Asthma
Opening Up for Easier Breathing
Want to know exactly what asthma feels like?
"Pinch your nose shut and breathe through a straw," suggests Nancy Sander, president of the Allergy and Asthma Association/Mothers of Asthmatics. Then try climbing a flight of stairs or chasing after something fast--say, a frisky toddler. You'll soon be gasping for air the way someone with asthma does during an attack. "It's a frightening experience," Sander says.
The usual setup for an attack combines an allergic (or supersensitive) immune system, an inherited trait, with exposure to environmental allergic triggers such as animal dander, mold spores and pollen or to environmental irritant triggers such as air pollution, cold air and cigarette smoke. Other activators can include respiratory infections, colds, laughter, crying, anger, exercise and stress.
There are two major components of asthma. One is noisy--the wheezing, coughing, choking, can't-catch-your-breath feeling. That's the part most people call an asthma attack, or bronchospasm and congestion.
The second part of asthma is quiet. It is called inflammation--the part of asthma that is always present but not always noticed. Just as a sunburn may not be evident until long after you've come in from the sun, airway inflammation is not noticeable until the damage has become so extensive that an asthma attack begins.
During an asthma attack, the muscles surrounding the lungs' bronchial tubes contract, narrowing airways and making it hard to breathe.
People with chronic asthma also have inflammation in their lungs. The membranes lining the inner walls of the air passages become swollen and leaky. And the glands within these walls produce excess mucus. "That makes it harder for the lungs to do their job of gas exchange, picking up oxygen from the air and dumping carbon dioxide out the body," explains Ronald Simon, M.D., head of the Division of Allergy and Immunology at Scripps Clinic and Research Foundation in La Jolla, California.
Asthma is usually treated with drugs that open airways and reduce inflammation as well as by avoiding substances that trigger attacks. For some people, that means finding a new home for a family pet, exchanging the wall-to-wall carpeting for linoleum or steering clear of cigarette smoke, car and truck exhaust and chemical fumes.
Dietary counseling for asthma, especially in young children, may include testing for possible problem foods. But it doesn't often include recommendations for vitamin or mineral supplements, experts say.
Nevertheless, some research suggests that certain nutrients may play roles in asthma by reducing airway sensitivity and dampening inflammation.
Here's what research shows. (Note: If you're feeling well enough to reduce your dosage of asthma medication, do so only under medical supervision, experts warn. Stopping asthma drugs abruptly could lead to problems.)
Magnesium Makes a Difference
"Magnesium has properties that may help people with asthma," says John Britton, M.D., a senior lecturer in the respiratory medical unit at City Hospital in Nottingham, England.
This essential mineral helps reduce inflammation by stabilizing immune cells--mast cells and T lymphocytes--so that they are less likely to break down and dump their irritating contents in the lungs, Dr. Britton explains. It also helps the body eliminate certain lung-irritating chemicals. And magnesium helps produce anti-inflammatory biochemicals, called prostacyclins, in the body.
"All of these functions could help relieve congestion, constriction and hypersensitivity in people with asthma and other lung problems," Dr. Britton says.
A study by Dr. Britton and his colleagues found that people who got about 480 milligrams of magnesiuma day from foods could expel more air from their lungs than people getting only about 200 milligrams of magnesiuma day. (The volume of air that can be expelled is considered an important indicator of healthy lungs.) People getting the larger amount of magnesium were also twice as likely to be able to tolerate the maximum dose of an airway-constricting spray, Dr. Britton says.
"Further studies are needed to confirm that magnesium can help control asthma," Dr. Britton says. But he and other researchers agree that it's a good idea to get the Daily Value of magnesium, which is 400 milligrams. Studies show that most people fall short.
"I recommend a diet of whole, unprocessed foods such as nuts, beans and whole grains," Dr. Britton says. He also suggests "a pint a day of stout, another good source of magnesium." Actually, he adds, any beer will do.
If you are considering trying magnesium supplements, be sure to check with your doctor first if you have heart or kidney problems.
