Standard sugars cause dangerous blood glucose spikes, but for many in our community, standard sugar-free alternatives are off the table because of Mast Cell Activation Syndrome (MCAS).
Many common artificial sweeteners (like aspartame, sucralose, and saccharin), and even certain sugar alcohols (like erythritol or xylitol), can trigger mast cell degranulation. They can spark systemic inflammation, brain fog, digestive distress, and skin flares [1].
Fortunately, a fascinating molecule pulls triple duty: L-glycine.

Metabolically speaking, glycine isn’t a sugar or an artificial sweetener—it is a functional amino acid (a protein building block). It tricks your tongue into tasting sweetness by binding to your mouth’s sweet flavor receptors and sending a “sweet” signal to your brain with zero actual sugar or synthetic chemicals [2].
People often dismiss glycine as just a sleep aid or simple sweetener. In reality, it is a key amino acid that supports tissue repair, immune stability, blood sugar control, and nervous system balance.
For people navigating hypermobile Ehlers-Danlos Syndrome (hEDS), Chiari Malformation, Craniocervical Instability (CCI), MCAS, or dysautonomia, glycine offers targeted benefits far beyond replacing sugar.
1. The Mast Cell Side: A Stabilizer-Friendly Option
- Bypasses Artificial Triggers: Because pure L-glycine is a natural amino acid already native to the human body, it doesn’t trigger the chemical-induced mast cell flares common with synthetic sweeteners [1].
- Calming to the Nervous System: Glycine acts as an inhibitory neurotransmitter in the central nervous system. By helping calm an overactive sympathetic nervous system (fight-or-flight), it can indirectly lower the systemic stress response that often drives mast cell reactivity [3, 4].
- Soothing to the Digestive Tract: Many artificial options feed gut dysbiosis or irritate a sensitive GI tract. Glycine is rapidly absorbed via specific amino acid transporters in the upper small intestine, so it won’t ferment in the gut or cause bloating. Instead, it actively helps protect and repair the fragile intestinal mucosal barrier [5].
2. The Structural Side: Supporting the hEDS Collagen Matrix
- The Premier Collagen Building Block: Collagen is structurally made up of a repeating chain of amino acids (
Glycine - X - Y), and glycine makes up roughly one-third (33%) of that entire matrix [6]. In hEDS, genetic mutations make connective tissue inherently fragile, leading to chronic wear and tear that requires constant cellular turnover [7]. While supplemental glycine cannot alter these underlying genetic mutations, ensuring adequate amino acid availability matters because standard human metabolism naturally falls short of the massive daily demands of baseline collagen synthesis [8].
- Protecting Tissues from Glycation: High blood sugar causes sugar molecules to bond to proteins in a destructive process called glycation, creating Advanced Glycation End-products (AGEs). This process stiffens collagen and makes it brittle—a double hit to tissue integrity for an hEDS patient. Glycine acts as a shield, helping to protect fragile connective tissues from this sugar-driven erosion [9].

3. Brainstem & Nervous System Support (Chiari & CCI)
Chiari Malformation and Craniocervical Instability can compress the brainstem and spinal cord, disrupting cerebrospinal fluid (CSF) flow and over-exciting the central nervous system.
- Natural “Brakes” for Pain & Spasms: Glycine is the primary inhibitory (calming) neurotransmitter in the spinal cord and brainstem [3]. When it binds to its receptors (GlyR), it acts as a nerve damper, helping quiet motor hyperexcitability, muscle spasticity, and chronic pain signals [3, 10].
- Autonomic & Vagal Balance: Many Chiari and hEDS patients struggle with dysautonomia (like POTS). Glycine exerts central anti-inflammatory effects and modulates brainstem tone, helping buffer against hyper-adrenergic “fight-or-flight” surges [3, 11].
- Balanced Brain Function: In the brainstem and forebrain, glycine also works alongside glutamate as an NMDA co-agonist, supporting healthy memory and neuroplasticity without driving excitotoxicity [3].
4. Blood Sugar Control & Glutathione Production
Rather than spiking blood sugar, glycine actively helps your body manage glucose and protect against cellular stress.

