Bone Broth for Sleep and Glycine

Bone broth is the most glycine-rich food in the human diet by a substantial margin — a single cup of well-made broth delivers approximately 1-2 g of free and gelatin-derived glycine. That is half to two-thirds of the 3 g dose used in the Bannai sleep-architecture trials at Ajinomoto Pharmaceutical, which established that 3 g of glycine taken approximately one hour before bed reduces sleep latency, increases slow-wave (deep) sleep, improves subjective sleep quality, and reduces next-day fatigue in patients with insomnia and in healthy volunteers with sleep complaints. The mechanism appears to involve glycine's action at central N-methyl-D-aspartate (NMDA) receptors (where it is a required co-agonist) and at the suprachiasmatic nucleus (where it modestly lowers core body temperature, an essential signal for sleep onset). This page covers the glycine-sleep evidence base, the "cup before bed" bone broth protocol, the comparison to powdered glycine and to other sleep aids, and the broader case for nightly glycine intake as a low-cost intervention with multiple downstream benefits.

Table of Contents

1. How Much Glycine Is in a Cup of Broth
2. Glycine's Pharmacology — NMDA Co-Agonist and Inhibitory Neurotransmitter
3. The Bannai / Ajinomoto Sleep Trials
4. Core Body Temperature and Sleep Onset
5. Sleep Architecture — Slow-Wave vs REM
6. The "Cup Before Bed" Protocol
7. Bone Broth vs Powdered Glycine for Sleep
8. Glycine vs Other Sleep Aids (Melatonin, Magnesium, L-Theanine)
9. Downstream Benefits Beyond Sleep
10. Cautions and Drug Interactions
11. Key Research Papers
12. Connections

How Much Glycine Is in a Cup of Broth

Gelatin — the protein matrix extracted from bones during a long simmer — is approximately 33% glycine by amino-acid composition, which is the highest glycine content of any common dietary protein source. For comparison: beef muscle protein is roughly 6% glycine, casein in milk is 2%, whey is 1.7%, and egg white is 4%. Gelatin's glycine content is several-fold higher than any other dietary protein.

A well-made cup of bone broth that gels firmly when chilled contains approximately 9-15 g of total protein, almost all of which is gelatin. At 33% glycine composition, this works out to approximately 3-5 g of glycine per cup — though this figure represents total glycine bound in the gelatin matrix, not free glycine immediately bioavailable. The fraction that is in free form (already hydrolyzed during the long simmer) is smaller, on the order of 0.5-1 g per cup. The remainder is released as the body digests the gelatin over the following hours.

For the sleep application, the key question is how much glycine arrives in the bloodstream within the 30-60 minute window before bedtime when serum glycine elevation would be expected to influence sleep onset. Free glycine in the broth reaches peak serum concentration in 30-60 minutes. Glycine released from gelatin digestion arrives more gradually over 1-4 hours. The combined kinetics deliver a meaningful glycine bolus over the typical sleep window.

The published Bannai sleep trials used 3 g of free glycine in water as the test dose. A cup of bone broth delivers roughly 0.5-1 g of free glycine and several additional grams over the digestion window — so the kinetics are different from the supplement, but the total glycine load reaching the brain over the course of the night is in the same range. Anecdotally, patients on the WAPF / nourishing-traditions "cup of broth before bed" protocol consistently report sleep improvement comparable to powdered glycine.

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Glycine's Pharmacology — NMDA Co-Agonist and Inhibitory Neurotransmitter

Glycine is unusual among amino acids in having direct, well-characterized neurotransmitter activity. It operates through two distinct receptor systems with opposite effects:

• Inhibitory glycine receptors — ligand-gated chloride channels expressed in the brainstem and spinal cord. Glycine binding opens the channel, allowing chloride influx, which hyperpolarizes the neuron and inhibits its firing. This is glycine's "Valium-like" inhibitory effect — the same mechanism by which strychnine causes lethal convulsions (strychnine blocks the glycine receptor, leaving brainstem motor neurons unopposed in their firing). The inhibitory glycine receptor is concentrated in motor control circuits and contributes to the modest muscle-relaxant effect of glycine.
• NMDA receptor co-agonist site — the N-methyl-D-aspartate glutamate receptor requires both glutamate and a co-agonist (glycine or D-serine) for full activation. Glycine binds at the "glycine site" on the NMDA receptor and modulates its function. The NMDA receptor is the principal substrate for synaptic plasticity (long-term potentiation, the cellular basis of memory) and is the target of psychiatric drugs including ketamine, memantine, and PCP. Glycine's role at this site is more complex than the brainstem inhibitory effect — it is a permissive modulator rather than a direct agonist or antagonist.

