Does What You Eat Matter?

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Before we discuss the scientific findings relating asthma and diet, there are a couple of scenarios that revolve around eating and asthma worth mentioning.

First, if a particular food triggers asthma, it may be a food allergy. This is especially likely if you also experience other symptoms at the same time, such as abdominal cramping, vomiting, itchy rashes, flushing, face swelling, or throat symptoms. Food allergies are more likely to occur in early childhood upon the introduction of new foods, or with eating a food after a long period of avoidance. A true food allergy is more likely to develop to one of the following food groups: egg, milk, peanut, tree nuts, fish, shellfish, wheat and soy. Finally, it should happen fairly consistently. If there are any questions about whether you have true food allergy, it’s fairly easy and quick to do allergy skin testing in your allergist’s office.

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Second, over-the-counter pain medications such as aspirin, ibuprofen, naproxen can also trigger asthma. This is more likely to occur in patients with a history of asthma and nasal polyps, or small growths that happen in the nasal passage. These drugs together fall within a class of medications known as non-steroidal anti-inflammatory drugs (also known as “NSAIDs”). These reactions can happen anywhere from minutes to hours after ingestion of the drug. They can also cause other symptoms, such as abdominal cramping, flushing, facial swelling, runny nose, and mouth/throat symptoms. When asthma is accompanied by an NSAID allergy and polyps, it falls into a class of asthma known Aspirin Exacerbated Respiratory Disease (AERD).

Third, it might be esophageal reflux. Esophageal reflux is when stomach acid comes up the stomach, and into the esophagus. This typically occurs when a circular muscle, that sits between the stomach and the esophagus, becomes loosened and allows acid to escape and travel up the esophagus. It can be worsened by things such as eating a large meal, which expands the muscle further, or drinking alcohol, which further relaxes the esophageal muscles, or lying down, which allows stomach acid to flow more easily northward. For not entirely clear reasons, reflux is a known asthma trigger.

We can now move to the topic of asthma and diet.
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Asthma is a complex and poorly understood disease. It is likely caused by an alliance of genetic and environmental factors. Evidence suggests that our diet is one of these environmental factors. The diets of our ancestors consisted mostly of nuts, fruits, vegetables, and limited amounts of unprocessed meats. Post-industrialization, and particularly in developed countries, our diets are now high in saturated fat (i.e. fried foods and processed meats), sugar, and processed grains. Supportively, we see that asthma prevalence rates are highest in developed countries (e.g. U.S., Ireland, United Kingdom), while rates area rising in the developing world as they adapt to a Western lifestyle and diet. Lab experiments with mice demonstrate that high fat and low fiber diets worsen airway inflammation.

The reasons to changing diets goes beyond improving asthma control. A Western diet is also known to cause heart disease, diabetes, obesity, and recently, has been connected to chronic obstructive pulmonary disease (COPD). It is indicated in the development of complex inflammatory conditions, such as inflammatory bowel disease. 

Nonetheless, with respect to asthma, here are my recommendations:

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Adapt a diet high in fruits and vegetables, nuts/seeds, and oily fish, as evidence suggests it could be helpful. I typically recommend this diet as the starting point. I also suggest increasing the amount of foods high in Omega-3, while at the same time decreasing those high in Omega-6, i.e. transitioning to anti-inflammatory fats. This means eating more tree nuts and fatty fish, while avoiding or eating less peanuts, processed meats, poultry and eggs.

I do not recommend avoiding dairy, particularly in children. Cow’s milk is high in Vitamin D and Omega-3 (if fortified). Despite common beliefs, there has never been evidence that cow’s milk or dairy products increase mucous production or worsen asthma. In fact, several blinded studies (‘blinded’ means the subject tested is blinded to the food ingested) show that ice cream ingestion made no difference on asthma symptoms or mucous production.

Reduced processed meats.  This includes hot dogs and hamburgers. We obviously have to live our lives, and this doesn’t mean depriving your child a burger among friends. But while countless studies prove these foods are particularly inflammatory, we ask that you don’t eat them every day.

Adopting a diet similar to that of the Mediterranean diet could prove to be very efficacious in helping with the inflammation associated with asthma while also imbuing other beneficial side effects.

For further, in depth reading, here is a very comprehensive paper:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5707699/