Asthma is an inflammatory disease characterised by recurring attacks of narrowed, swollen airways, causing shortness of breath, wheezing, and coughing. Some 235 million people worldwide suffer from asthma, and it is the most common chronic disease among children.
Per the World Health Organization, the fundamental causes of asthma are not completely understood. They state the strongest risk factors for developing asthma are a combination of genetic predisposition with environmental exposure to inhaled substances and particles that may provoke allergic reactions or irritate the airways (see here).
But can the food we eat have any effect on asthma? Can eating a more plant-based diet make a difference? Yes, it can. I’ve written previously here on the topic of inflammation and how meat-based dietary patterns were associated with more inflammation, while vegetable and fruit-based diets were associated with less. Asthma is a state of increased oxidative stress in our airways, and so it makes sense that an anti-oxidant rich diet may help. Furthermore, it has been observed that food of animal origin has been associated with increased asthma risk (the arachidonic acid in animal products may be a contributor – see here).
In his book The Cheese Trap, Neil Barnard, MD states that in his view, it is not entirely clear why avoiding diary products is often so helpful for inflammatory conditions, including asthma. He wonders if the protein in dairy may be the cause. He writes that perhaps the human immune system recognizes dairy protein as foreign and launches an inflammatory assault to try to eliminate it. He notes that when allergens trigger the production of antibodies, it takes weeks for them to dissipate. Therefore studies, and experimentation in our own lives, needs to take this into account when assessing whether or not the removal of dairy from the diet is effective.
Here’s a look at the results of some of the particularly interesting interventional studies:
- Placing subjects with asthma on a low antioxidant diet (≤2 servings vegetable plus one serving of fruit/day) led to a significant worsening of lung function and asthma control score (reference here). Sadly, the low antioxidant diet reflects our current Western diet.
- In the same study it was shown that increasing fruit and vegetable intake to 7 servings per day reduced asthma exacerbation rates in half.
- Another study involved going the whole nine yards and switching severe asthmatics to a plants-only diet for a year. These subjects had on average a 12-year history of the disease and all received long-term medication for it. For the 24 subjects who maintained the diet, 90% reported improvement after a one-year period. There was a significant improvement in a number of clinical variables. And, more impressive still, in almost all cases, medication was withdrawn or drastically reduced.
- A pilot study of asthmatic children put on a milk- and egg-free diet for eights weeks showed a 22% improvement in lung function.
While we wait for larger and more robust research to be done, we can always just give eating more plants a try to see if it helps. The only side-effects are positive ones!