My Icelandic reader also praised the impact of Zinc carnosine on his gut.
“1) I believe Zinc Carnosine is of importance for treating Leaky Gut. I had constant nausea for months after using for a while and quiting the medicine Plaquenil and Kratom. I think it caused increased permeability of the gut (don´t know which one was the cause – or both). I experienced increase wellbeing and relaxation after 3 weeks on Zinc Carnosine. Nausea completely went away and hasn´t been back.It has been used in Japan for abt. two decades now I believe. Somewhere I saw it was researched by making it radioactive and pictures showed it accumulate at the gut lining. The Carnosine is a big molecule that slows the absorption of the Zinc so it does it´s healing at the gut lining.”
As always, it’s to PubMed to see if there is solid evidence supporting his exceptional experience
Zinc carnosine is also the main component of polaprezinc.
- Zinc carnosine works with bovine colostrum in truncating heavy exercise-induced increase in gut permeability in healthy volunteers.
- Zinc carnosine, a health food supplement that stabilises small bowel integrity and stimulates gut repair processes .
- “A zinc-carnosine chelate compound, PZ, enema may become a useful new add-on treatment to accelerate mucosal healing in UC.” 
- Polaprezinc, a mucosal protective agent, in combination with lansoprazole, amoxycillin and clarithromycin increases the cure rate of Helicobacter pylori infection.
So the evidence supports his experience. What about impact on the microbiome? There was nothing explicit for this, so I will fall back to the impact of zinc.
“Zinc is an essential trace element required for multiple cellular functions, such as enzymatic reactions, DNA synthesis, and gene expression (1). Over 300 enzymes and thousands of transcription factors contain one or more zinc atoms.” 
- “In the zinc-deficient chickens, the bacterial profiles were less diverse, leading to reduced bacterial activity. Gut bacteria are important for a number of reasons, including breaking down nutrients in food into short-chain fatty acids, which increases gut acidity and contributes to digestion and the solubility of minerals, particularly iron and zinc.” 
- “Bacterial community composition was altered in the Zn deficient group, where significantly greater abundance of Proteobacteria and significantly lower abundance of Firmicutes (Figure 3A) was observed. In the Zn(−) group, the abundance of Bacteroidetes was increased whereas Actinobacteria was diminished, albeit not significantly.”
- ” In contrast, in the stool samples there was a higher relative abundance of Bacteroidetes and lower abundance of Firmicutesobserved in ME/CFS patients compared to healthy controls.”  – same pattern as a Zinc Deficient microbiome.
- “Serum levels of zinc (P = 0.001) and magnesium (P = 0.002) were significantly decreased by FM groups, ….Association between serum zinc level and number of tender points (P = 0.008)” 
- Zinc Deficiency is Associated with Poor Clinical Outcomes in Patients with Inflammatory BowelDisease .
- “Serum levels of zinc, SOD activity, albumin, and total protein were significantly lower (P < 0.05) in IBD patients than controls”,
- Iron Deficiency, Zinc, Magnesium, Vitamin Deficiencies in Crohn’s Disease: Substitute or Not?
- In chronic fatigue syndrome, the decreased levels of omega-3 poly-unsaturated fatty acids are related to lowered serum zinc and defects in T cell activation .
- Lower serum zinc in Chronic Fatigue Syndrome (CFS): relationships to immune dysfunctions and relevance for the oxidative stress status in CFS .
Just as with molybdenum in my last post, supplementation can reasonably be expected to shift the microbiome away from the usual pattern seen with CFS patients. I could not find suitable comparison between different forms of zinc supplementation.
For dosage: 30-40 mg/day see this post