Zinc for Colds
Zinc lozenges have become a popular treatment for the common cold. Forms of zinc available on the market include zinc acetate, zinc citrate, zinc gluconate, zinc picolinate, and zinc sulfate.
Taking zinc, either as a syrup or lozenge, through the first few days of a cold may shorten the misery of an upper respiratory infection, the latest research shows. The research -- a review of 15 past studies on the subject -- also found that zinc appeared to prevent colds in people who used it over the course of about five months.
Other studies show no benefit, which may be partly due to the different formulations of zinc.
Some experts suggest that zinc should not be taken for long periods of time. If it is, it may induce a copper deficiency in the body.
Can zinc also help prevent colds or the flu? So far, there isn't good evidence to support zinc lozenges for cold or flu prevention.
Elderberry for the Flu
There's some promising evidence that elderberry might help treat the flu, Leopold says. Elderberry appears to boost the production of some immune cells and may also help block a virus's ability to spread. One study shows that taking 4 tablespoons a day for three days of a specific formulation of elderberry extract -- Sambucol -- appears to shorten the symptoms of flu by 56%. It also seems to reduce some flu symptoms, like fever. However, the study was small and the full implications aren't clear.
Garlic for Colds and Immunity
Like a number of other supplements, garlic seems to stimulate the immune system. Garlic may also help fight viruses. Also, there is some preliminary evidence that garlic may lower the risk of catching a cold. Garlic works best when consumed raw, either crushed, diced, or minced. Overcooking garlic may destroy important medicinal compounds and the enzymes necessary for it to be effective.
However, more research needs to be done. Note: Garlic may be dangerous in people taking blood thinners.
Ginseng for Cold and Flu
Although commonly used as a mild stimulant, the different ginseng species may also boost the immune system and help prevent or treat cold and flu. One species, panax ginseng, may also increase the protection offered by the flu vaccine.
Coates singles out a specific blend of North American ginseng sold as Cold fX. Preliminary results suggest that Cold fX, when taken for several months during flu season, seems to lower the risk of contracting either cold or flu. One study looked at Cold fx as a treatment, and found that it reduced the duration and severity of symptoms. "The jury's still out, but the evidence is promising," says Coates.