Nutritional Support for Colds and Flu


By Jim English

Humans lived for millions of years without the benefit of modern pharmaceutical antibiotics. Pharmaceutical antibiotics were first introduced into medicine in the 1930’s. Prior to that time, physicians and their patients relied primarily on antimicrobial substances like colloidal silver, antiseptics like alcohol and hydrogen peroxide, and various plant extracts which stimulated the body’s own defense mechanisms. This latter approach – that of stimulating the body’s defenses – is rarely considered today in ‘orthodox’ medicine. Although there are few immune-stimulating pharmaceutical drugs available today, there are a number of immune-enhancing nutrients and herbs that can dramatically energize a flagging immune system, and help overcome an attack by bacteria and viruses.

Immuno-Supportive Herbs

Herbs have been used for centuries in virtually every culture in the world. Native American medicine relied heavily on the use of herbs, and traditional herbal remedies are still commonly prescribed in Eastern countries such as China, Korea, and Japan as well as Europe. Over time, trial and error led to the development of folk medicines, with the most effective remedies being passed down through the generations. Herbs have been used in an attempt to treat nearly every known affliction and disease, with mixed results. While some herbs have been shown to be ineffective, others have stood the tests of time and research, proving their worth. The following examples point out how nature has provided us with safe, effective methods of improving our health and quality of life.


In traditional Chinese herbal medicine Astragalus is believed to promote and enhance the immune system, replenish the ‘defensive energy’ and accelerate wound healing. A. membranaceus, the form of Astragalus used for medicinal purposes, is believed to enhance immune function by altering the metabolism of immune cells. Studies in both humans and laboratory animals have demonstrated a potent antiviral potential via its ability to protect against infection from the viruses that cause influenza and the common cold. Both oral and nasal administration of Astragalus extracts have offered protection against the common cold. In patients who are susceptible to colds and flu, treatment with Astragalus for short periods of time (two weeks) enhanced interferon induction by the white blood cells, resulting in increased levels of cytokines (such as interleukin-2 and IgA and IgG).

Astragalus treatment leads to an increase in T-helper cell activity. This increase in immune function was clearly demonstrated in one study where immuno-deficient and healthy normal mice were treated with Astragalus extract. This effect has been noted in humans as well. When mononuclear cells from cancer patients and healthy volunteers were inoculated with extracts of Astragalus, not only did T-cell levels rise to levels similar to that of healthy cells (prior to treatment), T-cell levels in cells from healthy individuals were also significantly increased.


Echinacea, an herb native to North America, has played an important role in Native American medicine. It was used by numerous tribes to treat a variety of symptoms and diseases, including: sore mouth and gums, toothache and coughs, and as an anti-inflammatory and antiseptic agent.

More recently Echinacea has been closely examined for its influence on immune cell proliferation, antibody production, and antiviral activities. One of the most popular uses of Echinacea is for support and recovery from the common cold and influenza. Two recent studies support the use of Echinacea for this purpose.

In the first study, 108 patients with colds received either Echinacea or a placebo for eight weeks. Of those patients receiving the Echinacea, 35.2 percent recovered and remained healthy, while only 25.9 percent of the placebo group remained healthy. When patients did become infected, the length of time between infections was 40 days for the Echinacea group vs. only 25 days for placebo. When infection did occur in patients receiving Echinacea, the symptoms were less severe and resolved quicker.

In a second study, 180 patients with influenza were given either an E. purpurea Echinaceaextract or a placebo. The group receiving Echinacea showed significant reduction of cold symptoms.

Cat’s Claw 

Cat’s Claw (Unicaria tomentosa), a woody vine that grows in Peru, is a traditional phytomedicine of the Ashaninka Indians. The Ashaninkas drink a tea made of the bark once every week or two for general health. In the event of an illness, they consume about a liter every day until all symptoms have disappeared.

Both the root and the bark of Cat’s Claw, a liana growing to 100 feet or more, are sources of a rich variety of pharmacologically active compounds. Among some of the compounds found in U. tomentosa are catechins, alkaloids, ellagic acid and other phenolic antioxidants which are beneficial in the treatment of specific types of cancer. The most immunologically active alkaloids, the oxindole alkaloids, isopteropodine and pteropodine, have been found by Dr. Klaus Keplinger, an Austrian researcher, to stimulate immune function. In addition, the presence of glycosides, proanthocyanidins and beta sitosterol help provide anti-viral, anti-tumor and anti-inflammatory support for the body.


