How Diet May Help to Control Asthma
Asthma is a disease in which the airways in the lungs periodically become inflamed and swollen and the muscles around the airways tighten, making breathing very difficult. Doctors prescribe medications to asthmatics to help them control their disease. Although more research is needed, evidence is slowly growing that eating a healthy and nutritious diet and eliminating foods that are harmful may also help asthmatics to control their disorder. Certain nutrients may be particularly useful.
Any attempts to improve asthma with diet must be accompanied by the use of prescribed medications. Asthma medications are helpful for most people and have proven benefits. The effects of nutrition on asthma aren't as well known as the effects of medications. However, following a healthy diet helps to prevent many health problems and is beneficial for everyone, whether or not they have asthma. If they eat nutritious foods, asthmatics will be able to experience the known benefits of the foods as well as any potential benefits for asthma.
What Happens During an Asthma Attack?
In people with asthma, the lungs are over-sensitive to a trigger that can cause irritated airways. The trigger causes the airways to become inflamed and swollen. Excess mucus is produced and blocks the airways. In addition, the muscles around the airways tighten, making it hard to expand the airways to obtain air.
People with asthma, or asthmatics, don't have a continual breathing problem. The difficulty appears after exposure to a trigger, which produces an asthma attack. There are a variety of possible triggers, including allergens, airborne irritants, chest infections, exercise, temperature changes in the air, food additives, certain medicines and stress.
A Doctor Discusses Asthma
Many asthmatics can restore their breathing during an asthma attack by using a rescue inhaler, which is also called a reliever inhaler. The medication in the inhaler is traditionally delivered in a blue canister.
Asthma is controllable but not curable. Asthmatics frequently take a daily corticosteroid medicine, which reduces inflammation in their airways and often prevents asthma attacks. As the doctor in the video on the right says, when asthma is under control an asthmatic should be able to do everything that a non-asthmatic can do, including exercise.
Unfortunately, sometimes an asthma attack is so severe that prescribed medications don't help. This is a medical emergency. In addition, some people don't get as much help from prescribed asthma medications as others do.
Of course, asthmatics appreciate medications that restore their ability to breathe and prevent asthma attacks. I certainly do! All medications have potential side effects, though. In addition, some asthmatics go through periods when their asthma is not under control and they have more or worse asthma attacks than usual. It would be very nice to have an additional way to protect the airways. Diet might be one of these ways.
Officially, there is no such thing as an "asthma diet". However, asthma experts do say that a healthy diet is best for asthmatics and that eating certain types of foods or avoiding others may help the condition.
Insoluble and Soluble Fiber
Some exciting new research suggests that eating soluble fiber may help asthma. There are two main types of fiber in foods - insoluble and soluble. Each has its own health benefits. Most foods contain a mixture of insoluble and soluble fiber, but some have more of one kind of fiber than the other.
Insoluble fiber doesn't dissolve in the water inside the digestive tract. It stays mainly intact as it moves towards the rectum, the chamber at the end of the intestine where the feces is stored. Insoluble fiber binds to water molecules and speeds up the movement of food through the digestive tract. It also makes the feces bulkier and softer. This prevents constipation. Insoluble fiber may decrease the risk of colon cancer, although the evidence for this is mixed. Some research shows benefits while other research shows none.
Soluble fiber dissolves in water to form a gel in the digestive tract. It slows digestion and can reduce spikes in blood sugar after eating. People who eat lots of soluble fiber tend to have lower blood cholesterol levels than other people.
Grains, legumes (or pulses), fruits, vegetables and nuts contain both soluble and insoluble fiber. Some foods in these categories are known for their high soluble fiber content, however. Barley and oatmeal are two of these foods. Others are lentils, peas, beans, carrots and pears.
Effect of Soluble Fiber on Mouse Airways
Soluble fiber and airway inflammation in mice
Soluble Fiber, Short Chain Fatty Acids and Asthma
Some interesting research from the University of Lausanne has shown that a diet high in soluble fiber reduces both sensitivity to irritants and inflammation in the lungs of mice. These two processes occur at the beginning of an asthma attack in humans. The researchers suspect that soluble fiber also reduces irritation and inflammation in human lungs, decreasing the chance of an asthma attack.
The mice in the Swiss experiment were divided into two groups. The mice in one group were given a diet that was high in soluble fiber while the mice in the other group were given foods that were low in soluble fiber.
