Five Controlled Trials

[Part 1 of 4 in a series on Vitamin C and the Common Cold]

Linus Pauling became interested in ascorbic acid thanks to Dr. Irwin Stone, a biochemist from New York. After meeting Pauling in 1966 and hearing Pauling speak of his desire to live for an additional fifteen or twenty years, Dr. Stone sent him his own high-dose ascorbic acid regimen, which Pauling and his wife Ava Helen soon began to follow. After adhering to this program for several years, the Paulings observed a shared feeling of increased well-being and a striking decrease in the number of colds that they were contracting.

Linus Pauling was convinced that vitamin C was powerful enough to cure the common cold, but he was also aware that many authorities did not share his opinion.  He addressed this conflict in Chapter Five of his book Vitamin C and the Common Cold (1970) noting his desire to

resolve the apparent contradiction between the opinions expressed by authorities in nutrition and my own experience, which supported the widely held belief that ascorbic acid has value in decreasing the incidence of infection and ameliorating the severity of the common cold.

Pauling argued that ascorbic acid provides a minimal amount of protection against colds when taken in small amounts, but that the effect is proportionately greater when it is taken in much larger doses. According to Pauling, protection against colds becomes “nearly complete” when, shortly after the onset of a cold, one ingests four to ten grams of ascorbic acid per day. In support of his argument, Pauling cited five controlled trials conducted with various groups of people around the world.  These trials, he felt, supported his idea that health can be improved by adding more vitamin C to one’s diet.

Cowan, Diehl and Baker, 1942

The first study Pauling listed was an analysis of about 400 students at the University of Minnesota, conducted by Cowan, Diehl, and Baker during the winter of 1939-1940, and published in 1942 in the Journal of the American Medical Association. In this study, for twenty-eight weeks about half of the Minnesota students received 100 milligram tablets of vitamin C twice per day, while the other half received a placebo. The investigators concluded that the young adults who were already on a healthy diet were not greatly influenced by the 200 mg of vitamin C per day.  However, the study also yielded other important results.

First, the group receiving ascorbic acid throughout the twenty-eight week period experienced an average of 1.9 colds per person, with a 0.07 cold margin of error. Meanwhile, those in the placebo group reported an average of 2.2 colds per person, with a 0.08 margin of error. The investigators concluded that

the actual difference between the two groups during the year of the study amounts to 1/3 of a cold per person…[o]ne may therefore consider this as probably a significant difference, and vitamin C supplements to the diet may therefore be judged to give a slight advantage in reducing the number of colds experienced.

Pauling pointed out that this amounted to a 15% decrease in the quantity of colds per person. And although the investigators seemed to judge this a bordering-on-negligible amount, Pauling thought differently, wondering in his text if increasing the dosage to 400 mg of ascorbic acid per day would have decreased the colds twofold.

Another point in the Minnesota data that Pauling found compelling was the fact that of the 233 students participating in the ascorbic acid group, only 25 dropped out over the course of the study.  On the other hand, 39 students dropped out of the control group, which had started with 194 participants. Pauling drew the conclusion that a greater percentage of the students receiving ascorbic acid felt that they were benefiting from the study. Pauling likewise noted that the group which received vitamin C only missed an average of 1.1 days of school over the twenty-eight week study, while those who received the placebo lost an average of 1.6 school days.

Glazebrook and Thomson, 1942

In 1942 Glazebrook and Thomson published a similar study in the Journal of Hygiene, though this one focused on an institution of about 1,500 students in Scotland, where the students ranged in age from 15 to 20 years old. Glazebrook and Thomson’s group consumed a total dietary intake of only about 5 to 15 mg of ascorbic acid per student per day. This number was so low mainly because the school’s food was kept hot for two hours or more before serving, a practice which caused the served vegetables to lose much of their vitamin content.

In the Scottish survey, 335 students were given extra ascorbic acid – 200 mg per day for six months – while the remaining 1,100 served as a control. The ascorbic acid group recorded a 30.1 percent incidence of colds and tonsillitis, while the control group reported a 34.5 percent incidence. From these results, Pauling extrapolated that among the students who were given ascorbic acid, there were 13 percent fewer colds – a number close to the 15 percent decrease found in the Minnesota study.

