Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. Effect of raw garlic vs commercial garlic supplements on plasma lipid concentrations in adults with moderate hypercholesterolemia: a randomized clinical trial. A randomized controlled trial of vitamin C in the prevention and amelioration of the common cold. Effects of garlic coated tablets in peripheral arterial occlusive disease. Effect of vitamin C on common cold: randomized controlled trial. Efficacy of Echinacea purpurea in patients with a common cold. A placebo-controlled, randomised, double-blind clinical trial. A trial of ascorbic acid in the treatment of the common cold. Two randomized controlled trials of virucidal nasal tissues in the prevention of natural upper respiratory infections. Preventing the common cold with a vitamin C supplement: a double-blind, placebo-controlled survey.
One hundred forty-six volunteers were randomized to receive a placebo or an allicin-containing garlic supplement, one capsule daily, over a 12-week period between November and February. They used a five-point scale to assess their health and recorded any common cold infections and symptoms in a daily diary. The active-treatment group had significantly fewer colds than the placebo group (24 vs 65, P < .001). The placebo group, in contrast, recorded significantly more days challenged virally (366 vs 111, P < .05) and a significantly longer duration of symptoms (5.01 vs 1.52 days, P < .001). Consequently, volunteers in the active group were less likely to get a cold and recovered faster if infected. Volunteers taking placebo were much more likely to get more than one cold over the treatment period. An allicin-containing supplement can prevent attack by the common cold virus. Garlic is widely promoted as a cholesterol-lowering agent, but efficacy studies have produced conflicting results. Garlic supplements differ in bioavailability of key phytochemicals. We evaluated the effect of raw garlic and 2 commonly used garlic supplements on cholesterol concentrations in adults with moderate hypercholesterolemia.
                In this parallel-design trial, 192 adults with low-density lipoprotein cholesterol (LDL-C) concentrations of 130 to 190 mg/dL (3.36-4.91 mmol/L) were randomly assigned to 1 of the following 4 treatment arms: raw garlic, powdered garlic supplement, aged garlic extract supplement, or placebo. Garlic product doses equivalent to an average-sized garlic clove were consumed 6 d/wk for 6 months. The primary study outcome was LDL-C concentration. Fasting plasma lipid concentrations were assessed monthly. Extensive chemical characterization of study materials was conducted throughout the trial.
                Retention was 87% to 90% in all 4 treatment arms, and chemical stability of study materials was high throughout the trial. There were no statistically significant effects of the 3 forms of garlic on LDL-C concentrations. The 6-month mean (SD) changes in LDL-C concentrations were +0.4 (19.3) mg/dL (+0.01 [0.50] mmol/L), +3.2 (17.2) mg/dL (+0.08 [0.44] mmol/L), +0.2 (17.8) mg/dL (+0.005 [0.46] mmol/L), and -3.9 (16.5) mg/dL (-0.10 [0.43] mmol/L) for raw garlic, powdered supplement, aged extract supplement, and placebo, respectively. There were no statistically significant effects on high-density lipoprotein cholesterol, triglyceride levels, or total cholesterol-high-density lipoprotein cholesterol ratio.
                None of the forms of garlic used in this study, including raw garlic, when given at an approximate dose of a 4-g clove per day, 6 d/wk for 6 months, had statistically or clinically significant effects on LDL-C or other plasma lipid concentrations in adults with moderate hypercholesterolemia. A randomized controlled trial of the effect of 1 g ascorbic acid per day in the prevention of the common cold was conducted on 688 adult women. There is evidence of a small reduction by vitamin C in the mean number of chest colds, but no evidence of any effect on simple colds. The existence of a subgroup of vulnerable women in the community who benefit from vitamin C was considered but further examination of the data gives no support to this conclusion. For the first time, a weak clinical efficacy of a 12-week therapy with garlic powder (daily dose, 800 mg) is demonstrated in patients with peripheral arterial occlusive disease stage II. The increase in walking distance in the verum group by 46 m (from 161.0 +/- 65.1 to 207.1 +/- 85.0 m) was significantly higher (P < 0.05) than in the placebo group (by 31 m, from 172.0 +/- 60.9 to 203.1 +/- 72.8). Both groups received physical therapy twice a week. The diastolic blood pressure, spontaneous thrombocyte aggregation, plasma viscosity, and cholesterol concentration also decreased significantly. Body weight was maintained. It is quite interesting that the garlic-specific increase in walking distance did not appear to occur until the 5th week of treatment, connected with a simultaneous decrease in spontaneous thrombocyte aggregation. Therefore, garlic may be an appropriate agent especially for the long-term treatment of an incipient intermittent claudication. To investigate the relationship between the common cold and vitamin C supplementation.
                A double-blind, 5-year randomized controlled trial.
