How Diet Plays a Role in Asthma Attacks
Some 14.6 million Americans have asthma, a chronic lung problem that causes difficulty breathing, and 5,000 people die from it each year. Most sufferers know the disorder requires medical management, but too few realize that it is not just the symptoms that can be tackled but also many of the causes.
Attacks can be triggered by internal factors such as stress and infections and external factors such as dust, pollen, tobacco smoke and pollution. Whatever the cause, the end result is the same--the lung’s airways swell and tighten, restricting airflow. When this happens, cells lining the lungs’ bronchial tubes release the chemical histamine, which causes inflammation and production of excess mucus, making breathing even more difficult. Avoiding smoky rooms, areas with high pollen counts and air pollution, plus finding ways to combat stress, are sensible ways to tackle such underlying causes of asthma. But a person’s diet may also reduce or increase the likelihood of an attack.
Research has shown that fewer attacks occur in populations that consume large amounts of fruits and vegetables and that asthmatics with low levels of vitamin C in their blood have more problems with wheezing. Scientists suggest this relationship could be attributed to the delicate balance between oxidants and antioxidants in the lung. It is the introduction of excess oxidants, via smoke and pollutants, for instance, that is at the root of an attack.
Vitamin C is the major antioxidant present in the lining of the lungs and appears to reduce the risk of symptoms. Papaya, guava, black currants, green, red and yellow peppers, broccoli, strawberries, kiwi fruit and oranges are not only rich in this vitamin but seem to prevent the release of histamine. Quercetin, a plant nutrient present in onions, apples, kale, broad beans, leeks, tea and berries, has a similar effect, mopping up oxidants and lessening inflammation by blocking histamine. The anti-inflammatory properties of omega-3 fatty acids found in oily fish such as salmon, mackerel and tuna, may also be helpful.
Just as certain foods may help control asthma, others should be avoided when trying to reduce attacks. At the top of the list come foods containing “sulfites,” a term referring to a variety of additives used in food to prevent browning. They may be listed on food labels as sulfur dioxide, sodium sulfite, sodium or potassium bisulfite or sodium or potassium metabisulfite. Whichever the form, in sulfite-sensitive asthmatics, consumption can spark intense reactions.
Although no longer permitted for use in ingredients in restaurant salad bars, sulfites can be found in many packaged foods including dried fruits, dehydrated potatoes and fruit juices, gelatin, maraschino cherries, lemon juice, salad dressings and sauces from dry mixes, shrimp and canned seafood soups, pickled products and canned or dried soups.
Milk and eggs have also been linked to asthma attacks, especially in children. If this is suspected, a careful exclusion diet must be followed under the guidance of a registered dietitian to diagnose the problem, and, if necessary, construct a nutritionally complete milk- or egg-free diet.
While inhalers and steroids remain the drugs of choice to treat asthma attacks, avoiding exposure to internal and external triggers and taking certain nutritional steps may help to reduce the number of attacks experienced in the first place.
*
Amanda Ursell, a dietitian and nutritionist, is a London-based freelance journalist. Her column appears twice a month. She can be reached at amanda@ursell.com.