For the sleep application specifically, the relevant mechanism appears to be a combination of:

1. Modest brainstem inhibition — reduced sensory and motor drive, helping the transition to sleep
2. Suprachiasmatic nucleus (SCN) effects — lowering of core body temperature, which is an essential sleep-onset signal (see below)
3. NMDA modulation in cortical circuits — possibly contributing to slow-wave sleep enhancement
4. Reduction of sympathetic nervous system tone — small reduction in heart rate and blood pressure during the hour after dosing

The combined effect is a gentle "lights down" signal to the central nervous system without the strong receptor agonism that produces the cognitive impairment, dependence, and rebound insomnia of benzodiazepines and z-drugs (zolpidem, eszopiclone). Glycine is essentially the inverse of these drugs — weak effect, no addictive potential, no morning grogginess, no dependency.

For deeper treatment of glycine biochemistry — including its roles in methylation, glutathione synthesis, and aspirin detoxification — see our Glycine page.

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The Bannai / Ajinomoto Sleep Trials

The systematic clinical investigation of glycine for sleep was led by Makoto Bannai and Nobuhiro Kawai at Ajinomoto Pharmaceuticals in Japan, beginning in the mid-2000s. Ajinomoto, founded in 1909 around the commercialization of monosodium glutamate, is one of the world's largest producers of food-grade amino acids, and the company has invested heavily in clinical research on amino acid therapeutics. The glycine sleep program produced a series of placebo-controlled trials that established the basic dosing and efficacy:

• Yamadera et al. 2007 (Sleep and Biological Rhythms) — the first formal trial. Adults with chronic sleep complaints (subjective insomnia) received 3 g of glycine in water vs placebo about 1 hour before bedtime. The glycine group showed reduced sleep latency (faster sleep onset), improved subjective sleep quality on the Pittsburgh Sleep Quality Index components, and reduced next-day fatigue.
• Inagawa et al. 2006 (Sleep and Biological Rhythms) — followed up on subjective effects with polysomnographic measurement. Showed objective improvement in sleep efficiency, faster appearance of slow-wave sleep, and reduced wakefulness after sleep onset.
• Bannai & Kawai 2012 (Journal of Pharmacological Sciences) — the consolidated review of the program. Confirmed the 3 g dose, the approximately 60-minute pre-bed timing, the safety profile, and the mechanism hypothesis involving core body temperature reduction.
• Bannai et al. 2012 (Frontiers in Neurology) — tested glycine in healthy volunteers under sleep restriction (forced reduction to 25% less sleep than usual for 3 nights), measuring next-day cognitive performance. The glycine group showed less impairment of psychomotor vigilance and recognition memory than placebo — suggesting that glycine's benefit extends beyond just subjective sleep quality to objective protection of cognitive function under sleep deprivation stress.
• Kawai et al. 2015 (Neuropsychopharmacology) — investigated the mechanism using rat models, demonstrating that glycine's sleep-promoting effect involves the suprachiasmatic nucleus and NMDA receptor-mediated lowering of core body temperature. Antagonism of the NMDA receptor blocked glycine's sleep effect, supporting NMDA modulation as a key mechanism.

The trial data are consistent: 3 g of glycine taken approximately 1 hour before bed produces measurable sleep-architecture improvements that translate to subjective benefit and to next-day cognitive protection, with no significant adverse effects. Effect size is modest but consistent — not transformative for severe insomnia, but a reasonable mild sleep aid for the much larger population of patients with subclinical sleep complaints, jet lag, shift work, or stress-related sleep disruption.