Bacteria in the digestive tract of the mice fermented the soluble fiber that they ate, changing it into SCFAs, or short chain fatty acids. These fatty acids then entered the bloodstream. The mice that were fed more soluble fiber produced more SCFAs.
The researchers say that the SCFAs stimulated the immune system of the mice, making their lungs more resistant to irritation and reducing inflammation due to allergies. The mice with fewer SCFAs from soluble fiber developed more allergic airway disease.
Observations from experiments with mice aren't necessarily true for humans too, but they often are. Interestingly, the researchers found that mice who ate a lot of soluble fiber had a change in the composition of the bacterial community living in their gut. Research in humans is revealing many beneficial effects of gut bacteria on our lives.
Nutrients That May Help to Control Asthma - References
Vitamins and Asthma Risk
Including adequate amounts of vitamins C and D in the diet may benefit asthmatics, although the research results aren't conclusive. It's definitely worth paying attention to the investigations, however.
In one research project, scientists found variable benefits of vitamin C for children who had asthma. "Benefit" was determined by measuring the forced expiratory volume per one second (FEV1).
Younger children (aged 7.0 to 8.2 years) who had not been exposed to molds or dampness recently showed the greatest benefit from vitamin C supplementation. Their FEV1 increased by 37%. Older children (aged 8.3 to 10 years) were also tested. Those who had been exposed to molds or dampness in their bedroom for more than one year before the study experienced the smallest benefit from the vitamin supplementation. Their FEV1 increased by 21%.
Other experiments have also found that vitamin C has benefits for asthmatics. However, some experiments have shown no benefits. Large clinical trials are needed to get a clearer picture of vitamin C's effects.
In 2013 some British researchers published some interesting discoveries regarding the effect of vitamin D on asthma. The inflammation that develops in asthmatics in response to a normally harmless stimulus is thought to be caused by a malfunctioning immune system. The researchers studied the effect of vitamin D on the production of an inflammatory molecule called IL-17A by white blood cells. This molecule is thought to be associated with the malfunctioning immune system. In lab equipment, the researchers observed that vitamin D reduced the amount of IL-17A produced by white blood cells that came from asthmatics, including those with severe, hard to control asthma.
Unfortunately, the fact that vitamin D has an effect on isolated cells doesn't mean that it will have the same effect inside our body. The vitamin might be helpful, though. Clinical trials are needed to prove that vitamin D can be useful for asthmatics.
Other Dietary Factors That May Affect Asthma
Other nutrients may improve asthma, but the evidence is very mixed. Nutrients in this category include beta-carotene, vitamin B6 and magnesium. Omega 3 fatty acids that come from oily fish such as salmon and sardines may also be useful.
Nutritionists generally recommend that we get our nutrients from our diet rather than from supplements whenever possible. If someone decides to take supplements to see if they help asthma, it's very important to be careful about the dose. The dose needs to be high enough to be beneficial but not so high that it's dangerous. It's safer to get nutrients by eating a wide variety of whole foods.
Food Allergies or Reactions
Some foods can trigger allergic reactions, which may sometimes include asthma as a symptom. Common food allergens include peanuts, tree nuts, dairy foods, soy, eggs, wheat, fish and shellfish. Food additives such as sulphites and benzoic acid can also trigger asthma in sensitive people.
It's important that anyone who thinks that they might have a food allergy visits a doctor for confirmation. Eliminating a healthy food from the diet unnecessarily would be very unfortunate.
If you think you're allergic to a healthy food, see a doctor for confirmation before permanently eliminating the food from your diet.
What is GERD?
People with asthma quite often have GERD, which may be a cause or a contributor to asthma. GERD, or gastroesophageal reflux disease, is a disorder in which the acidic contents of the stomach move upwards into the esophagus, irritating the oesophageal wall and causing a burning sensation known as heartburn. The condition is similar to acid reflux disease. Generally, if someone has acid reflux more than twice a week they are said to have GERD.
GERD arises due to the misbehavior of a ring-shaped muscle called the lower esophageal sphincter, or the LES. This muscle is located at the junction between the esophagus and the stomach. Normally, once food has entered the stomach, the LES closes the junction. If the LES doesn't completely close the junction or if it opens the junction when the stomach is full, the stomach contents can enter the esophagus.