                A village in Akita prefecture, one of the regions in Japan with the highest mortality from gastric cancer.
                Participants in annual screening programs for circulatory diseases conducted under the National Health and Welfare Services Law for the Aged, and diagnosed as having atrophic gastritis. Of the 439 eligible subjects, 144 and 161 were assigned to receive 50 or 500 mg of vitamin C, respectively, after protocol amendment. During the supplementation phase, 61 dropped out, and 244 completed the trial. Intervention: Daily vitamin C supplementation of 50 mg (low-dose group) or 500 mg (high-dose group).
                Total number of common colds (per 1000 person-months) was 21.3 and 17.1 for the low- and high-dose groups, respectively. After adjustment for several factors, the relative risks (95% confidence interval (CI)) of suffering from a common cold three or more times during the survey period was 0.34 (0.12-0.97) for the high-dose group. No apparent reduction was seen for the severity and duration of the common cold.
                A randomized, controlled 5-year trial suggests that vitamin C supplementation significantly reduces the frequency of the common cold but had no apparent effect on the duration or severity of the common cold. However, considering several limitations due to protocol amendment, the findings should be interpreted with caution. Common colds are one of the most frequent acute illnesses with major economical impact. Echinaceae purpureae herba (Echinacin, EC31J0) has shown promising results in the relief of common cold symptoms and the time taken to improvement compared to placebo. This study was aimed to confirm these findings by performing a randomised, double-blind, placebo-controlled clinical trial. A total of 80 adult male or female patients with first signs of a cold were recruited. The number of days of illness with a complete picture of the common cold (defined by the modified Jackson score of at least 5 points and experience of rhinorrhea and/or a subjective sensation of having a cold) was the primary end-point. In the verum group the median time of illness was 6.0 days compared to 9.0 days in the placebo group, assigning zero time for patients without a complete picture (one-sided p = 0.0112). EC31J0 was well tolerated and clinically effective in alleviating symptoms more rapidly than placebo in patients with a common cold. A randomised controlled trial was carried out to study the effect of 10 g of ascorbic acid taken during the first 2 1/2 days on the symptoms of the common cold. Altogether 1524 volunteers were recruited from a number of working groups in different parts of the country; 482 developed colds. There was no evidence that upper respiratory or general constitutional symptoms were alleviated by ascorbic acid. Among the men who had any colds at all, significantly fewer on active than on placebo treatment had two or more colds; however, this effect was not seen in women. Ascorbic acid is of no value in the treatment of the common cold; its preventive effect, if any, is not such as to justify advising its general use as a prophylactic measure. Two six-month randomized, controlled double-blind trials of the efficacy of virucidal nasal tissues in the prevention of natural colds were conducted in Charlottesville, Virginia, between 1983 and 1986. Tissues impregnated with malic and citric acids and sodium lauryl sulfate were used in both trials. Placebo tissues contained saccharin in the first trial and a mixture including succinic acid in the second. A total of 186 families were evaluable after completion of trial I, and 98 families were evaluable in trial II. The antiviral tissues were associated with 14 and 5% relative reductions in the overall rate of colds in the first and second trials, respectively. In the first study, this appeared to be due to an appropriate fall in secondary illnesses with a relative reduction in the ratio of secondary to primary illnesses of 32%. In trial II, however, the small and statistically insignificant reduction was primarily due to a drop in the rate of primary illness (which cannot be attributed to tissue efficacy), and the ratio of secondary to primary illness was actually 5% higher in the group with active tissues than in the placebo group. We conclude that when rigorously used in a study protocol, virucidal tissues may offer a modest reduction of secondary colds in the home, but for reasons currently unknown, do not have a major effect on the overall rate of colds. One hundred sixty-eight volunteers were randomized to receive a placebo or a vitamin C supplement, two tablets daily, over a 60-day period between November and February. They used a five-point scale to assess their health and recorded any common cold infections and symptoms in a daily diary. Compared with the placebo group, the active-treatment group had significantly fewer colds (37 vs 50, P<.05), fewer days challenged virally (85 vs 178), and a significantly shorter duration of severe symptoms (1.8 vs 3.1 days, P<.03). Consequently, volunteers in the active group were less likely to get a cold and recovered faster if infected. Few side effects occurred with the active treatment, and volunteers reported greatly increased satisfaction with the study supplement compared with any previous form of vitamin C. This well-tolerated vitamin C supplement may prevent the common cold and shorten the duration of symptoms. Volunteers were generally impressed by the protection afforded them during the winter months and the general acceptability of the study medication.
There is insufficient clinical trial evidence regarding the effects of garlic in preventing or treating the common cold. A single trial suggested that garlic may prevent occurrences of the common cold but more studies are needed to validate this finding. Claims of effectiveness appear to rely largely on poor-quality evidence.