Vitamin C

The RDA for vitamin C is between 45 and 60 mg per day. The writings of Linus Pauling have popularized the use of vitamin C as a prophylactic and therapeutic agent for the common cold [25]. The nutritional value of a vitamin ingested at more than 10 times its RDA begs the question of whether the vitamin is nutritional or pharmacologic. A comprehensive meta-analysis has been published [26] which finds that huge doses of vitamin C have a minimal effect on reducing cold symptoms. No effect on cold prevention could be found unless groups undergoing hypothermic stress were studied.

There is a published study which supplemented British patients over the age of 65 with a placebo or 200 mg of vitamin C if they were admitted to hospital with bronchitis or pneumonia [27]. The patients were followed for 4 weeks. If patients who died were excluded from the analysis, the study showed that vitamin C administration lessened the symptom score of surviving patients. Only one of the six deaths in the study occurred in a vitamin C recipient, but the sample size was too small (n = 57) to show significance.

Cranberry juice

Many people believe that drinking cranberry juice will treat or prevent urinary tract infections. There is evidence that cranberry juice contains anti-adhesive molecules which could interfere with bacterial virulence mechanisms [28]. Cranberry juice (300 ml/day) or a colored drink containing no cranberry products were provided to female residents of a long-term care facility in Boston [29]. Monthly urine samples were analyzed. At one month, the percentage of urine samples with more than 100,000 CFU/ml of urine was identical whether or not cranberry juice was ingested. After one month, there was a consistent decrease in high-grade bacteriuria in the cranberry juice drinkers. The calculated relative risk for bacteriuria with pyuria for cranberry drinkers was 0.42 (p = 0.0004). Antibiotic use for UTI was almost halved in those drinking cranberry juice. In this study, the distinction between UTI prevention and treatment is unclear, but its ability to obviate the use of antibiotics is significant.

A Canadian study randomized 150 sexually active women who had = 2 UTIs in the previous year into three groups: 1) 250 ml of diluted pineapple juice (colored red) thrice daily and a placebo tablet twice daily; 2) A concentrated cranberry extract tablet twice daily and placebo juice; 3) 250 ml of cranberry juice thrice daily and a placebo tablet [30]. The study continued for a year. Symptomatic infections were treated with antibiotics for 3 days and the prophylaxis restarted. The placebo group showed 32% of entrants with at least one UTI during the year of study. The tablet group had 18% with at least one infection and the cranberry juice group had 20%. The difference between the tablet or juice groups and placebo was significant (p < 0.05). The mean number of UTIs per year was approximately halved by the use of a cranberry product.

The daily ingestion of cranberry juice concentrate or a placebo did not affect bacteriuria rates in children requiring intermittent catheterization [31].

There is sufficient reason based on these two positive studies and others reviewed by Raz et al [29] to recommend a cranberry product to women with recurrent UTIs.