<\/span><\/h2>\nLong touted as a cold cure,\u00a0vitamin C\u00a0doesn\u2019t appear to prevent respiratory illnesses. But it may help shorten colds, according to a\u00a0review of studies\u00a0in the\u00a0Cochrane Database of Systematic Reviews<\/em>. When study participants took 1 gram of vitamin C every day (not just when illness struck), colds that did occur were 8% shorter in length in adults and 14% shorter in children, says Harri Hemil\u00e4, MD, PhD, an adjunct professor in the Department of Public Health at the University of Helsinki in Finland.\u00a0<\/p>\nCould vitamin C work against COVID? There\u2019s no evidence yet that it will help. But Hemil\u00e4 says there\u2019s little harm in giving it a try. Be careful to avoid overdoing, it though. Large\u00a0doses of vitamin C above 500 milligrams daily can cause\u00a0digestive upset\u00a0and may increase the risk for\u00a0cataracts\u00a0and\u00a0the risk\u00a0of\u00a0kidney stones\u00a0in some people.<\/p>\n<\/section>\n<\/div>\n
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\n<\/span>Vitamin D<\/span><\/h2>\nAmong vitamins that may help ward off illness,\u00a0vitamin D\u00a0is a sure bet. A Cochrane\u00a0review\u00a0showed that the \u201csunshine vitamin\u201d cut the number of\u00a0colds\u00a0people caught if they took it every day or at least every week. And the incidence of colds was slashed in half among people who started out deficient in the vitamin, according to the study.<\/p>\n
Recent\u00a0research\u00a0shows that people with low levels of vitamin D are more likely to have a severe case of COVID-19. But so far, no one has studied whether a supplement can help, although research is underway. Excess doses — taking more than 60,000 international units a day for several months — can be toxic. This causes calcium to build up in your blood, leading to nausea,\u00a0vomiting, weakness, bone pain, and kidney problems.<\/p>\n<\/section>\n\n<\/span>Vitamin E<\/span><\/h2>\nVitamin E\u00a0shows particular promise for improving immune function in seniors. A large\u00a0study\u00a0of nursing home residents in\u00a0The<\/em>Journal of the American Medical Association\u00a0<\/em>found it could make a big difference in staying healthy this winter. \u201cWe showed that supplementation with 200 IU\/day of vitamin E for a year resulted in significant reduction in respiratory infection –particularly upper respiratory infections, including common colds,\u201d says Simin Nikbin Meydani, DVM, PhD, a senior scientist and director of the Nutritional Immunology Lab at the Human Nutrition Research Center on Aging at Tufts University.<\/p>\n<\/section>\n\n<\/span>Echinacea<\/span><\/h2>\nThis popular\u00a0cold remedy\u00a0has a mixed record. But the variation between studies could be due to the dose, the part of this flower used to make the supplement, and even the time of year it was grown,\u00a0research suggests.<\/p>\n
A\u00a0study\u00a0shows that echinacea is somewhat effective at\u00a0preventing colds\u00a0if taken three times a day during the cold season as a preventive measure and five times a day when you\u2019re actually battling a cold. Using an extract of echinacea in drop form lowered the incidence of colds by 26% and also cut how long the colds lasted. And those taking it used less pain medication when they had colds.<\/p>\n
But a newer\u00a0study\u00a0did not find it prevented the common cold or cut short how long a cold lasted.<\/p>\n<\/section>\n<\/div>\n
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\n<\/span>Zinc<\/span><\/h2>\nThere isn\u2019t good data to show that zinc prevents colds. \u201cHowever, there are half a dozen randomized trials that found that zinc lozenges can shorten the duration of colds when started after the onset of symptoms,\u201d Hemil\u00e4 says.<\/p>\n
Recovering from a cold\u00a0was three times higher and colds were shortened by 30%-40% among people taking high-dose zinc lozenges, according to\u00a0data\u00a0in the\u00a0Journal of the Royal Society of Medicine<\/em>. You need 80-100 milligrams of the supplement daily to get the effect. Zinc gluconate and zinc acetate are equally effective.<\/p>\nOne\u00a0study\u00a0showed that zinc reduced the risk of\u00a0pneumonia\u00a0in older people. People who are older may be deficient in the mineral. Possible\u00a0side effects\u00a0include a bad taste in your mouth, loss of smell if used as a spray,\u00a0indigestion, diarrhea,\u00a0headache, nausea, and vomiting.<\/p>\n<\/section>\n\n<\/span>Probiotics<\/span><\/h2>\nThe evidence is mixed for taking\u00a0probiotics\u00a0to prevent respiratory infections. A review of 33 studies found that while most research found some benefit, it needed further study. One\u00a0study\u00a0found that probiotics might help you cut respiratory infections short, compared to not taking the supplement.<\/p>\n
When choosing a product, lead study author Tracey J. Smith, PhD, recommends looking for the strains\u00a0Lactobacillus rhamnosus<\/em>\u00a0and\u00a0Bifidobacterium animalis lactis<\/em>. These probiotic microorganisms seem to reduce symptoms by muting the body\u2019s inflammatory response, she says. (But if you have a serious chronic disease, check with a doctor first.)<\/p>\n<\/section>\n\n<\/span>Glutathione<\/span><\/h2>\nThe\u00a0antioxidant\u00a0glutathione, which is produced naturally by the body, boosted an important measure of immunity when given to people as a supplement in one\u00a0study. These included increases in lymphocytes — white blood cells that are a major part of the immune system, including a subset of\u00a0lymphocytes\u00a0known as natural killer cells, says study author John P. Richie Jr., PhD, a professor of public health sciences and pharmacology at Penn State University College of Medicine in Hershey, PA. But the study was small — only 12 people — and more studies are needed to show that glutathione actually prevents or reduces illness.<\/p>\n<\/section>\n