Interestingly, magnesiumis sometimes given intravenously to treat serious asthma attacks. Large doses of magnesiumrelax the muscles around blood vessels and airways. Intravenous magnesiumis helpful for a person having a life-threatening asthma attack called status asthmaticus, which does not respond to the usual drugs. Apparently the trick is to get the magnesium into the body fast, say doctors from Wilford Hall Medical Center in San Antonio, Texas.
| Food Factors Reactions to protein or additives in certain foods are the strongest links between asthma and food. Additional factors such as salt and caffeine may also play roles. Here's what you need to know. Aim for an ideal body weight. "People with asthma who are overweight have trouble breathing. The extra weight makes it more difficult for them to breathe, especially when they exert themselves, because of the abdomen pressing against the diaphragm," explains dietitian Lana Miller of the National Jewish Center for Immunology and Respiratory Medicine in Denver. "The number one issue is being at a good weight. It's a concern for 95 percent of all people with asthma." People taking oral steroids need to be particularly vigilant against weight gain, she says, since these drugs can stimulate appetite and cause fluid retention. Beware the guacamole. Thanks to laws that require sulfites to be listed on labels, it's fairly easy these days for people with asthma to avoid this potentially deadly food preservative. Dried or canned fruits and vegetables, instant food mixes and wine are the store-bought foods most likely to contain large amounts of sulfites, says Martha White, M.D., director of research and pediatrics at the Institute for Asthma and Allergy at the Washington Hospital Center in Washington, D.C. It's still possible, however, to get unsuspected sulfites. Potatoes, shellfish, shrimp, salads and guacamole (avocado dip) are often treated with sulfites. And imported beers and wines may not list sulfites on their labels, Dr. White says. "People are most likely to be unexpectedly exposed to sulfites when eating out," she says. This is because they have no control over food processing or preparation. Call ahead to find out which, if any, foods on a restaurant's menu contain sulfites, she suggests. Stay away from salt. People taking oral steroid drugs for their asthma may need to monitor their sodium intakes because of problems with fluid retention, says Miller. Your best strategy for cutting back on salt is to avoid processed foods. "Foods with more than 400 milligrams of sodium per serving are considered high-sodium items," says Miller. Canned soups, packaged macaroni and cheese, cottage cheese and lunchmeats are all high in sodium. Switch to fish.The oil in fatty fish such as mackerel, salmon and swordfish has anti-inflammatory effects that may help some people with asthma. In a study by British researchers, people with asthma who took 18 capsules of fish oil a day had fewer breathing problems a few hours after being exposed to a symptom-inducing inhalant. Some doctors suggest that each week, you simply replace a meal or two of beef or poultry with fish. Know your trigger foods.Some people, especially children, have asthma attacks soon after eating foods such as peanuts or other nuts, eggs, fish, shellfish, milk, soy, wheat or bananas, says Dr. White. People who believe they have such food allergies--or who eliminate certain foods from their children's diets in the hope of improving symptoms--should make sure their diets remain balanced, she emphasizes. "If you are eliminating dairy products, for instance, it's important to take calcium supplements," she says. Drink your milk. Unfortunately, some parents still adhere to the old myth that milk and dairy products create mucus in the lungs, says Miller. There is simply no valid reason to deprive children with asthma of these foods, which are so important for building healthy bones, she admonishes. |
Vitamin C May Ease Wheezing
People with asthma sometimes take supplements of vitamin Cbecause they believe in its legendary virus-fighting powers. There's some proof that vitamin C does indeed reduce the duration and severity of colds, an important benefit for people with asthma, whose symptoms often worsen with respiratory infections.
But vitamin C may do more than ease sneezing and sniffles.
A study by researchers at Harvard Medical School found that smokers who got at least 200 milligrams of vitamin C(three oranges' worth) a day had a 30 percent reduced risk of bronchitis or wheezing compared with people who got about 100 milligrams of the vitamin a day.
Another study by the same researchers found that vitamin Chelps maintain healthy lungs. People getting about 200 milligrams of vitamin C a day did best on tests that measured their lungs' capacity to expand and draw in oxygen.
"This study suggests that a high dietary intake of vitamin C-rich foods is associated with improved levels of lung capacity," says study co-author Scott Weiss, Ph.D., associate professor of medicine and associate physician in the Channing Laboratory at Brigham and Women's Hospital in Boston. "Getting enough vitamin C may prove to play an important role in reducing your risk of chronic lung disease, including asthma."
In several other studies, taking vitamin C well before symptoms appeared reduced people's tendency to have asthma attacks while exercising.
Vitamin C may protect the lungs in a number of ways, says Vahid Mohsenin, M.D., a researcher in the John B. Pierce Laboratory at Yale University.
First, it helps shield lungs from the damaging effects of chemicals in smoke or smog-laden air. It neutralizes these chemicals so that they can't hurt cells. That's important, because exposure to air pollution often makes asthma worse, Dr. Mohsenin says. Vitamin C can also neutralize the harmful chemicals produced by the body as a result of the inflammation that occurs with asthma, helping to prevent a vicious cycle of increasingly severe attacks.