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Core Body Temperature and Sleep Onset

The body's core temperature follows a clear circadian rhythm, peaking in late afternoon and reaching its nadir approximately 2 hours after sleep onset. The transition from waking to sleep is preceded by an active drop in core temperature of 0.5-1.0°C, driven by peripheral vasodilation (the warm hands and feet that often precede sleep onset) that dissipates body heat. This temperature drop is not just a correlate of sleep onset — it appears to be a causally required signal. Interventions that prevent the temperature drop (warm room, electric blanket, heated room) delay sleep onset; interventions that accelerate it (warm bath 1-2 hours before bed, which causes initial vasoconstriction followed by rebound vasodilation) accelerate sleep onset.

The Bannai team's mechanistic investigation found that 3 g of oral glycine produces a modest reduction in core body temperature — approximately 0.3-0.5°C — that is detectable within 30-60 minutes of dosing and persists for several hours. The proposed mechanism is glycine's effect on the suprachiasmatic nucleus, the brain's master circadian pacemaker, which modulates the autonomic nervous system signals controlling peripheral vasodilation. By lowering core temperature, glycine produces or enhances the signal that the body interprets as "time for sleep."

This mechanism is shared with several other modest sleep interventions:

• Warm bath 1-2 hours before bed — produces the temperature drop via rebound vasodilation after initial warming
• Cool bedroom (65-68°F / 18-20°C) — supports the natural temperature drop by removing the environmental heat barrier
• Avoidance of evening exercise — exercise raises core temperature and can delay the evening cooling phase by 1-2 hours if done too late
• Melatonin — produces a modest peripheral vasodilation that enhances the temperature drop
• Glycine 3 g pre-bed — produces a similar modest temperature drop via SCN-mediated peripheral vasodilation

Combining glycine with the environmental temperature interventions (cool bedroom, no late workout, optional warm bath 90 minutes pre-bed) appears to produce additive effects greater than glycine alone — an important practical point for patients trying to optimize sleep without pharmaceutical intervention.

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Sleep Architecture — Slow-Wave vs REM

Polysomnographic measurement of sleep distinguishes several distinct sleep stages, each with characteristic EEG patterns and physiologic correlates:

• N1 (light sleep) — transition phase, easily disrupted, 5-10% of total sleep
• N2 (intermediate sleep) — the largest sleep stage, 45-55% of total sleep, characterized by sleep spindles and K-complexes
• N3 (slow-wave / deep sleep) — the most physiologically restorative stage, 15-25% of total sleep in young adults declining to 5-10% in older adults, characterized by high-amplitude delta-wave EEG activity. This is the sleep stage during which growth hormone secretion peaks, glymphatic clearance of brain metabolic waste is most active, and memory consolidation occurs.
• REM (rapid eye movement / dream sleep) — 20-25% of total sleep, characterized by skeletal muscle atonia and intense brain activity. The principal stage for emotional processing and procedural memory consolidation.

The Bannai polysomnographic data showed that 3 g of pre-bed glycine specifically increases the proportion of slow-wave (N3) sleep without significantly disrupting REM. This is an important distinction because most sleep aids — benzodiazepines, z-drugs, alcohol, sedating antihistamines — suppress both slow-wave and REM sleep. The user feels more deeply asleep (because of the receptor sedation) but the actual restorative sleep architecture is degraded. Morning grogginess, "hangover" effect, and impaired memory consolidation are downstream consequences.

Glycine's preservation of slow-wave sleep without REM suppression is its key advantage as a sleep aid. The patient experiences improved subjective sleep quality, increased slow-wave sleep on objective measurement, and improved next-day cognitive performance — without the architecture distortion that comes with pharmaceutical sedation. The trade-off is that the magnitude of subjective effect is modest. For severe insomnia, glycine alone is insufficient; for the much larger population of patients with mild-to-moderate sleep complaints, it is often enough.