The Scottish students who displayed more severe symptoms of colds or tonsillitis were admitted to Sick Quarters – 23.0 percent of the ascorbic acid group compared to 30.5 percent of the control group. This meant that 25 percent fewer students in the ascorbic acid group were admitted to Sick Quarters than were those in the control group.

Likewise, those receiving vitamin C also managed to stay out of the hospital: the average number of days spent in hospital due to infection for the control group was 5, versus 2.5 for the ascorbic acid group.  Drilling even deeper, there were 17 cases of pneumonia and 16 cases of acute rheumatism reported among the controls, while neither illness showed up in the ascorbic acid group.  Pauling used this data to emphasize the power of ascorbic acid in countering serious infections as well as the common cold.

Linus Pauling at an international vitamin symposium, Sao Paulo, Brazil, 1980.

Franz, Sands and Heyl, 1956

From there, Pauling briefly recounted an observation of 89 volunteer medical students and student nurses whose health was tracked for three months. The paper that resulted was published in a 1956 issue of the Journal of the American Medical Association by Franz, Sands, and Heyl. The study was constructed such that 44 of the students received 195 mg of ascorbic acid per day, while the remaining 45 received none.  In this instance, students in both groups experienced about the same number of colds, but the colds were judged to be less severe for the ascorbic acid group. It was concluded that this decreased severity and rapid improvement was “statistically significant at the 0.05 level.”

Wilson and Low, 1970

While each of the above studies and their results were relevant to Pauling’s case, Wilson and Low’s 1970 Acta Allergologica paper was of greater importance because it was a double-blind investigation. In this instance, neither the subjects – 103 students at a girls’ school in Ireland – nor the investigators evaluating the effects of the preparation knew which subjects had been given the placebo and which ones had been given vitamin C; that is, not until the study had reached its conclusion. As with the previous trials, the amount of 200 mg per day was used, but in the Wilson-Low group, 57 students received ascorbic acid while 46 received a placebo tablet over a period of three winter months.

Wilson and Low’s data indicated that ascorbic acid “reduced the incidence, duration, and severity of the symptoms of both toxic colds (sore throat, headache, fever, malaise) and catarrhal colds (cold in the head, cough, nasal obstruction, nasal discharge).” Symptoms of catarrhal colds lasted 8 days for the ascorbic acid group as opposed to 14 in the placebo group.

Pauling also noted that laboratory work indicated that the girls receiving ascorbic acid showed a higher concentration of ascorbic acid in the white blood cells than did the control group: the girls who had been receiving 200 mg of ascorbic acid once a day for 6 months had, on average, 60 micrograms of ascorbic acid present per hundred million cells, while those in the control group averaged 43 micrograms per hundred million cells. Pauling believed that “[t]his increase may be in part responsible for the increased resistance to infection.”

Ritzel, 1961

While these four studies seemed to show that about 200 mg of vitamin C daily can lessen the duration and symptoms of the common cold, Pauling needed to reinforce his hypothesis that “a somewhat larger intake of ascorbic acid provides somewhat greater protection.” To do so, Pauling turned to another double-blind study carried out in 1961 by the Swiss investigator Gunther Ritzel and published in Helvetica Medica Acta.

Unlike the rest of the literature cited by Pauling, Ritzel used 1000 mg of ascorbic acid, and noted a much greater effect than did the previous 200 mg studies. In his test of 279 skiers, Ritzel provided half of the subjects with 1000 mg of ascorbic acid per day, while the other half received a placebo. Among the vitamin C group, the data indicated a reduction of 61 percent in the number of days of illness from upper respiratory infections, and a 65 percent decrease in individual symptoms. Pauling was quick to note the substantial improvement in Ritzel’s group as compared to the 15 percent decrease brought about in the earlier studies by the daily ingestion of 200 mg of vitamin C. The data all seemed to provide solid evidence for Pauling’s basic rule of thumb:  when it comes to the common cold, the more vitamin C the better.

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