Vitamin C Supplements
You need vitamin C for a healthy immune system, however you should get it from the fruits and vegetables you eat so that you also get other important nutrients, fiber and other antioxidants that you won't get from dietary supplements. There is no current scientific evidence to support the idea that taking large doses of vitamin C will prevent or reduce the symptoms of colds or flu, however you can take dietary supplements to assure that you get enough vitamin C on the days you don't eat enough fruits and vegetables.Zinc Supplements
Zinc is a mineral that is needed for a healthy immune system and is often sold as an over-the-counter natural treatment for the common cold. One meta-analysis that compared several studies on zinc found that taking zinc within 24 hours after the start of a cold may help to reduce symptoms, however other studies show little or no benefit. Zinc sold in a nasal gel form has been shown by several studies to cause a loss of the sense of smell in some patients and should be used with caution. Zinc is often sold as ingreident in lozenges that may help to sooth a sore throat.Echinacea
This herb is available as a dietary supplement and is used to prevent or decrease the duration of the common cold. Some studies show mixed results, however a meta-analysis of several studies reports that taking echinacea supplements may actually be effective. The flowers parts of the echinacea purpura plant appears to offer the most beneficial form.Probiotics
These "friendly bacteria" help to keep your digestive tract healthy and appear to have some beneficial effect on your immune system. Probiotics may be found in dietary supplements or as a nutritional ingredient in yogurt and other foods. Research supports the use of probiotics for reducing the symptoms and duration of the common cold. Your best bet for keeping healthy and reducing your risk for catching the cold or flu is to eat a healthy diet with lots of fruits and vegetables and get plenty of exercise and enough sleep each night. You can also reduce your risk of influenza by getting a flu shot at the beginning of the flu season.Sources:
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Caruso TJ, Prober CG, Gwaltney JM Jr. "Treatment of naturally acquired common colds with zinc: a structured review." Clin Infect Dis. 2007 Sep 1;45(5):569-74. Epub 2007 Jul 20.
Alexander TH, Davidson TM. "Intranasal zinc and anosmia: the zinc-induced anosmia syndrome." Laryngoscope. 2006 Feb;116(2):217-20.
Shah SA, Sander S, White CM, Rinaldi M, Coleman CI. "Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis." Lancet Infect Dis. 2007 Jul;7(7):473-80.
Linde K, Barrett B, Wölkart K, Bauer R, Melchart D. "Echinacea for preventing and treating the common cold." Cochrane Database Syst Rev. 2006 Jan 25;(1):CD000530.
Schoop R, Klein P, Suter A, Johnston SL. "Echinacea in the prevention of induced rhinovirus colds: a meta-analysis." Clin Ther. 2006 Feb;28(2):174-83.
de Vrese M, Winkler P, Rautenberg P, Harder T, Noah C, Laue C, Ott S, Hampe J, Schreiber S, Heller K, Schrezenmeir J. "Probiotic bacteria reduced duration and severity but not the incidence of common cold episodes in a double blind, randomized, controlled trial." Vaccine. 2006 Nov 10;24(44-46):6670-4.
Winkler P, de Vrese M, Laue Ch, Schrezenmeir J. "Effect of a dietary supplement containing probiotic bacteria plus vitamins and minerals on common cold infections and cellular immune parameters." Int J Clin Pharmacol Ther. 2005 Jul;43(7):318-26.
