histidine, skin, circulating ammonia - brief notes

Notes on:

Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement  (2020)

https://www.mdpi.com/2072-6643/12/3/848

"According to several studies, dietary [histidine] HIS affects histamine concentrations in immune cells, the stomach, and the brain [58,59,60,61]. Altered function of the immune system, allergic reactions, and/or peptic ulcers have not been reported after HIS administration.
...

In the skin, filaggrin, a skin barrier protein with high HIS content, is the main HIS source for histidase to generate ammonia and urocanate [40]. Because most of the ammonia produced in the splanchnic region is detoxified to urea in the liver, the skin should be considered a significant source of blood ammonia in the systemic circulation.

...

Although HIS is a precursor of histamine, allergic reactions or peptic ulcers caused by increased gastric acid secretion have not been reported. Practically important might be reduced folate status [45,46,126], anorexia [62,63,64,65,66,67,68,69], and increased loss of zinc in urine reported after HIS administration in overweight subjects and patients with progressive systemic sclerosis [135,136]. Several metabolic alterations noted below indicate that increased HIS consumption is inappropriate in subjects with liver injury."

- HIS has anorectic (appetite suppression) effect

- reduces anxiety like behaviors in mice

- bonito broth consumption, high in HIS, improves cognitive function - though it also contains other potentially active constituents

- HIS prevents aspirin-induced gastric mucosal damage 

- increases filaggrin and reduces eczema / atopic dermatitis

Very interesting that histidine is a histamine precursor yet seems to reduce some effects of excessive histamine release (e.g. anxiety, allergic reactions).

[update: I tried histidine as a supplement and had problems with heartburn. Oral histamine increases stomach acid production in some dogs, but not others: https://pubmed.ncbi.nlm.nih.gov/9123915/]

Histidine, lysine, and threonine were found to stabilize mast cells and inhibit mTOR signalling in mast cells:

Dietary interventions that reduce mTOR activity rescue autistic-like behavioral deficits in mice (2017) https://doi.org/10.1016/j.bbi.2016.09.016

~

Does oral histidine intake increase erothioneine production by gut microbiota?

 

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