There really is no asthma diet, per se. However, according to some studies, there do seem to be certain foods/drinks/nutrients that favor better asthma control. Here are some that have been extensively studied and what has been learned.
Coffee was first recommended for asthma in the 1850s by Dr. Henry Hyde Salter. His theory about asthma was that it was a nervous condition that could be brought on by sleepiness. So, he figured the stimulant effect of coffee warded off asthma. Today we know that coffee is from the same family of plants as theophylline, a bronchodilator commonly used to treat asthma in the 1970s and 80s. When caffeine is metabolized, it breaks down into a small dose of theophylline, which in turn opens airways. So, this may explain why coffee, known as containing high amounts of caffeine, may help improve asthma control. Other things that contain caffeine include tea, energy drinks, fountain drinks like colas and Mountain Dew, and cocoa beans (meaning chocolate).
Various studies have linked vitamin D deficiency with more persistent asthma and worsening asthma control. Of course, those with poorly controlled asthma may spend more time indoors by default, and this may result in diminished Vitamin D levels. However, some studies show that as many as a third of all children in western nations have low vitamin D levels, and this may be explained by spending more time indoors watching TV and playing on gadgets, wearing sunscreen, and eating diets low in vitamin D. Whatever the reason, researchers think Vitamin D plays a role in the maturation of the immune system. So, low vitamin D levels may help instigate that overactive immune response and the release of chemicals that induce asthma symptoms, while adequate vitamin D levels may act to suppress this effect. While studies are ongoing in this regard, one can’t help but think that vitamin D supplementation may result in better asthma control (and some studies do seem to indicate that it does). Foods that contain vitamin D include dairy products such as cheese and milk, fatty fish, fish oils, and cereals. 1,4
These are substances that are produced when your body breaks down vegetables and fruits. Studies show that they block the release of chemicals responsible for allergies and asthma and result in better asthma control. They are also antioxidants that prevent free radicals from damaging cells and causing asthma and COPD symptoms. Pretty much all of the plant-based foods contain flavonoids, including vegetables, fruits, and nuts. They are also abundant in fruit and vegetable juices, tea, and red wine. Some of these have been extensively studied. For example, one study showed that apples.5
It may help reduce asthma symptoms in the same way it helps make cold symptoms less severe. In fact, one study showed that taking vitamin C 1-1.5 hours before exercise reduced symptoms due to exercise-induced bronchospasm. Another showed that vitamin C reduced asthma symptoms in general. There’s a couple theories explaining how this works. One is that it contains antioxidants, and these have been shown to prevent free radicals from causing oxidative stress and damaging airway cells)s, something that has been implicated in causing asthma and COPD. A second theory suggests that the chemicals released after exposure to a virus are the same as those released when you’re exposed to your asthma triggers. Vitamin C is thought to suppress the effects of these chemicals. Vitamin C is found in citrus fruits such as oranges, kiwi, limes, grapefruits, and also in their juices. They are also found in strawberries, brussels sprouts, broccoli, tomatoes, and potatoes.6,8
Studies have shown that vitamin E, like vitamin C, suppresses the immune response responsible for airway inflammation and contains antioxidants that prevent free radicals from damaging cells in a way that causes asthma symptoms. In one study, the antioxidant found in vitamin E (gamma-tocopherol) was tested on asthmatics diagnosed with neutrophilic asthma, a subgroup of asthma considered as severe asthma. The study showed that those who took gamma-tocopherol had lowered neutrophil levels and less airway inflammation compared to a control group. Researchers concluded that gamma-tocopherol vitamin E has potential as not just a potential treatment for asthma, but for cystic fibrosis and COPD as well. Foods high in vitamin E include nuts, seeds, vegetable oils, and green leafy vegetables like broccoli, asparagus, peas, and spinach. 7,9,10
Beta-carotene and vitamin A
It’s a pigment found in colorful vegetables that gives them their color, such as carrots, sweet potatoes, kale, peppers, winter squash, cantaloupe, mango, and dark green leafy vegetables. It contains antioxidants, and it’s also converted to vitamin A, which has also been shown to improve asthma control.11,13
Omega 3 Fatty Acids
Low asthma rates were observed in the Eskimo community. Eskimos eat lots of fish. Fish contains omega 3 fatty acids. A theory arose that omega 3 fatty acids protect against the effects of asthma, and this inspired researchers to perform studies. However, a review of all these studies failed to prove this theory. It does not rule out the potential here, it just showed that more studies are needed in this regard. Foods high in omega 3 fatty acids include oily fish like salmon, fish oil, flaxseed, flaxseed oil, basil, some spices, broccoli, and spinach.14,15
There are two theories that postulate our modern quest to be clean, the use of antibiotics, and our modern diets may play a role in the higher rates of asthma in western nations like the U.S. Britain, Canada, and Australia. In other words, our quest to wipe out disease-causing bacteria may also wipe out the good bacteria in our bodies, called probiotics. Probiotics are essential to good health. Some theories postulate that probiotic supplementation may result in better asthma control. So, it’s possible, although not proven yet, that probiotic supplementation may result in better asthma control.
It has long been suspected that exercise and a healthy diet can result in improved asthma control. While I have long been a proponent of both, I did not realize the significance of the later until doing research for this post. While studies here are inconclusive, they do seem to show that a diet rich in fruits and vegetables, with the occasional snack or meal that includes nuts, fish, and milk, may help improve your asthma control. This diet may also include fun things like chocolate and even wine. Supplementation with certain vitamins, minerals, and probiotics may also prove helpful.