Posted on Sun, 29 Apr 12
A host of natural medicines are sold for cold and flu relief but not all of them work. Here are 5 natural supplements with high quality evidence from human clinical studies that do.
1. Vitamin C
Doses of 1000-2000 mg of vitamin C per day when you get a cold have been shown to shorten your time to recovery, and 500 mg per day works well as a preventative (1,2).
2. Garlic extract
A garlic extract containing allicin (a key active phytonutrient garlic) when taken over the winter months reduced number of colds (24 vs 65 for placebo) and sped up recovery time (1.52 vs 5.01 days for placebo) in a clinical study of over 350 people (3).
Elderberry extract (trade name Sambucol) has been shown to significantly improve flu symptoms and speed up time to recovery compared to placebo in two studies at a typical dose of 15 ml daily (4,5).
The herbal medicine Echinacea (purpurea and angustifola) has been shown to reduce cold symptoms by 58% and duration by 1.4 days across a number of studies and may also improve overall wellbeing (6,7). Recommended doses are 3-6 ml of liquid extract, and up to 10-20 ml at the onset of symptoms and continued for 7-14 days (8).
Taking zinc within 24 hours of the start of symptoms was found to cut the risk of still having symptoms at day 7 of a cold by about half. And for prevention, taking zinc for at least 5 months cut cold risk by a third (9). For acute relief zinc gluconate lozenges dissolved in your mouth slowly and containing at least 18 mg of zinc are effective (10).
Dougals RM et al. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD000980.
Hemila H. Vitamin C supplementation and common cold symptoms: factors affecting the magnitude of the benefit. Med Hypotheses. 1999 Feb;52(2):171-8.
Josling P. Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. Adv Ther. 2001 Jul-Aug;18(4):189-93.
Zakay-Rones Z, Varsano N, Zlotnik M, et al. Inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (Sambucus nigra L.) during an outbreak of influenza B Panama. J Altern Complement Med 1995;1:361-369.
Zakay-Rones Z, Thom E, Wollan T, Wadstein J. Randomized study of the efficacy and safety of oral elderberry extract in the treatment of influenza A and B virus infections. J Int Med Res 2004;32:132-140.
Shah SA et al. Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis. Lancet Infect Dis 7.7 (2007b): 473–80.
Gillespie EL, Coleman CI. The effect of Echinacea on upper respiratory infection symptom severity and quality of life. Conn Med 70.2 (2006): 93–7.
Braun, Lesley. Herbs and Natural Supplements: An Evidence-Based Guide, 3rd Edition. Churchill Livingstone Australia, 032010. p. 3951.
Singh M, Das RR. Zinc for the common cold. Cochrane Database of Systematic Reviews 2011, Issue 2. Art. No.: CD001364. DOI: 10.1002/14651858.CD001364.pub3.3.
Eby GA 3rd. Zinc lozenges as cure for the common cold--a review and hypothesis. Med Hypotheses. 2010 Mar;74(3):482-92.