- Flattens Glucose Spikes: When taken with food, glycine stimulates the gut hormone GLP-1 and triggers insulin release, helping prevent sharp blood sugar spikes after meals [12].
- Builds Glutathione (GSH): Glycine is a required precursor for glutathione—the body’s master antioxidant [12]. Keeping glutathione levels high protects against liver inflammation and systemic oxidative stress [13].
- Protects Tissue Elasticity: Glycine inhibits Advanced Glycation End-products (AGEs), “sticky sugars” that cross-link with collagen and stiffen joints and blood vessels over time [9].
5. The Glutathione Bottleneck: Why Glycine Often Pairs with NAC (GlyNAC)
While glycine is essential for glutathione synthesis, it doesn’t work alone. Glutathione is a tripeptide composed of three amino acids: glycine, glutamate, and cysteine [13].
Because cysteine is typically the hardest precursor for the liver to source, dietary cysteine (most commonly supplemented as N-acetylcysteine, or NAC) acts as the primary rate-limiting step [13].
- The GlyNAC Synergy: Clinical trials demonstrate that combining glycine with NAC (GlyNAC) dramatically boosts intracellular glutathione levels, reduces systemic oxidative stress, and improves mitochondrial energy production better than either amino acid alone [14].
- A Note of Caution for MCAS & Sensitive Stomachs: While GlyNAC is a powerful metabolic tool, NAC contains sulfur and can sometimes trigger histamine release or gastric distress in sensitive MCAS patients.
- Best Practice: Ensure glycine tolerance first before introducing low-dose NAC, and always discuss new amino acid protocols with your healthcare provider.