Vitamin C also seems to act as a natural antihista mine, which means that it helps reduce the lungs' sensitivity to histamine, a biochemical released by cells during allergic reactions. "Vitamin C also reduces lung sensitivity to methacholine, a biochemical that causes airways to constrict," Dr. Mohsenin says. And vitamin C interferes with the body's production of prostaglandins and leukotrienes, two potentially harmful biochemicals that can promote inflammation and constriction of the airways, he says.
Doctors recommending vitamin C to their patients with asthma who exercise prescribe 500 to 1,000 milligrams a day. That amount is considered well within the safe range, but higher doses can cause diarrhea in some people.
| Prescriptions for Healing Most doctors use drugs, not vitamins and minerals, to treat asthma. Those who do provide nutritional therapy usually combine it with drugs and with avoiding exposure to substances that can trigger an asthma attack. These are the nutrients that some doctors recommend. Nutrient Daily Amount
Beta-carotene25,000 international units Magnesium400 milligrams Niacin100 milligrams Selenium100 micrograms Vitamin B650 milligrams Vitamin C500-1,000 milligrams Vitamin E800 international units
MEDICAL ALERT: If you have asthma, you should be under a doctor's care. If you're feeling well enough to reduce your dosage of asthma medication, do so only under medical supervision, experts warn. Stopping asthma drugs abruptly could lead to problems. If you have heart or kidney problems, you should check with your doctor before taking supplemental magnesium. It's a good idea to talk to your doctor before taking the amount of vitamin Erecommended here. If you are taking anticoagulant drugs, you should not take vitamin E supplements. |
Antioxidants Shield Lungs
Researchers who say vitamin Cis helpful for asthma point out that other nutrients with similar antioxidant properties could be beneficial. These nutrients include vitamin E, seleniumand beta-carotene, a yellow pigment found in carrots, cantaloupe and other fruits and vegetables. "Laboratory work indicates that all three help reduce inflammation-producing biochemicals," says Dr. Simon.
So far, however, only one study has actually looked at any of these nutrients as supplements for people with asthma. In that study, by researchers in Sweden, people with asthma who took 100 micrograms of selenium daily for 14 weeks had stronger lungs and were less sensitive to airway-constricting inhalants than when they were taking placebos (dummy pills).
Seleniumis needed in the body to produce glutathione peroxidase, an enzyme that helps protect cells by breaking down biochemicals associated with inflammation.
"It's too soon to say for sure whether supplementing a regular diet with selenium will help people with asthma," Dr. Simon says. People who want to try it can safely take 100 micrograms, the amount found beneficial in the Swedish study, he says. (The Daily Value is 70 micrograms.)
Studies have shown that people generally get about 100 micrograms a day from the average healthy diet. Don't overdo it with selenium, say nutrition experts. A daily intake of 200 micrograms from foods and supplements is considered the upper limit of the safe range.
People who want to take other antioxidant nutrients can safely supplement with up to 800 international units of vitamin Eand 25,000 international units of beta-carotenea day, Dr. Simon says. It's a good idea to talk to your doctor before taking more than 600 international units of vitamin E daily.
Bs to the Rescue
Some B vitamins--notably vitamin B6and niacin--have also been reported to help people who have asthma. One study of children with asthma found that doses of 100 or 200 milligrams of B6 a day dramatically reduced the frequency, duration and severity of asthma attacks. A later study, however, conducted by researchers at the National Jewish Center for Immunology and Respiratory Medicine in Denver, found that adults with severe asthma did no better while taking 300 milligrams of B6 than a similar group who were taking placebos.
Still, some doctors recommend 50 milligrams of supplemental vitamin B6 a day for their patients with asthma. And one study by researchers in South Africa found that people taking theophylline, a common asthma drug, along with 15 milligrams of B6 a day were less likely to suffer from the side effects of the drug--irritability, anxiety and faintness. Doses of more than 100 milligrams of B6 a day can cause nerve irritation, so don't take more than that amount without medical supervision.
Several studies have observed that niacinsupplements reduce the incidence of wheezing, perhaps because this nutrient prevents the release of histamine. Harvard University researchers, for instance, found that people who got the most niacinin their diets were significantly less likely to have bronchitis or wheezing than people who got the least. In addition, lower blood levels of niacin were linked to increased wheezing.
Doctors who recommend niacin to their patients with asthma suggest about 100 milligrams a day.
Some studies suggest that in addition to the nutrients mentioned above, calcium, zinc, copperand vitamin D may all play supporting roles in easing the symptoms of asthma. Whew! "There's no doubt in my mind that people with asthma can do better in the long run if they eat a healthy diet," says Sander.
