Note: Immune-enhancing herbs may interact or interfere with other medications, or negatively affect chronic health conditions. Always consult a medical professional before combining medicinal herbs with pharmaceutical medications, or if you have ongoing medical conditions or are nursing or pregnant.
Research shows that American ginseng root — revered for centuries as a health and vitality tonic — helps prevent upper respiratory infections when taken for several months. In Traditional Chinese Medicine, tonic herbs such as ginseng are taken to strengthen immunity, but are discontinued during an acute illness (such as a cold). Because products vary in potency, follow manufacturers’ dosage recommendations.
Sometimes referred to as “Indian echinacea,” andrographis reduces the duration and severity of cold symptoms, and it also might help prevent upper respiratory infections, studies show. Compounds in andrographis appear to stimulate immune function and halt viral growth. Look for products standardized to five percent andrographolide (the active constituent), and follow dosage instructions.
Research shows that astragalus can improve immune function in several ways, prodding immune cells into increased activity. Components of astragalus, such as polysaccharides (large, complex sugar molecules that enhance immune activity), along with saponins and flavonoids, have been found to shield cells against the free radical damage that leads to degenerative diseases, such as cancer. In China, researchers have conducted dozens of studies on astragalus with promising results. In one clinical trial, 115 patients with low white blood cell counts took either 10 grams or 30 grams of a concentrated astragalus extract daily. Both groups experienced a significant increase in white blood cell counts after eight weeks of treatment. In Traditional Chinese Medicine, astragalus often is made into a tea, or slices of the root are simmered in soup. In Western herbalism, astragalus is generally taken as an extract or in capsules. Because preparations vary in potency, follow package directions for best results.
Dark blue-black elderberries are rich in compounds that disarm viruses and prevent them from taking over healthy cells. Studies show elderberry offers significant protection against respiratory viral infections. For prevention, take 1/2 teaspoon of liquid extract or 1 teaspoon of elderberry syrup twice daily. To hasten recovery from a cold or flu, take 1 teaspoon of extract or 2 teaspoons of syrup four times a day. Do not consume unripe or uncooked elderberries, which may be poisonous.
Despite a few studies that question its efficacy, numerous studies support echinacea as an effective aid for preventing and treating colds, flu and other infections. Echinacea stimulates infection-fighting immune cells and may increase the production of other immune compounds, such as interferon. Echinacea works best when taken frequently at the first sign of infection: 30 to 60 drops of liquid extract or one to two capsules (300 to 400 mg each) every two hours for the first 24 to 48 hours, followed by the same dosage three times daily for three days after symptoms disappear. Use caution with echinacea if you are allergic to ragweed, mums, marigolds or daisies.
Well-known as an adaptogenic herb (it helps the body more easily adapt to stressors), eleuthero root improves immune function in clinical studies. For best results, take eleuthero for at least three months to strengthen immune response; take it daily for six to eight weeks, then take a one- to two-week break before resuming. Because products vary in potency, follow manufacturers’ dosage recommendations.
In one study concerning the use of garlic for preventing and treating colds, researchers randomly assigned 146 volunteers to two groups. Over a 12-week period, one group received a garlic supplement containing allicin. The other group was given a placebo. At the end of the study, researchers found that the group given the garlic supplement reported that only 24 participants had colds, in contrast to the placebo group, in which 65 participants suffered from colds. The participants taking garlic who did get sick recovered more quickly. If you’re taking prescription anticoagulant drugs, consult your doctor before taking large amounts of garlic because of the herb’s blood-thinning properties. Discontinue garlic supplements seven to 10 days before surgery, and tell doctors you are taking garlic before any unplanned medical procedure. According to the Herb Research Foundation, a typical dosage of garlic is 600 to 900 mg a day of powdered garlic in capsules or tablets (standardized for allicin content); 4 ml a day of aged garlic liquid extract; 10 mg a day of garlic oil capsules; or one medium-sized clove of fresh garlic.
Cultivating the habit of drinking green tea regularly can help strengthen immunity. Green tea contains potent antioxidant compounds that neutralize free radicals and prevent damage to the immune system. In addition, green tea stimulates the liver to secrete interferon, an immune compound that helps fight infection. To bolster immune function, drink three or more cups of green tea daily.
Mushrooms contain a variety of active compounds, including polysaccharides, glycoproteins, ergosterols, triterpenes and antibiotics. Mushroom polysaccharides improve immune function by increasing the activity of macrophages, which have a voracious appetite for harmful microorganisms and cancerous cells. Polysaccharides also trigger the production of a type of white blood cell that kills a wide range of infectious microorganisms and tumor cells. Last but not least, mushroom polysaccharides activate other essential immune factors, including T-cells, B-cells, interferons and interleukins. While all medicinal mushrooms benefit the immune system, each variety contains different compounds that work in various ways to enhance immunity. Therefore, the best approach is to use an assortment of mushrooms to provide a broad base of immune support. Shiitake and maitake mushrooms, fresh or dried, make a delicious addition to soups or stir-fries. Along with a wide variety of other medicinal mushrooms, shiitake, maitake and reishi are available as concentrated extracts and in combinations specifically formulated to enhance immune health. Product potency varies widely, so follow manufacturers’ recommendations for dosages.
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