The coming cold and flu season is only one of hundreds of reasons that immune function should always be at the top of your list of health priorities. The immune system doesn’t just keep sniffles away — it also is the body’s best defense against potentially deadly diseases, such as avian flu, and well-known killers, such as cancer. Your daily habits, including the foods you eat and your exercise and sleep routines, have a significant effect on your immune function. And even if your lifestyle choices are exemplary, environmental toxins, emotional stress and the wear and tear of aging all conspire to weaken immunity.
The most complex system of the body, the immune system includes the thymus gland, spleen, bone marrow and a vast network of lymph nodes that are scattered throughout the body. The immune system also maintains a variety of white blood cells: Natural killer cells eradicate cancer cells and large white blood cells called macrophages gobble up diseased or damaged cells. In addition, specialized immune compounds, such as interferon, stimulate white blood cells to destroy cancerous cells.
Your immune system never rests — 24 hours a day, every day of your life, your immune system is searching for cells that show signs of infection or cancerous changes. To support and protect your immune system, try to follow these lifestyle suggestions:
• Choose immune-boosting foods. A diet of refined, processed, sugary foods is a recipe for lowered immunity. To build strong immune function, eat a diet rich in fresh vegetables and fruits, which provide a wide range of essential antioxidants and nutrients. The immune system also depends on high-quality proteins and healthful fats, especially monounsaturated fats, such as those found in extra virgin olive oil, to repair tissues and create healthy immune cells. Studies show that adding a daily serving of yogurt with live beneficial bacteria, such as Lactobacillus acidophilus, strengthens immune function. It’s also important to reduce your intake of all types of sugars (including concentrated fruit juices) because even one serving of sugar significantly lowers immune defenses for several hours.
• Exercise — but not to excess. Science has proven that regular exercise — at least 30 minutes most days of the week — increases immune function. Moderate exercise increases the numbers of all types of white blood cells and makes natural killer cells become more active and effective. But interest-ingly, excessive exercise regimes, such as running a marathon, can temporarily hinder immune function.
• Reduce stress. Emotional stressors, such as depression and anxiety, stimulate the secretion of adrenal hormones, which suppress the activity of the thymus gland and white blood cells. Luckily, there are several easy ways to reduce stress in your day-to-day life. In addition to its immune-boosting effects, regular exercise is a potent stress reliever. So are meditation, deep relaxation exercises and massage. Researchers have even found that the simple process of journal writing about stressful incidents improves immune function.
• Sleep more for better health. Lack of sleep negatively affects immune function in a few major ways. First, without enough rest, the body slows its production of disease-fighting white blood cells. Lack of sleep also impairs the activity of natural killer cells and macrophages. And finally, during deep, restful sleep, the body releases powerful immune-enhancing compounds, such as interferon. Make every effort to get enough sleep so that your body is rested and can perform these vital functions.
• Treat infections promptly. Lingering infections, such as respiratory or gum infections, tax the immune system and can significantly impair immunity. Treat infections promptly with immune-boosting herbs such as echinacea (Echinacea spp.) and garlic (Allium sativum). Whenever possible, avoid using antibiotics, because they ultimately weaken immune function. Save antibiotics for infections that cannot successfully be treated with herbs.
• Avoid toxins. Toxic chemicals impair immune function and trigger the formation of cell-damaging free radicals. Toxins are everywhere in our environment these days. Avoid as many as you can by choosing organically grown foods, as well as meats and dairy products that are produced without antibiotics or other chemicals. Use natural alternatives to toxic products in your home, garden and workplace. Whenever possible, avoid exposure to radiation, including x-rays unless absolutely necessary, because radiation damage is cumulative.
For centuries, humans have relied on astragalus (Astragalus membranaceus), garlic and medicinal mushrooms to bolster immune function, and current research supports their traditional use. For optimal immunity, use one or more of these herbs regularly. A delicious way to take them is in the form of a tonic soup (see “Immune-Building Herbal Tonic Soup” on Page 52).