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The "Cup Before Bed" Protocol

The WAPF / nourishing-traditions practitioner community has converged on a "cup of warm bone broth approximately 60-90 minutes before bed" protocol as the practical translation of the glycine-for-sleep literature. The protocol is:

1. Warm 1 cup of well-made (gelling) bone broth in a saucepan or microwave to drinking temperature (about 140-160°F / 60-70°C, hot enough to be soothing but not scalding)
2. Drink slowly over 5-10 minutes, ideally seated in a relaxed setting (not standing at the kitchen counter)
3. Allow 60-90 minutes before getting into bed for the glycine bolus to begin influencing core body temperature and the broader sleep onset signal
4. Combine with other sleep hygiene measures (cool bedroom, dim lights, no screens for the hour before bed) for additive effect
5. Use nightly, not just occasionally — the effect appears to build over the first 1-2 weeks of consistent use, similar to other gentle sleep aids

Patient feedback on this protocol is consistently positive among those who tolerate the broth flavor and have access to well-made broth. The warm-liquid ritual itself has a sleep-inducing effect independent of the glycine content (similar to the bedtime cup of chamomile tea or warm milk traditions), and the slow drinking pace creates a natural slowdown that aids the transition to sleep.

For patients who do not want to drink savory broth before bed, alternative formats that deliver similar glycine load include:

• 3 g of powdered L-glycine dissolved in warm water with a small amount of stevia or honey for palatability — this is the supplement version of the Bannai trial dose
• 1 cup of warm milk with 1 scoop (10 g) of collagen peptides stirred in — delivers roughly 3 g of glycine plus other gelatin amino acids in a sweet rather than savory format
• "Bone broth + collagen peptide" combination — a half cup of broth plus a half scoop of collagen peptides, for those who tolerate some broth but want supplementary glycine

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Bone Broth vs Powdered Glycine for Sleep

For the specific outcome of pre-bed glycine dosing for sleep, powdered L-glycine has several advantages:

• Dose precision — a precisely measured 3 g (one teaspoon of L-glycine powder) matches the Bannai trial dose exactly; broth varies batch to batch
• Convenience — powder dissolves in any liquid; broth requires heating and a willingness to drink savory liquid before bed
• Cost — pharmaceutical-grade L-glycine powder costs approximately $0.05 per 3 g dose; bone broth costs $1-2 per cup homemade or $5-8 per cup commercial
• Travel and shelf stability — powder lasts years and travels anywhere
• Histamine-free — relevant for the MCAS / POTS / SIBO population, for whom broth's histamine content can be a sleep disruptor
• Sweet rather than savory taste profile — L-glycine has a mildly sweet taste (it is one of the few sweet amino acids), pleasant in warm water with a little honey

Broth has its own advantages in the sleep context:

• Whole-food matrix — the additional amino acids, modest minerals, and small amount of fat (if not skimmed) in broth produce a more complex pre-bed nutritional input than isolated glycine
• Ritual — the warm-cup-before-bed ritual is itself sleep-promoting independent of the glycine content
• Combined with caloric value — for patients who tend to wake hungry, a cup of broth is a small "before bed snack" that quiets the appetite without the blood-sugar disruption of carbohydrate-heavy snacks
• Integration with broader gut-healing / nourishing-traditions practice — if the patient is already drinking broth daily for gut healing or convalescence, the bedtime cup is just a continuation of an existing practice rather than a new intervention

The practical recommendation: try both, see which the patient prefers, and use what they will actually use consistently. Many patients land on powder for travel and weeknights, broth for weekends or when the broth is fresh.

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Glycine vs Other Sleep Aids (Melatonin, Magnesium, L-Theanine)

Glycine is one of several "gentle" sleep aids that occupy the space between basic sleep hygiene and pharmaceutical hypnotics. Each has a distinct mechanism, evidence profile, and ideal patient population:

