Preventive Botanical Medicines During Flu Season

The best treatment for seasonal influenza is prevention. In all the traditional medicine systems of Africa, Asia, the Middle East, and so on, the distinction between plants as foods and as medicines is vague and arbitrary. People intent on protecting themselves and their children from flu who stay up late, snack on sweet or refined treats, and skip balanced, nourishing meals while religiously taking doses of echinacea or other herbs are fighting a losing battle. In a nutshell, proper nutrition is the best method of avoiding coming down with the flu in the first place. A healthy diet, rich in fruits and vegetables as well as spicy, warming dishes prepared with cayenne or jalapeno peppers (Capsicum spp.), mustard (Brassica nigra) seed, ginger (Zin-giber officinale) rhizome, horseradish (Cochlearia armoracia) root, and garlic (Allium sativum) bulbs, are the best preventative. Vitamin-rich herbs, as teas or juices, can also be added to the diet during flu season. These include rose hips (Rosa canina) and berries, as teas or food. Other key nutrients include selenium. Animal studies show that selenium-deficient mice are more susceptible to flu virus and also tended to develop pneumonia when infected with the flu. Interestingly, selenium deficiency altered both the animals’ immune systems and the viral pathogen itself.

The rapid replication of the virus induces oxidative stress in the host cells. Cellular glutathi-one content helps the host down-regulate viral replication, protects against viral production in airway epithelial cells, and has anti-influenza activity in vitro and in vivo. N-acetyl-cysteine (NAC) is a precursor to reduced glutathione and appears to quiet production of pro-inflammtory cytokines in glutathione-depleted alveolar macrophages.

Mice fed a vitamin E-supplemented diet had significantly lower pulmonary viral titers compared to mice on a regular diet and the vitamin appeared to decrease the production of pro-inflammatory cytokines in cells. Other antioxidants are also important: quercitin appeared to protect the lung from free radicals released during influenza virus infection. Curcumin, from turmeric, induced synthesis of glutathione in alveolar epithelial cells, and antioxidants generally suppressed the production of IL- in bronchial epithelial cells. Vitamins (vitamins A, C, B2, B5, folic acid, B12, and Kl) and the mineral magnesium have also been shown to improve immune function in influenza.

Thus, a combination of a diet rich in fruits, vegetables, herbs, and spices (to provide antioxidants, vitamins, and minerals) along with well-chosen supplements are important to avoid getting the flu and to ensure a milder case of the flu if one is contracted.

In addition, research is beginning to show that the prophylactic use of adaptogens helps reduce susceptibility to respiratory infections and influenza. In a study of 43 adults 65 and older, participants took 400mg/day of American ginseng (Panax quinquefolius) extract or placebo for 4 months. In the last two months of the study, the frequency and duration of colds was reduced by nearly 50% and symptom duration by more than 50% in the active group. In another study of 323 adults (ages 16-65), American ginseng again reduced the mean number of colds and severity of symptoms. In two randomized trials of elderly individuals living in a long-term-care setting, patients given 400mg/day of American ginseng suffered less laboratory-confirmed influenza than did the placebo groups even though the trials were relatively short (8 and 12 weeks). A related species of ginseng has also shown benefit: In a randomized, placebo-controlled, double-blind trial, 227 volunteers were treated with an influenza vaccine and placebo or 100 mg of an Asian red ginseng (Panax ginseng) extract for 3 months. Colds and flu were highly reduced in the active group (15 vs. 42 cases). Although clinical research on other adaptogens in influenza prevention are not available, it is likely they will have the same ability to strengthen the individual and increase resistance to infection, with California spikenard (Aralia racemosa, Aralia californica) having perhaps the greatest affinity for the lungs and patients with influenza among all the traditional adaptogens.

Traditionally, tonic-digestive “alternatives” to help maintain optimum digestive function are considered useful preventatives as well. In most traditions, herbs are used to maintain good bowel function as a method of preventing infectious diseases. Although no known studies exist on sluggish transit time and chronic constipation related to infectious disease incidence, the theoretical association is plausible. There may be an indirect relationship between the volume of resorbed bowel metabolites and the freedom of the body’s immune system to respond to external infectious agents. Many herbal systems gave cathartic herbs or enemas to enhance resistance to infection. Our preference is to avoid such drastic measures, and we instead use mild alternatives such as dandelion root (Taraxacum officinale) that are more gentle liver stimulants along with adequate fluid and fiber intake for those prone to constipation.