the first day of illness, and the combination group took a daily dose as well as a high dose on the first day of illness. The results of the study showed a small effect from both the prophylactic and therapeutic groups and a larger effect in the reduction of severity from the combination group. However, between the three different prophylactic groups, all of which took different daily doses of vitamin C, there was no difference in the frequency of illness, revealing that larger doses of vitamin C are not beneficial except possibly at the first onset of the illness when a larger dose of vitamin C may slightly reduce the severity and duration of symptoms.
Based on the available research, studies, and reviews, it can be concluded that the common belief that vitamin C helps in the prevention and reduction of the common cold is not accurate. While there does seem to be evidence that the daily intake of vitamin C will slightly reduce the duration of the common cold, and that upon the arrival of symptoms a larger dose of vitamin C could be beneficial, the evidence is lacking for the normal population. Studies reveal that the intake of vitamin C can reduce the incidence of the common cold in people exposed to extreme physical conditions such as marathon runners and skiers. However, for the normal population, increased intake of vitamin C will not be as beneficiary in fighting a cold.
According to the National Institute of Allergy and Infectious Diseases, since there is no known cure for the common cold, proper treatment involves getting lots of rest, drinking plenty of fluids, gargling with warm salt water to relieve a sore throat, and taking Tylenol for a headache or fever. Nonprescription cold remedies, including decongestants and cough suppressants, may relieve some cold symptoms but can also have side effects, such as drowsiness or an upset stomach so should be taken with care (http://www3.niaid.nih.gov/topics/commonCold/treatment.htm).
The common cold lives true to its name of “common” as it infects millions each year, and while people may try many different remedies to cure their symptoms, taking vitamin C as treatment will not likely be any more beneficial than other remedies such as resting in bed. However, vitamin C is an important nutrient that the body needs to function properly and should be a part of the well-balanced diet.
Anderson, T. W., Suranyi, G., & Beaton, G. H. (1974, July 6). The effect of winter illness of large doses of vitamin C. Canadian Medical Association Journal, 111(1), 31-36. Retrieved January, 2009, from PubMed database. (PMC1947567)
Blandino, D. A., M.D., & Simasek, M., M.D. (2007, February 15). Treatment of the Common Cold. American Academy of Family Physicians. Retrieved from http://www.aafp.org/afp/20070215/515.html
Common cold. (2007, December 7). National Institute of allergy and infectious diseases. Retrieved January 20, 2009, from National Institutes of Health Web site: http://www3.niaid.nih.gov/topics/commonCold/overview.htm
Hemila, H., Chalker, E., Treacy, B., & Douglas, B. (2007, July 18). Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews, (3), art. no.: cd000980. Retrieved January, 2009. doi:10.1002/14651858.CD000980.pub3
Hughes, R. E. (2000, October). Vitamin C. In K. F. Kiple & K. C. Ornelas (Eds.), The Cambridge World History of Food (Vol. 2, iv.a.3.). Cambridge University Press. Retrieved January, 2009, from http://www.cambridge.org/us/books/kiple/introduction1.htm
Mateljan, G. (n.d.). Vitamin C. In The world’s healthiest foods. Retrieved January 20, 2009, from George Mateljan Foundation Web site: http://www.whfoods.com/genpage.php?tname=nutrient&dbid=109
McGee, W., M.D. (2007, January 2). Vitamin C. In Medical Encyclopedia. Retrieved January 20, 2009, from Medline Plus Web site: http://www.nlm.nih.gov/medlineplus/ency/article/002404.htm
McHugh, G., Graber, M., & Freebairn, R. (2008, July). Fatal vitamin C-associated acute renal failure. Anasthesia and Intensive Care, 36(4), 585(4). Retrieved from Health Reference Center Academic via Gale database.
Pauling, L. (1971, November). The Significance of the evidence about ascorbic acid and the common cold. Proceedings of the National Academy of Sciences of the USA, 68(11), 78-81. Retrieved January 20, 2009, from PubMed database. (PMC389499)
Smith, M. W., MD. (2007, December 18). Vitamin C for the common cold. In Cold guide. Retrieved January 29, 2009, from WebMD Web site: http://www.webmd.com/cold-and-flu/cold-guide/vitamin-c-for-common-cold
Surefire cures for the common cold or the flu. (2004, February). Retrieved January 29, 2009, from Vitamin C Foundation Web site: http://www.vitamincfoundation.org/surefire.htm
Vitamin C (ascorbic acid). (2008, March 1). Medline Plus. Retrieved January 20, 2009, from Natural Standard Research Collaboration Web site: http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-vitaminc.html
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