• Melatonin (0.3-3 mg, taken 30-60 min before bed) — the strongest evidence base of the gentle interventions. Works principally on circadian timing rather than sleep depth, so most effective for jet lag, shift work, delayed sleep phase syndrome, and elderly patients with declining endogenous melatonin. Lower doses (0.3-0.5 mg) appear to be more physiological and often more effective than the 3-5 mg doses commonly sold; megadose melatonin (10+ mg) is increasingly common in supplement stores but has weaker evidence and more next-day grogginess.
• Magnesium glycinate (200-400 mg before bed) — the magnesium component supports relaxation via NMDA modulation, GABA support, and muscle relaxation; the glycine component contributes the sleep effects discussed on this page. Magnesium glycinate is the "two-for-one" approach to gentle sleep aid that targets multiple mechanisms in one supplement. See our Magnesium page.
• L-theanine (100-400 mg, often combined with magnesium) — the amino acid abundant in green tea. Increases alpha brain waves, promotes calm wakefulness during the day and gentler transition to sleep at night. Particularly useful for patients whose sleep onset difficulty is driven by ruminative anxiety.
• Apigenin (50 mg from chamomile or as isolated supplement) — flavonoid in chamomile that binds GABA receptors with modest sedative effect. Used in some popular sleep stacks including the Andrew Huberman protocol.
• Glycine (3 g pre-bed) — the focus of this page. Best for patients whose primary issue is sleep depth (frequent awakenings, light sleep, poor next-day recovery) rather than initial sleep onset latency. Often combined with melatonin for patients with both onset and maintenance issues.

A common "stack" used by sleep-optimization practitioners: 0.5 mg melatonin + 200 mg magnesium glycinate + 100 mg apigenin + 3 g glycine, all 60-90 minutes before bed. Each component has modest individual effect; the combination targets multiple mechanisms (circadian timing, GABA, NMDA, core temperature) and often produces meaningful additive benefit.

Pharmaceutical hypnotics (zolpidem, eszopiclone, suvorexant, trazodone) remain appropriate for severe established insomnia or for time-limited intervention during acute stressors. The gentle interventions discussed here are not replacements for these drugs in their proper indications — they are the right first-line for the much larger population of patients with mild-to-moderate sleep complaints who do not need or want pharmaceutical intervention.

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Downstream Benefits Beyond Sleep

One of the appealing features of nightly glycine intake (whether from broth or supplement) is that the same glycine bolus has multiple downstream effects beyond sleep:

• Methylation buffer — glycine N-methyltransferase (GNMT) is one of the body's major buffers against excess methylation. Patients on high-methyl-donor regimens (B12 + methylfolate for MTHFR polymorphisms, SAM-e for depression, betaine for homocysteine) can develop "methyl trapping" anxiety symptoms. 3 g of glycine acts as a methyl acceptor and can blunt these effects. See our Glycine and Aspirin Metabolism page for related discussion.
• Glutathione synthesis substrate — glycine is one of the three amino acids in glutathione (glutamate + cysteine + glycine). Glutathione synthesis is often glycine-limited rather than cysteine-limited in patients on long-term NAC supplementation. Adequate glycine supports the full glutathione cycle.
• Bile acid conjugation — the liver conjugates bile acids to glycocholate and glycochenodeoxycholate using glycine. Adequate glycine supports the enterohepatic bile circulation that recycles 95% of bile acids each day.
• Collagen synthesis — glycine occupies every third position in the collagen triple helix. Repleting glycine supports the collagen-related effects discussed on the Joints and Collagen page.
• Insulin sensitivity — some evidence suggests that glycine supports insulin sensitivity through effects on the glycine receptor in pancreatic beta cells and through methylation buffering. Several small trials have tested glycine as adjunct in type 2 diabetes management.
• Aspirin metabolism — the liver clears salicylate by conjugation to salicyluric acid, which uses glycine. Patients on chronic low-dose aspirin can become glycine-depleted; nightly glycine supports this detoxification pathway. See Glycine and Aspirin Metabolism.
• Anti-inflammatory effect via glycine-gated chloride channels — macrophages, T cells, and Kupffer cells express glycine receptors; glycine binding modestly suppresses pro-inflammatory cytokine output

The multi-pathway benefit profile is part of what makes nightly glycine such a low-risk high-leverage intervention. A patient drinking a cup of bone broth before bed for sleep gets these additional benefits at no additional cost. For patients using powdered glycine, the same applies.

