In addition to getting enough rest, exercising regularly, and eating plenty of antioxidant-rich foods—the building blocks of healthy immunity—you may want to consider taking an herbal supplement to counteract the natural decline in your immune system as you get older. However, it’s important to remember that a pill can’t make up for an unhealthy lifestyle, and just because these herbs are natural doesn’t mean they’re automatically safe for you to take. Read labels carefully and obey warnings, and let your doctor know you’d like to try them, since some herbs can interact with drugs or other natural remedies.
The antioxidant and anti-inflammatory herb North American ginseng (Panax quinquefolius) contains compounds called ginsenosides and polysaccharides that seem to be responsible for the herb’s immune-boosting effects. It broadly supports the immune system and protects against stress, and you can take it indefinitely to help shore up your immune system as it naturally slows down with age. A 2009 review of studies in Evidence-Based Complementary and Alternative Medicine concluded that while North American ginseng doesn’t reliably reduce the incidence or severity of colds and respiratory infections, it appears to shorten their duration. The herb might also exert antitumor effects: A ginseng extract slowed the spread of and killed human colon cancer cells in lab tests, according to a 2010 study in Phytomedicine.
Preparations and quality of this herb vary widely, so look for standardized products that indicate the ginsenoside content and follow the package dosing directions. Take it regularly throughout the cold and flu season, or at the first sign of a cold to shorten its duration. If you use it long-term, take two to three weeks off every four months. People with fibroids or with a history of breast cancer shouldn’t take it, and it can interact with some drugs for heart disease, diabetes, and depression.
Astragalus membranaceous is another nontoxic herb you can take indefinitely to improve disease resistance and help fight off chronic or recurrent infections. Despite its long history of use in China, it hasn’t been studied often in humans. Astragalus reduced production of several inflammatory markers in mouse cells, according to a 2008 study in the Journal of Medicinal Food. In other lab and animal studies, astragalus increased T cell counts in samples with low levels (common in older adults), enhanced antibody responses, and improved white blood cells’ ability to eliminate harmful intruders. Additionally, astragalus restored the white blood cell response of older mice to levels normally found in younger mice and partially reestablished immune function in mice with tumors or other immune problems, noted a 2007 study in the Journal of Ethnopharmacology. In one of the few human studies, patients with depressed immune systems due to stomach trauma were given astragalus, which helped restore cellular immunity. And in a pair of studies investigating astragalus, echinacea, and licorice, researchers found that each of the supplements boosted immune cell activity for up to seven days (the combination was even more powerful).
Look for standardized extracts of astragalus in liquid, capsule, or tablet form. Follow the daily dosing directions on the package. People who are on immune-suppressing drugs to treat cancer or who are organ-transplant recipients should not use astragalus.
Also called purple coneflower, echinacea (E. purpurea and E. angustifolia) is one of the most-studied herbs for cold prevention. Lab and animal studies indicate it has antiviral and anti-inflammatory properties and activates white blood cells. And while studies in humans show echinacea doesn’t prevent colds, it does seem to shorten their duration. A 2007 study in the International Journal of Sports Medicine noted that volunteers who took echinacea for four weeks had higher levels of antibodies, and in those who caught respiratory infections, symptoms lasted less than half as long as in those taking a placebo (about 3.4 days, compared to 8.6 days).
Buy products that contain both purpurea and angustifolia species standardized to 4 percent echinacosides. Take echinacea at the first sign of a cold, but don’t use it continuously for more than ten days. Take one dropperful of tincture in water four times a day, or two capsules of freeze-dried extract four times a day, or follow the package directions. Don’t use echinacea if you have an autoimmune condition such as lupus or rheumatoid arthritis.