Creatine, Asthma and Allergies

Creatine can exacerbate airway inflammation and asthma:

Effect of Creatine Supplementation on the Airways of Youth Elite Soccer Players [2019] https://pubmed.ncbi.nlm.nih.gov/30913162/

Creatine Activates Airway Epithelium in Asthma [2010]

https://pubmed.ncbi.nlm.nih.gov/21072743/

"Inducible nitric oxide synthase (iNOS) is an isoform of NOS, and increases in its expression have been linked to eosinophilic inflammation and airway remodelling in asthma... we found that creatine supplementation was associated with greater epithelial expression of iNOS and NF- κ B in both non-sensitized and sensitized mice (Fig. 3 a, b ), which could be considered a possible mechanism for the Cr-induced asthmatic phenotype."

The increase in iNOS may have something to do with creatine's effect on arginine metabolism, though in macrophages, it looks like creatine reduces iNOS (?) :

Creatine shapes macrophage polarization by reprogramming L-arginine metabolism [2019] - https://www.jimmunol.org/content/202/1_Supplement/58.5

"Macrophage polarization is accompanied by drastic changes of L-arginine metabolism. Two L-arginine catalytic enzymes, iNOS and arginase 1, are well-characterized hallmark molecules of M(IFN-γ) and M(IL-4) polarization, respectively. The third metabolic fate of L-arginine is generation of creatine that acts as a key source of cellular energy reserve, whereas little is known about regulation and function of creatine metabolism in the immune system. Here, combination of genetic, genomic, metabolic, and immunological analyses revealed that creatine fundamentally reprogrammed macrophage polarization by suppressing M(IFN-γ) yet promoting M(IL-4) effector functions. Mechanistically, creatine inhibited IFN-γ-JAK-STAT1-mediated induction of immune effector molecules including iNOS while supported IL-4-triggered STAT6-dependent upregulation of arginase 1. Depletion of intracellular creatine by ablation of creatine transporter Slc6a8 significantly altered macrophage-mediated immune responses in vivo. These results depicted a previously uncharacterized regulatory loop whereby creatine, a single cellular metabolite, shaped macrophage polarization by regulating L-arginine metabolic enzymes."

I have also noticed it increases allergy symptoms - I could find no publications on this, however.

Consuming lots of shirataki noodles also seems to increase my allergy symptoms. Shirataki noodles are made of konjac flour which is mostly glucomannan. Glucomannan has a skin firming effect (and I note that creatine does also, though the mechanism may be different) since it increases hyaluronic acid production and is also thought to be longevity-promoting. 

 

However, a mouse study found glucomannan reduced allergic rhinitis:

Dietary Pulverized Konjac Glucomannan Prevents the Development of Allergic Rhinitis-Like Symptoms and IgE Response in Mice [2007] - https://pubmed.ncbi.nlm.nih.gov/17928709

It is hard to say if this is a difference between mice and humans generally, or just between mice and me. It's possible the packaged noodles had accumulated a lot of histamine and that is what exacerbated my symptoms.