Ginseng has been used for centuries in China, Japan, Korea, and parts of the former Soviet Union for its supportive role in maintaining health. As an adaptogen, Ginseng is believed to produce a state of increased resistance to stress, supporting our ability to resist disease by building up our general vitality and strengthening our normal body functions.

Soviet researchers have been particularly keen on ginseng and have claimed their studies show the herb and its extracts can boost immunity, inhibit cancer, increase energy and physical stamina and have variable effects on blood pressure and blood sugar.

A recent study found that ginseng helps prevent symptoms of the common cold and improves antibody response to influenza vaccine. For 12 weeks, 227 volunteers who visited three private medical practices in Milan received daily oral capsule doses of either 100 mg of a standard Ginseng extract or a placebo. During the fourth week they received an influenza vaccination. There were only 15 cases of influenza or common cold in the group receiving the ginseng extract, versus 42 cases in the group receiving the placebo. By the eighth week, antibody titers rose to an average 272 units in the ginseng group, versus only 171 units in the placebo group. Additionally, at both the eighth and twelfth weeks, natural killer cell activity was nearly twice as high in the Ginseng group versus the placebo group.

Antioxidants Support Immune Response 

Recent studies have shown how antioxidants may play an important role in the treatment of viral diseases. Antioxidants not only reduce disease symptoms, but may also reduce the long-term effects of chronic oxidative stress, which has been linked to the development of cancer from some viral infections. Oxidative stress is seen in individuals infected with influenza, immunodeficiency virus and hepatitis.

Vitamin C

Vitamin C has seemingly been at the center of nutritional research, particularly with regard to the common cold. It is well known that vitamin C is a powerful antioxidant, and this protective activity is now proving vital in recovery from infection. A number of studies have found that, during infection, there is a marked decrease in vitamin C levels in plasma and white blood cells. The concentration of vitamin C in phagocytes and lymphocytes is over 10 times greater than in plasma, and low intake of vitamin C has been shown to decrease phagocytic activity in animal models.

Other studies have shown that higher vitamin C concentration increases the proliferative responses of T-lymphocytes in vitro. Vitamin C has also been reported to induce the production of interferon in cell culture, and one study has found a correlation between natural killer cell activity and vitamin C concentration in leukocytes. Under in vitro conditions, vitamin C has been found to inactivate viruses and bacteria. In human studies doses higher than 100 grams per day have been used for severe bacterial and viral infections.

In a recent study, Italian researchers found that two grams per day of ascorbic acid (vitamin C) was effective in restoring bronchial responsiveness in hospital workers suffering from upper respiratory infections. The authors suggest that ascorbic acid can effectively re-establish the redux state in inflamed airways and may prove beneficial for treatment of coughs during upper respiratory infection.

Vitamin E 

Vitamin E, the body’s premier fat-soluble antioxidant and complement of vitamin C, is the major protective antioxidant for cell membranes. Just as vitamin E protects serum lipoproteins and regulates prostaglandin balance, new research suggests that vitamin E supplementation may enhance phagocytosis, cell-mediated immunity, humoral immunity, and reduce the effects of stress on the immune response.

In an animal study on heart disease in the elderly, aged mice were fed vitamin E at 500 parts per million two months before exposure to influenza. These animals were found to have substantially lower amounts of the influenza virus in their lungs than control mice given smaller amounts at 30 parts per million.

A related study on age and immune response involved 47 subjects, aged 61 to 79 years. Researchers reported that those receiving a supplement containing vitamin E and other micronutrients showed a significant increase in immune response. Specifically, an increase in CD57 natural killer cells, T-cells and T-cell subsets. Conversely, in the placebo group there was a decrease in T-cells, CD4 cells and the CD4:CD8 ratio. Researchers concluded that nutritional intervention provided an effective approach for delaying the overall decline in immune function noted with increasing age.