GERD is often triggered by certain foods and drinks. Some of these include tomatoes, citrus fruits, fatty or spicy foods, chocolate, mint, onion, garlic, carbonated beverages, coffee, tea and alcohol. Food sensitivites are quite individualized in GERD, however. A food or drink that causes acid reflux in one person may have no effect on another person.
The Relationship Between GERD and Asthma
How Does GERD Cause Asthma?
It's not known for certain how GERD causes an asthma attack. One possibility is that the acid that enters the esophagus during reflux gets into the throat and then irritates the breathing passages. This may cause an asthma attack or make the body more susceptible to another asthma stimulus.
It's also possible that acid in the esophagus triggers a nerve reflex that narrows the airways to help prevent acid from entering them. This may cause difficulty in breathing and make asthma worse.
Obesity and Asthma
A diet, lifestyle or medical problem that leads to obesity can also lead to asthma. There are many reports of obesity increasing the incidence of asthma, severe obesity increasing the risk of severe asthma and weight loss in obese people improving asthma.
Why does obesity trigger or worsen asthma? There are several possible reasons. It's known that obesity increases overall inflammation in the body, which may include the airways. Obese people also have a smaller lung capacity than people of normal weight. In addition, obesity increases the risk of GERD.
Components of a Healthy Diet For Asthmatics and Other People
According to most nutritionists, a healthy diet should emphasize whole foods from plants and be low in saturated fat, trans fats, salt and added sugar. Recommended components of the diet generally include:
- whole grains
- legumes (pulses)
- low-fat dairy products
- fish (especially those that contain omega-3 fatty acids)
- lean meat
- nuts and seeds
- olive oil
- herbs and spices
- green tea
Of course, if someone has been diagnosed as allergic or intolerant to a food, or if someone has an ethical objection to eating a certain type of food, that food would have to be eliminated from the diet and, if possible, replaced by a similar substitute.
Benefits of a Healthy Diet For Asthmatics
A healthy diet that is high in whole, unprocessed plant foods reduces the chance of serious health problems, such as heart attacks, strokes, cancer, type 2 diabetes and osteoporosis. It's an excellent diet for everyone.
Even if the nutrients in food don't reduce asthma attacks directly, they may well prevent them indirectly. It's known that a healthy diet boosts the activity of the immune system. A strong immune systems stands a better chance of fighting and preventing infections that cause respiratory problems. Illnesses such as the flu and the common cold can lead to asthma attacks in susceptible people. In addition, preventing unhealthy weight gain gain and obesity with a suitable diet can help to reduce asthma.
Most asthmatics are well aware of their personal asthma triggers. For example, mine are dust mites, the inhalation of cold air and the presence of respiratory infections. An asthmatic should avoid their personal triggers for asthma, even if they're following a healthy diet, and continue to take any prescribed medications to reduce lung inflammation. A healthy diet might provide extra protection against asthma attacks, however, and might even enable less medication to be taken. Prescribed asthma medication should never be reduced or stopped without a doctor's advice, however, since asthma can be deadly.
A healthy diet is beneficial for everyone, including asthmatics, even if diet doesn't have a direct effect on asthma risk.
Does Following a Healthy Diet Help Asthma?
I control my asthma with the daily use of an inhaler containing a corticosteroid to prevent inflammation in my lungs and a bronchodilator to keep my airways open (Symbicort). This medication generally works well for me.
I try to follow a healthy diet with lots of whole foods. I do notice that if I go through a period when my diet is less healthy my asthma gets worse and I have to use my controller inhaler more often, as my doctor told me that I could do if necessary. I sometimes have to use my rescue inhaler as well.
I don't know why a healthy diet helps me. It may be due to the increased level of soluble fiber in my diet, as the Swiss researchers suggest, or it may be due to a completely different factor (or factors) in my diet. The improvement in my asthma may even be due to a non-dietary factor. My diet tends to deteriorate when I am very busy and when I don't get enough sleep. The stress or lack of sleep may be responsible for my worsening asthma under these conditions.
A healthy, nutrient-rich and high fiber diet is very worthwhile due to its many benefits, even if it has no effect on asthma risk. If it does reduce the number or severity of asthma attacks, that's an additional advantage!
Asthmatics should always follow their doctor's suggestions for controlling their disorder. Following a whole food diet that includes soluble fiber and a wide range of nutrients is an extra step that is worth taking, however. It can improve the functioning of the immune system, help to maintain health and perhaps even improve asthma.
© 2014 Linda Crampton
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