I’m not sure if this holds any weight but I’m using NAC specifically to lower my histamine. Although I’ve never been tested, I seem to have histamine intolerance/MCAS. My histamine spikes fairly regularly and NAC has been a lifesaver. It’s quick and effective.
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This is extremely interesting.
I’va had severe insomnia recently on several occasions, often accompanied by itching. It’s finally chatGPT that suggested the culprit was histamine, and indeed, on the worst insomnia nights, I ate a lot of high-histamine foods, and cutting them out stopped the insomnia. Later, my doctor prescribed me an anti-histamine, and while I don’t want to take that long term (it’s more of an experiment), it definitively helps me sleep.
How much Nac do you take to help with histamine?
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I find the same thing for myself. When my histamine is up I tend to have hot flashes which makes it difficult to sleep. I have 600 mg capsules and I take one at a time. If my histamine is just starting to go up, only 1 capsule will nip it. For a severe attack I keep taking capsules until I get relief. There have been a few times that I needed at least 6 capsules over the course of a few hours. That’s rather rare though.
Since we’re talking about difficult sleeping… that’s been an ongoing issue over the past decade for me. I started using sermorelin and at the very beginning it helped. Then the honeymoon was over. After about 2 months of sermorelin I added VIP. I find that I fall asleep faster and stay asleep longer.
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I want to say high gram glycine has a special relationship with tea in the morning…
I used to take it with coffee, where it just acted as a slightly off putting sugar, but man does glycine accentuate a tea bag… brings all the flavor out and sweetens it without any offput
I guess it prevents me from overdoing the coffee, as tea is more measured in the caffeine for maximal health
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This spread sheet is based on some older studies on GlyNAC the name that the Nestle supplement division gave to this combo and trademarked.
Glycine_NAC_dosing_costing_v1.xlsx (31.9 KB)
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You may want to find a cheaper source of NAC. I typically pay $.09 per 600 mg cap or less. I use Bulk Supplements and Nutricost.
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NAC can indirectly calm mast cells, but the quick sleep effect is more likely from its anxiolytic/glutamate action than histamine lowering. For histamine issues, DAO enzyme or quercetin (unless you’ve slow MAOA) would be more on point.
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New study about cysteine (and maybe NAC?):
Dietary cysteine enhances intestinal stemness via CD8+ T cell-derived IL-22
https://www.nature.com/articles/s41586-025-09589-5
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I did that spread sheet 5 years ago and have not undated it since then 
Back on high gram glycine for a few months and my body fat composition not the same…
It’s the only thing in my stack I feel that has this effect. Rapa? Jardiance? Telmisartan 80? The rest of the stack? If I stop the glycine, I gain fat, IMO.
I’m taking a lot of stuff, but I feel its taking the high gram glycine that cuts the fat…
And why? Apparently among its many qualities it may stimulate glp-1 and possibly act as an agonist… How does it compare in this role with the other glp-1 meds?
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