Asthma, Allergies and Nutrition - The Story
February 18, 2019
This is a chapter that I wrote for an Integrative Medicine Textbook on Allergy and Asthma. I will break it up into parts for your consumption. It is mostly unaltered from its original form which means at points it is quite technical, however, the gist is there and I hope that it provides a roadmap to health for allergy and asthma sufferers.
• Asthma is now well known to be an inflammatory disease based on the response to anti-inflammatory medications and pathophysiological evidence making it a prime candidate for anti-inflammatory nutritional interventions.
• The Standard American Diet is filled with pro-inflammatory highly refined and processed foods that are laden with excessive amounts of sugar and unhealthy fats thus promoting inflammatory pathways that exacerbate disease.
• The genesis of the inflammation is now believed to start in part in the intestinal and pulmonary microbiomes with the loss of immune tolerance. The intestinal microbiome is highly responsive to whole food dietary alterations.
• We will discuss in depth the food choices that lower the inflammatory burden, the asthma phenotype and the food immune reactions that exacerbate disease.
Historical medical training over the past half century has focused on asthma as an allergic disease that is predominantly only modifiable through allergic trigger avoidance and pharmaceutical medical therapy. Physicians were never trained to focus on diet or nutrition as a tool for disease remediation. Frankly, it was scoffed upon to worry about a patient's sticky bun habit as means to modify their symptoms. However, science has created a new working understanding of asthma as a modifiable disease with the discovery of the epigenome, microbiome, metabonome and nutrigenome.
In order to understand how food will and does effect asthma, the understanding of the first principles root cause of asthma is critical. Asthma is an inflammatory disease that has its genesis very early in life when a person develops a disruption of immune tolerance. This disruption occurs for many reasons; however, the leading theory is the Biome Depletion Theory which has improved upon the earlier Hygiene Hypothesis that Strachan et. al. discussed in the 1990's.(Stiemsma et. al. 2017) This theory basically states that the loss of co evolving microbes, especially helminths/parasites, has put a strain on the ability of the immune system to develop natural tolerance to non-pathogenic protein epitopes from foods, plants, dust, animals, etc.
The prototypical study that looked at this reality was published in 2016 and looked at house dust microbial cell wall endotoxin levels in the genocentric communities of the Amish and Hutterite enclaves in the United States. The measured dust endotoxin level was used as a marker of microbial coevolution from birth. The Amish community lived very intimately with their animals as the children spent much time from birth on exposed to animals in their immediate vicinity. Contrast this with the Hutterite community where the children lived peripherally on a mechanized centralized farm. They were rarely exposed to the farm animals. This differential exposure to the animals gave the Amish children a roughly 7 times higher microbial exposure then their Hutterite brethren throughout their lives. Statistically, the study showed that the Amish offspring had a 4X fold lower risk of developing asthma and allergic sensitization. They posited that the lack of microbial exposure was driving the disease in the Hutterite children.(Stein et. al. 2016)
The researchers furthered the evidence of causation and not just association by exposing asthma prone mice to the respective endotoxin laden house dust from both communities. What they found was remarkable. The dust exposure dictated whether a mouse developed the disease phenotype that we call asthma. The Amish dust exposed mice did not develop asthmatic disease paralleling the human data of disease risk.(Stein et. al. 2016)
Knowing that a failure of early microbial exposure is compounded by over clean home environments, cesarean section birth deliveries, antimicrobial drug use and a lack of breastfeeding, the science is now proving that the long-term effect is to develop an abnormal intestinal microbiome that allows the interface between the outside world, i.e. food and the immune system to be compromised. The actual process by which this happens immunologically is beyond the scope of this chapter.(Stiemsma et. al. 2017)
Essentially, there is a cross talk between the microbes of our lungs and gut and our immune cells that is disrupted leading to abnormal recognition of food protein epitopes leading to antibody responses primarily in the IgE class as in food allergy and the IgG, IgG4, IgA classes for food sensitivity/intolerance. There is also a solid body of growing evidence that beyond the humoral immune system's response there is an innate immune response to intestinal and pulmonary microbial peptides driving low grade endotoxemia that is seen as inflammation.(Cani et. al. 2009)
This latter point is likely a major player in the inflammatory process of humans as it is well known that highly processed foods laden with sugar and saturated fats drive the intestinal microbiome to a dysbiotic gram negative rod predominant enterotype.(Moreira et. al. 2012)(Stokholm et. al. 2018)(Stiemsma et. al. 2017)(Weng et. al. 2013)
The story continues next week,
Stiemsma AACI Article
Stein NEJM Article
Cani Current Opinions Pharmacology
Moreira British J Nutrition
Stokholm Nature Communications Article
Weng J Develop Origins Health Disease Article