Seasonal occurrences of cold and flu are to be expected. Targeting the immune system during this time has the potential to help decrease the frequency, severity, or duration of cold and flu symptoms. Decreasing the risk of developing a cold or flu is possible through prophylactic supplementation, especially among high-risk populations, such as in children, the elderly, or those with compromised immune systems. In the event a cold or flu does occur, the desired focus of supplementation may shift to decreasing the duration and severity of symptoms. Zinc may be considered in this case; when given during the initial 24 hours of symptom onset, it has been shown to reduce the number of patients with symptoms after one week.1 Vitamin C is another popular remedy to decrease the length of a cold and has the potential to decrease duration by approximately half a day.2 The ingredients presented in the protocol below reflect research findings that demonstrate efficacy when used prophylactically and therapeutically to support physiological immune function in regards to cold and flu.

Vitamin C Adults: 1 g daily as an ongoing maintenance dose3,4, or 3 to 4 g daily at the onset of symptoms and for the duration of illness2,4 Children: 1 to 2 g daily as an ongoing maintenance dose4,2

  • Reduces the duration of the common cold by approximately a half-day2, or by 8% in adults and by 14-18% in children4

  • Reduces time of confinement by approximately six hours and fever duration by approximately a half-day, relieves chest pain and chills by approximately eight hours when given an extra therapeutic dose at the time of onset of cold2

  • Improves antimicrobial and natural killer (NK) cell activities, lymphocyte levels, chemotaxis, delayed T cell responses, sympathetic nervous response, and induces anti-reactive oxygen species activity2

  • Decreased duration of cold by 59% and increased weekly activity levels by 39.5% when compared to placebo in otherwise healthy adult males3

American ginseng (Panax quinquefolius)

400 mg, once per day, minimum 8-16 weeks in healthy adults as a preventative measure5,6,7

  • Reduces the duration of colds or acute respiratory infections by approximately 5-6 days5,7

  • Reduces the incidence of colds by 25%4, the incidence of influenza and respiratory syncytial virus, and the relative risk of respiratory symptoms by 48%6,8,7

  • Reduces total symptom severity score for sore throat, runny nose, sneezing, nasal congestion, malaise, fever, headache, hoarseness, earaches, and cough6


75-100 mg of elemental zinc as zinc acetate or zinc gluconate lozenges, once per day, within 24 hours of the onset of common cold symptoms, minimum 1 to 2 weeks cold15,16,17,18,19

  • Reduces cold duration by 33%15, or by approximately 1.65 to 3 days in healthy adults cold16,17,18,20,21

  • Zinc acetate equivalently reduces the duration by 40% and zinc gluconate reduces the duration by 28%15, while other sources indicate greater efficacy with zinc acetate in healthy adults20

  • Reduces the incidence of cold symptoms after 5-7 days in healthy adults and children19,21

  • Reduces the duration of muscle soreness by 54%, cough by 46%, voice hoarseness by 43%, nasal congestion by 37%, nasal discharge by 34%, scratchy throat by 33%, sneezing by 22%, and sore throat by 18% in healthy adults19,21

  • Reduces the incidence of common cold development, absence from school, and antibiotic use in children1,17

  • Improves anti-inflammatory and antioxidant profile via reductions in plasma interleukin-1 receptor antagonist (IL-1ra), intercellular adhesion molecule-1 (ICAM-1), TNF-ɑ, MDA, HAE, and 8-oHdG, and increases in IL-2 mRNA in mononuclear cells in healthy adults21,22

  • Reduces duration of symptoms particularly when given within the first 24 hours of symptom onset1,23


Probiotics may reduce the incidence of colds with minor effects on prevention, as well as improve influenza vaccination efficacy for A/H1N1, A/H3N2, and B strains, but is dependent on strain and population.24,25,26


Common Cold

  • 5 billion CFU of Lactobacillus acidophilus NCFM (ATCC 700396), twice per day, minimum 6 months27

  • Reduces the incidence of fever by 53%, cough by 41%, and antibiotic use by 68%

  • Reduces the duration of fever, coughing, and rhinorrhea by 32%

  • Reduces days absent from childcare by 32%


  • 10 billion CFU of Bifidobacterium animalis subs. lactis Bi-07 (ATCC PTA-4802) & Lactobacillus acidophilus NCFM (ATCC 700396), twice per day for 6 months27

  • Reduces the incidence of fever by 73%, rhinorrhea by 73%, cough by 62%, and antibiotic use by 84%

  • Reduces the duration of fever, coughing, and rhinorrhea by 48%

  • Reduces days absent from childcare by 28%


Common Cold

  • 1 billion CFU of Lactobacillus paracasei 8700:2 (DSM 13434) & Lactobacillus plantarum HEAL 9 (DSM 15312), once per day for 3 months28

  • Reduces the incidence of developing more than one common cold episode and number of days with a cold

  • Reduces total symptom scores & pharyngeal symptoms of cold

  • Reduces B lymphocyte proliferation


  • 10 billion CFU of Lactobacillus fermentum CECT5716, once per day for 2 weeks before influenza vaccination and two weeks after29

  • Reduces the incidence of influenza 5-months after vaccination compared to vaccine alone

  • Increases natural killer cells, T-helper response, and IgA levels

  • 10 billion CFU of Lactobacillus rhamnosus GG, twice per day for 4 weeks after influenza vaccination30

  • Increases seroprotection for the H3N2 strain during the supplementation period

  • 500 mg of Saccharomyces cerevisiae (EpiCor®), once per day for 12 weeks31,32

  • Reduces the incidence of cold/flu symptoms with or without prior vaccination

  • Reduces the duration of symptoms with prior vaccination


1 A

2 A

3 A

4 B

5 C

6 B

7 B

8 A

9 A

10 A

11 B

12 C

13 A

14 A

15 A

16 A

17 A

18 A

19 B

20 B

21 A

22 A

23 A

24 B

25 B

26 B

27 C

28 B

29 B

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