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Cautions and Drug Interactions

Glycine has a near-perfect safety profile, but a few considerations:

• Clozapine — glycine can potentiate clozapine's NMDA-modulating effects. Patients on clozapine should consult their psychiatrist before adding glycine.
• Ketamine therapy — for patients undergoing low-dose ketamine therapy for depression or chronic pain, glycine may modify NMDA receptor function and alter the ketamine response. Discuss with the prescribing clinician.
• Anticonvulsants — theoretical interaction at the inhibitory glycine receptor; not commonly reported as clinically meaningful
• Schizophrenia spectrum disorders — some clinical trials have used 30-60 g/day of glycine as adjunct in schizophrenia. The data on whether this helps or hinders is mixed. Routine 3 g/day for sleep is unlikely to have significant effect on psychotic-spectrum illness, but discuss with treating psychiatrist.
• Bone broth specific — histamine intolerance — the histamine content of long-simmered broth can disrupt sleep in MCAS / SIBO / POTS patients who are histamine-reactive. Use short-simmer broth (4-6 hours), pressure-cooker broth (2-3 hours), or switch to powdered glycine to bypass the histamine load.
• Sodium load — for patients on sodium restriction (heart failure, advanced CKD), salted commercial broth may contribute too much sodium for nightly use; unsalted homemade broth or powdered glycine are alternatives.
• Diabetic patients — broth contributes minimal carbohydrate but does have some calorie load; powdered glycine is essentially zero calorie. Both are compatible with most diabetic dietary approaches.
• Pregnancy and lactation — bone broth is a traditional postpartum food across cultures and is safe and beneficial in pregnancy. Powdered glycine has not been systematically tested in pregnancy at the 3 g dose; the same amount from broth would be expected to be equivalent and is generally considered safe.

The overall risk profile is essentially benign — nightly glycine is one of the safest sleep interventions available and has none of the dependency or cognitive-impairment concerns of pharmaceutical sedatives.

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Key Research Papers

1. Bannai M, Kawai N (2012). New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep. Journal of Pharmacological Sciences. — PubMed
2. Yamadera W et al. (2007). Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep and Biological Rhythms. — PubMed
3. Inagawa K et al. (2006). Subjective effects of glycine ingestion before bedtime on sleep quality. Sleep and Biological Rhythms. — PubMed
4. Bannai M et al. (2012). The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Frontiers in Neurology. — PubMed
5. Kawai N et al. (2015). The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus. Neuropsychopharmacology. — PubMed
6. Meléndez-Hevia E et al. (2009). A weak link in metabolism: the metabolic capacity for glycine biosynthesis does not satisfy the need for collagen synthesis. Journal of Biosciences. — PubMed
7. File SE et al. (1999). A study of the effects of glycine on mood and cognition in healthy volunteers. Pharmacology, Biochemistry, and Behavior. — PubMed
8. Kräuchi K, Cajochen C, Wirz-Justice A (2006). Waking up properly: is there a role of thermoregulation in sleep inertia? Journal of Sleep Research. — PubMed
9. Pearson AL, Buenaventura J, Wadhwa P (2017). The role of glycine in modulating peripheral and central inflammation. Inflammation Research. — PubMed
10. Zhong Z et al. (2003). L-glycine: a novel antiinflammatory, immunomodulatory, and cytoprotective agent. Current Opinion in Clinical Nutrition and Metabolic Care. — PubMed
11. Díaz-Flores M et al. (2013). Oral supplementation with glycine reduces oxidative stress in patients with metabolic syndrome. Canadian Journal of Physiology and Pharmacology. — PubMed
12. Razak MA et al. (2017). Multifarious beneficial effect of nonessential amino acid, glycine: a review. Oxidative Medicine and Cellular Longevity. — PubMed

PubMed Topic Searches

• PubMed: Glycine sleep latency
• PubMed: Glycine slow-wave sleep
• PubMed: Core body temperature sleep onset
• PubMed: NMDA glycine suprachiasmatic
• PubMed: Gelatin amino acid glycine

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Connections

• Bone Broth Overview
• Bone Broth Benefits Hub
• Bone Broth for Gut Healing
• Bone Broth for Joints & Collagen
• Bone Broth for Mineral Repletion
• Glycine
• Glycine & Aspirin Metabolism
• Proline
• Glutamine
• Magnesium (Glycinate)
• Collagen
• Gut Healing
• Gut-Brain Axis
• Joint Pain
• All Superfoods

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