Glutathione is an intracellular thiol (sulfur-containing compound) that acts as the body’s principal antioxidant by providing intracellular defense against oxidative stresses caused by free radicals, reactive oxygen intermediates, and certain toxic chemicals. Glutathione aids in the recycling and maintenance of tissue vitamin C and vitamin E levels. Glutathione also works by detoxifying hydrogen peroxide (H2O2) and other organoperoxidases (free radicals), and by protecting against oxidation within cells via the Glutathione Redux Cycle. This role as a free radical scavenger is primarily accomplished through glutathione peroxidase (GSH px), which interacts to reduce hydrogen peroxide to harmless water and thereby limit its capacity to cause damage.

Whey Protein Concentrate (WPC) is a nutritional supplement that increases intracellular production of glutathione (GSH), to enhance the immune system. It has been theorized that the ability of lymphocytes (CD4 cells) to correct oxidative damage is determined by their capacity to regenerate intracellular stores of glutathione, which allows them to respond vigorously to a wide variety of antigens.

In 1981, researchers discovered that mice fed a non-denatured whey protein concentrate exhibited a marked increase in antibody production in response to T-cell dependent antigens. Numerous experiments in subsequent years have confirmed this early observation. Thus, enhanced immunity against colds and hepatitis, and most dramatically, pneumococcal infection, could be accomplished through dietary supplementation with whey protein concentrates (WPCs).

Vitamin A

Vitamin A is one of the best documented nutrients for supporting immune function. A deficiency in vitamin A is known to reduce resistance to infection by lowering neutrophil phagocytosis, cell-mediated immunity, humoral response and interleukin II production. Recent research has found a strong link between vitamin A intake and upper respiratory infections.

One 1996 study of newborn infants recorded substantial decreases in upper respiratory infection in newborns given 50,000 IU of vitamin A versus a placebo. Researchers concluded that neonatal vitamin A supplementation reduces infant mortality rates, as well as lessens the severity of respiratory infection.

A second study linking vitamin A intake and respiratory infection followed 28,000 children between six months and six years of age. Higher intake of vitamin A was strongly associated with fewer upper respiratory infections, lessened incidence of diarrhea and a reduction in cough and fever. Of notice, there was a significant positive association with vitamin A intake and the lowered incidence of cough alone, a sign of a healthy respiratory epithelium.


N-Acetyl Cysteine (NAC) has been extensively researched for its antioxidant properties, particularly in its potential to neutralize the chemical by-products of smoking. NAC has been used for bronchial congestion for over thirty years, and is used to fight chronic lung diseases because of its ability to break up mucus. However, one of the most exciting areas of NAC research is in the area of immunology. NAC has been found to significantly enhance human T-cell function, especially in older individuals. NAC is currently undergoing clinical trials around the world as an augmenter of immune function in people with AIDS. Its ease of conversion to both extracellular and intracellular glutathione, coupled with its stability and long half-life in the body, makes it an economical and powerful antioxidant.

Thymic Protein A 

Another powerful immune enhancer is Thymic Protein A, a protein extracted from calf thymus which increases T-cells. T-cells are types of white blood cells produced by the thymus gland which locate and destroy foreign invaders. The thymus gland, which is located behind the sternum (breast bone), shrinks as we age, resulting in a decline in immune function. Thymic Protein A has shown in numerous animal studies to dramatically improve immune function. Thymic Protein A is safe and can even be used by children.

Olive Leaf Extract 

Olive leaf extract is a potent anti-viral, anti-bacterial and anti-fungal supplement that has been shown to be effective at boosting the immune response and aiding the body in defending against infections. Two components of olive leaf extract, oleuropein and calcium elenolate, have been shown to be particularly effective at inactivating the viruses that cause colds and flu.

In the late 1960s researchers from the Upjohn Company discovered that the components of olive leaf extract exhibited powerful antibacterial and antiviral effects. Of special interest was an antimicrobial fraction, calcium elenolate, that proved to be lethal to every virus the researchers tested it against. Further research demonstrated that other components of olive leaf extract are toxic to a wide range of bacteria, protozoa, yeasts, parasites and fungi. Most impressively, olive leaf extract was found to effectively inhibit Staphylococcus aureus, a bacteria notorious for its ability to mutate against antibiotics and responsible for many hospital-acquired infections.

Olive leaf extract is a proven antimicrobial substance that is safe for preventive and daily consumption. Olive leaf extract’s safety and efficacy has been demonstrated by hundreds of clinicians around the country who have used olive leaf extract to treat their patients with remarkable results.


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