💡 How to Use It in Your Routine
Pure L-glycine comes as a clean, white powder that dissolves easily in warm liquids. With a gentle, smooth sweetness, it pairs well as a functional sweetener in custom herbal blends—like morning coffee or my personal favorite, Spiced Dandelion Root Tea—to help protect metabolic health, soothe mast cells, and nourish connective tissue.
- Standard Therapeutic Dose: Clinical studies generally look at 3g to 15g per day, divided into smaller doses with meals or before bed [11, 13].
- Sleep Quality: Taking a 3g dose 30–60 minutes before bed helps lower core body temperature via peripheral vasodilation, promoting deeper slow-wave sleep [14].
- Avoid Stomach Upset: High single doses (> 10 g at once) can pull water into the bowel, causing loose stools or cramping in people with slow GI motility.
- Tip: Start with a low dose (1-2 g per meal) and slowly work your way up to see what your body tolerates best.
References
- Afrin, Lawrence B., et al. “Some Cases of Hypermobile Ehlers–Danlos Syndrome May Be Rooted in Mast Cell Activation Syndrome.” American Journal of Medical Genetics Part C: Seminars in Medical Genetics, vol. 175, no. 1, Mar. 2017, pp. 48–69, doi:10.1002/ajmg.c.31944. onlinelibrary.wiley.com/doi/abs/10.1002/ajmg.c.31944.
- Schmidt, Robert W., and Meghan L. Thompson. “Glycinergic Signaling in the Human Nervous System: An Overview of Therapeutic Drug Targets and Clinical Effects.” Mental Health Clinician, vol. 6, no. 6, Nov. 2016, pp. 266–76, doi:10.9740/mhc.2016.11.266. PubMed Central, pmc.ncbi.nlm.nih.gov/articles/PMC6007534/.
- Li, Xiangli, et al. “Dietary Glycine Prevents Peptidoglycan Polysaccharide-Induced Reactive Arthritis in the Rat: Role for Glycine-Gated Chloride Channel.” Infection and Immunity, vol. 69, no. 9, Sept. 2001, pp. 5883–91, doi:10.1128/IAI.69.9.5883-5891.2001. PubMed Central, pmc.ncbi.nlm.nih.gov/articles/PMC98707/.
- Howard, Alison, et al. “Glycine Transporter GLYT1 Is Essential for Glycine-Mediated Protection of Human Intestinal Epithelial Cells Against Oxidative Damage.” The Journal of Physiology, vol. 588, no. 6, Mar. 2010, pp. 995–1009, doi:10.1113/jphysiol.2009.186262. physoc.onlinelibrary.wiley.com/doi/full/10.1113/jphysiol.2009.186262.
- Shoulders, Matthew D., and Ronald T. Raines. “Collagen Structure and Stability.” Annual Review of Biochemistry, vol. 78, no. 1, June 2009, pp. 929–58, doi:10.1146/annurev.biochem.77.032207.120833. PubMed Central, pmc.ncbi.nlm.nih.gov/articles/PMC2846778/.
- Tinkle, Brad, et al. “Hypermobile Ehlers–Danlos Syndrome (a.k.a. Ehlers–Danlos Syndrome Type III and Joint Hypermobility Syndrome): Clinical Description and Natural History.” American Journal of Medical Genetics Part C: Seminars in Medical Genetics, vol. 175, no. 1, Mar. 2017, pp. 48–69, doi:10.1002/ajmg.c.31538. onlinelibrary.wiley.com/doi/10.1002/ajmg.c.31538.
- Meléndez-Hevia, Enrique, et al. “A Weak Link in Metabolism: The Metabolic Capacity for Glycine Biosynthesis Does Not Satisfy the Need for Collagen Synthesis.” Journal of Biosciences, vol. 34, no. 6, Dec. 2009, pp. 853–72, doi:10.1007/s12038-009-0100-9. Indian Academy of Sciences, www.ias.ac.in/article/fulltext/jbsc/034/06/0853-0872.
- Wang, Xuan, et al. “Glycine Suppresses AGE/RAGE Signaling Pathway and Subsequent Oxidative Stress by Restoring Glo1 Function in the Aorta of Diabetic Rats and in HUVECs.” The Journal of Nutritional Biochemistry, vol. 70, Aug. 2019, pp. 16–25, doi:10.1016/j.jnutbio.2019.03.018. PubMed, pubmed.ncbi.nlm.nih.gov/30944692/.
- Gundersen, Rune Y., Pål S. Opstad, and Frode Fonnum. “Glycine – An Important Neurotransmitter and Cytoprotective Agent.” Acta Anaesthesiologica Scandinavica, vol. 49, no. 8, Sept. 2005, pp. 1108–16, doi:10.1111/j.1399-6576.2005.00786.x. onlinelibrary.wiley.com/doi/abs/10.1111/j.1399-6576.2005.00786.x.
- Zafra, Francisco, et al. “Glycine Transporters and Its Coupling with NMDA Receptors.” Advances in Neurobiology, vol. 16, no. 1, Meeting 2017, pp. 55–83, doi:10.1007/978-3-319-55769-4_4. PubMed, pubmed.ncbi.nlm.nih.gov/28828606/.
- McCarty, Mark F., and James J. DiNicolantonio. “The Cardiometabolic Benefits of Glycine: Is Glycine an ‘Antidote’ to Dietary Fructose?” Open Heart, vol. 1, no. 1, May 2014, pp. 1–9, doi:10.1136/openhrt-2014-000103. PubMed Central, pmc.ncbi.nlm.nih.gov/articles/PMC4195924/.
- Sekhar, Rajagopal V., et al. “Glutathione Synthesis Is Diminished in Patients with Uncontrolled Diabetes and Restored by Dietary Supplementation with Cysteine and Glycine.” Diabetes Care, vol. 34, no. 1, Jan. 2011, pp. 162–67, doi:10.2337/dc10-1006. PubMed Central, pmc.ncbi.nlm.nih.gov/articles/PMC3005481/.
- Kumar, Premranjan, et al. “Supplementing Glycine and N-Acetylcysteine (GlyNAC) in Older Adults Improves Glutathione Deficiency, Oxidative Stress, Mitochondrial Dysfunction, Inflammation, Physical Function, and Aging Hallmarks: A Randomized Clinical Trial.” The Journals of Gerontology: Series A, vol. 78, no. 1, Jan. 2023, pp. 75–89, doi:10.1093/gerona/glac135. https://academic.oup.com/biomedgerontology/article/78/1/75/6668639.
- Yamadera, Wataru, et al. “Glycine Ingestion Improves Subjective Sleep Quality in Human Volunteers, Correlating with Polysomnographic Changes.” Sleep and Biological Rhythms, vol. 5, no. 2, Apr. 2007, pp. 126–31, doi:10.1111/j.1479-8425.2007.00262.x. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1479-8425.2007.00262.


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