By Michael Castleman
And with a few simple changes to your diet and daily routine, you can too.
It’s possible for a healthy person to takenatural steps that significantly improve her immune response, says Anne Simons, M.D., an assistant clinical professor at theUniversity of California, San Francisco and the author of Before You Call the Doctor (Ballantine Books).
You can even increase the effectiveness of the flu vaccine, she adds.
Immune-boosting herbs, the right vitamins, even exercise helps.
So as colds and flu ramp up and people start getting sick all around you, try these tips to increase the chance that you won’t be joining them.
1. Eat your antioxidants.
“A diet high in fruits and vegetables, whole grains, nuts and seeds provides optimal immunity,” says Andrew Weil, M.D., founder and director of the Integrative Medicine Program at the University of Arizona.
And, according to a 2007 Swiss study published in the Annals of Nutrition and Metabolism, an adequate intake of vitamin A (the recommended daily requirement for women is 700 micrograms, found in one sweet potato) will boost immune function and reduce infection risk.
2. Take a multivitamin.
Even with a diet rich in antioxidants, it can be difficult to get the full range of vitamins and minerals your body needs. A vitamin-mineral supplement may be necessary to enhance immune function.
But don’t assume more is always better, says nutritionist Elizabeth Somer, R.D., author of The Essential Guide to Vitamins and Minerals (Collins Reference). “While moderate doses of some nutrients stimulate the body’s defense system, larger doses impair immune function.”
Zinc supplements, she points out, have been shown to shorten the duration of colds in several studies. But an overdose – more than about 150 mg daily – can actually reduce the body’s defenses.How do you know when you’ve taken too much? Nausea, vomiting, diarrhea and headaches are all side effects of too much zinc, according to the National Institutes of Health.
3. Take immune-boosting herbs.
Research on medicinal herbs that enhance immune function is “extensive and compelling,” says Mark Blumenthal, executive director of the Austin, Texas-based American Botanical Council, a nonprofit research organization
To get the most herbal immune support against colds and flu, he recommends the following:
Astragalus. This Chinese herb stimulates T-helper and natural killer cells, which are essential elements of the immune system. Chinese clinical trials have shown that the herb stimulates production of interferon, the body’s own antiviral agent.
In fact, astralagus supplements can give an immune-cell boost that lasts for at least 7 days, according to a 2007 study by the National College of Naturopathic Medicine in Portland, Ore.
Echinacea. The root of this daisy-like flower native to the Midwest is the nation’s most popular – and controversial – immune stimulant.
Some studies have shown that it significantly reduces susceptibility to colds and flu, as well as their severity and duration. Others show no benefit at all.That said, the data is promising. A Swiss analysis of the best studies, published inClinical Therapeutics, shows that echinacea reduces the risk of catching a cold by 55%. And a 2007 analysis of 14 rigorous reports by University of Connecticut researchers showed that the herb reduces cold susceptibility 58%, and the duration of colds by 1.4 days.
Elderberry. This delicious berry is rich in anthocyanins, a healthful chemical found in purple and red fruit. Also known assambucus, elderberry is an age-old treatment for many illnesses, including the flu.
In a study published in the Journal of International Medical Research, researchers gave 60 flu sufferers a placebo or elderberry syrup four times a day. The elderberry group recovered an average of four days faster.
Meanwhile, a 2010 Columbia University research review said the berry is a “promising” treatment for viral influenza infections but called for more rigorous studies.
Ginseng. In Chinese medicine, ginseng is considered a tonic, an herb that promotes overall health. The reason? It’s a powerful immune stimulant.
How effective is it? In a study at Eastern Virginia Medical School, researchers gave ginseng or a placebo to 198 elderly nursing home residents. After 12 weeks, the ginseng group caught just one-tenth the number of colds.
And a 2009 review of five separate studies by Canada’s University of Alberta found that North American ginseng will shorten the duration of colds when taken as a preventative measure for 8-16 weeks.
Garlic. As an herbal medicine, garlic is best known for helping lower cholesterol and reduce the risk of heart disease. But that folk wisdom about chewing on garlic when you feel a cold coming on could have merit. Its active ingredient, allicin, seems to block enzymes that play a part in viral infections.
And supplements seem to work as well as the real thing.
A 2009 research review by the University of Western Australia looked at studies on garlic and colds. In one, volunteers who took garlic supplements had fewer than half the number of colds – and fewer sick days – than those who took a placebo.
4. Get enough sleep.
Ever pull an all-nighter and then get sick? Sleep less than you should and your immune system is likely to suffer.
There’s no “normal” amount of sleep, but the healthy minimum is seven hours a night, according to the National Center on Sleep Disorders Research, a division of the federal National Institutes of Health. In fact, a 2009 University of Michigan research article published in Nature Reviews Neuroscience suggests that one of the reasons mammals sleep at night is to build up immunity and fight off disease.
In a 2009 Carnegie Mellon University in Pittsburgh study, researchers exposed 153 men and women to a cold virus. Those who had slept an average of eight hours or more a night during a two-week period were three times less likely to develop a cold than those who had slept less than seven hours.
5. Move that body.
Compared with couch-sitters, people who engage in regular, moderate exercise have increased immunity to viruses and other illnesses.
People who exercise moderately for at least 45 minutes most days of the week have about half the sick time as those who don’t, according to research cited by the American College of Sports Medicine.
Just don’t overdo it: Compared with recreational runners, people who run marathons are more susceptible to colds and other infections.
Athletes are more likely to develop an upper-respiratory-tract infection after intense training or competitions, according to a 2009 review of 30 studies involving 10,000 subjects, published in the British Medical Bulletin.
Sure, it’s easier said than done. But emotional stress can cause physical damage.So if you want to boost your immunity, you need to incorporate a stress-reduction program into your life, says Robert Anderson, M.D., author of Clinician’s Guide to Holistic Medicine (McGraw-Hill).
In a classic study, Carnegie Mellon psychologist Sheldon Cohen, Ph.D., interviewed 400 healthy adults about their stress levels and then exposed them to a cold virus. Those who reported higher levels of stress were twice as likely to get sick. (In a 2006 follow-up, Cohen found that those who exhibited a “positive emotional style” were less likely to catch colds.)
Here are a few of the most effective ways to reduce stress:
Meditation. When a University of Wisconsin study had 25 people meditate daily for eight weeks, they had a significantly greater immune response to the flu vaccine than non-meditators.
A similar 2008 Loyola University of Chicago study showed that daily meditation enhanced immune function in women newly diagnosed with breast cancer.
Sociability. Does having fewer friends mean fewer colds?
In a 1997 study, Cohen found that people who spent more time in social activities had less risk of getting sick, even when exposed to a cold virus.
Of course, embracing immune-boosting activities won’t completely protect you against colds, flu and other illnesses.
But by incorporating one or more of these approaches into your life, chances are you’ll feel better and stay healthier.
Health writer Michael Castleman is the author of many books, includingThe New Healing Herbs: The Classic Guide to Nature’s Medicines; Blended Medicine: Combining the Best of Mainstream and Alternative Therapies for Optimal Health and Wellness; and There’s Still a Person in There: The Complete Guide to Preventing, Treating, and Coping with Alzheimer’s Disease.