The effects of ascorbic acid and flavonoids on the occurrence of symptoms normally associated with the common cold

Abstract

A controlled study was made of the effects of natural orange juice, synthetic orange juice, and placebo in the prevention of the common cold; both natural and synthetic orange juices contained 80 mg of ascorbic acid daily. Three-hundred sixty-two healthy normal young adult volunteers, ages 17 to 25 years, were studied for 72 days with 97% of participants completing the trial. There was a 14 to 21% reduction in total symptoms due to the common cold in the supplemented groups that was statistically significant (P less than 0.05). Ascorbic acid supplementation also increased the number of "episode-free" subjects. However, the clinical usefulness of the results does not support prophylactic ascorbic acid supplements in the well-nourished adult. The results in this study with both natural and synthetic orange juice of physiological content of ascorbic acid, are similar to those obtained using a "megadose" of ascorbic acid.

Nutrition Discussion Forum

“…4. There is only a slight difference between the two male groups of Baird et al (1979) who were administered 80 mg vitamin C/d, and the difference is not in favour of orange juice. The number of cold episodes was ninety-one and ninety-three among the male subjects administered 80 mg/d in orange juice (n 62) and in synthetic drink (n 71) respectively, yielding RR = 0•89 (95 % CI: 0•67, 1•19) in favour of the synthetic drink.…”

“…Fourth, the intervention group in the study by Baird et al (1979) was a mixture of two sub-groups, one of which received a synthetic drink with 80 mg vitamin C, and the other received natural orange juice containing 80 mg vitamin C plus flavonoids etc. By combining these two sub-groups in his analysis, Hemilä fails to recognize the possible nonvitamin C-related effects of orange juice.…”

“…Hemilä himself clearly tended to discount the older 'poorly described' study of Glazebrook & Thomson (1942) which lacked a placebo group, and which in any case failed to demonstrate a significant benefit for the males. Thus the evidence of any benefit for British male subjects rests almost entirely on the studies of Charleston & Clegg (1972) and of Baird et al (1979), neither of which seems a very reliable candidate for inclusion.…”

“…The incidence rate was 6•2/year in the Charleston & Clegg (1972) male placebo group, but 11•2/year in the Baird et al (1979) male placebo group and 7•2/year in the Elwood et al (1976) female placebo group. The incidence was also higher in the large-scale trials by Ludvigsson et al (1977) and Pitt & Costrini (1979).…”

Effect of vitamin C on common cold: randomized controlled trial

“…Six, large randomized trials of normally nourished subjects in Western countries, whose supplementation period ranged from 2 to 9 months, revealed no effect of vitamin C on common cold incidence (Anderson et al, 1972;Karlowski et al, 1975;Elwood et al, 1976;Ludvigsson et al, 1977;Pitt and Costrini, 1979;Briggs, 1984). However, studies of specific groups, such as subjects under heavy acute physical stress (Hemila, 1996) or British males with extremely low levels of vitamin C intake (Glazebrook and Thomson, 1942;Charleston and Clegg, 1972;Clegg and Macdonald, 1975;Baird et al, 1979), revealed significant reduction in common cold incidence with vitamin C supplementation. In addition, studies have consistently found reduced duration or severity of the common cold with vitamin C supplementation (Hemila and Douglas, 1999).…”