A member of the pea family, astragalus root has been used for more than 2,000 years in traditional Chinese medicine as a popular tonic for strengthening vitality and to bolster resistance to disease. Today, researchers are trying to scientifi-cally validate the herb’s long reputation as an immune enhancer.
Astragalus improves immune function in several ways.
Studies show that astragalus improves immune function in several ways. It triggers the creation of immune cells in bone marrow and lymphatic tissue; it prods immune cells — including natural killer cells and macrophages — into increased activity; and it enhances the production of immune compounds, such as immunoglobulin. 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. For example, in a 1997 study, researchers found that giving astragalus to elderly mice (aged 36 and 60 weeks) restored immune function to that of 10-week-old mice. And in a 1995 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.
Astragalus is available in a variety of forms including the dried root, capsules and liquid extracts. In Trad-itional Chinese Medicine, astragalus often is made into a tea, or slices of the root are simmered in soup. Because bolstering immune function is key to preventing any type of illness or health problem, astragalus often is combined with a variety of other herbs prescribed for various specific conditions.
In Western herbalism, astragalus is generally taken as an extract or in capsules. Because preparations vary in potency, follow package directions for best results.
A member of the lily family, garlic has been prized for its healing properties since at least 2600 BC. Anthropologists have found prescriptions for the herb chiseled onto ancient Sumerian clay tablets. Cultures around the world have embraced garlic as a cure for everything from colds to cancer. Prior to the discovery of penicillin, garlic was the treatment of choice for infections, such as pneumonia, bronchitis, tuberculosis and dysentery.
Scientists believe that it is the same sulfur compounds that imbue garlic with its characteristic odor and flavor that are responsible for the herb’s health benefits. Most of the research has focused on the sulfur compound allicin, which has anti- microbial properties. Allicin is created when alliin, a sulfur-containing amino acid in garlic, comes into contact with another garlic compound, the enzyme allinase. This enzymatic reaction takes place when garlic is chopped, crushed or chewed, but it is destroyed during cooking.
A 2001 clinical trial supports the use of garlic for preventing and treating colds. In the study, researchers randomly assigned 146 volunteers to two groups. One group received a garlic supplement containing allicin. The other group was given a placebo. Over a 12-week period between November and February, the volunteers kept a daily diary in which they recorded cold symptoms. 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 researchers also discovered that the study participants taking garlic who did get sick recovered more quickly.
Because raw garlic can cause gastrointestinal upset if taken on an empty stomach, it’s best to consume it with meals. If you’re adding garlic to a cooked dish, such as pasta or soup, add it at the end of cooking to prevent destruction of the antimicrobial compounds.
If you’re taking prescription anticoagulant drugs, consult your doctor before taking large amounts of garlic because of the herb’s blood-thinning properties. For the same reason, discontinue garlic supplements seven to 10 days before surgery, and tell doctors you are taking garlic before any unplanned medical procedure.
A great deal of controversy exists over the best form of garlic and the proper dosage. 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 alliin content), 4 ml a day of aged garlic liquid extract, 10 mg a day of garlic oil capsules, or one medium-size clove of fresh garlic.
Although we tend to think of mushrooms primarily as ingredients for creating gourmet meals, in Traditional Chinese Medicine mushrooms have been highly prized for thousands of years for their potent healing benefits. In Japan and China, medicinal mushrooms, such as shiitake, maitake and reishi, have long been regarded as longevity tonics. Research is proving that these beneficial fungi are powerful allies for strengthening the immune system.
Mushrooms contain a variety of active compounds, including polysaccharides, glycoproteins, ergosterols, triterpenes and antibiotics. Thus far, researchers have most intensively focused on the polysaccharides, the same type of compounds found in astragalus. As with astragalus polysaccharides, 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. You can find shiitake and maitake mushrooms fresh or dried in many grocery stores, and they 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. Because products vary widely in potency, follow manufacturers’ recommendations for dosages.
Laurel Vukovic writes and teaches about herbs from her home in southern Oregon. She is the author of 1001 Natural Remedies (DK, 2003) and Herbal Healing Secrets for Women (Prentice Hall, 2000).
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