Glycine is a non-essential amino acid which means our bodies are able to make it on their own from other compounds. It serves as an inhibitory neurotransmitter, is a powerful anti-oxidant, and helps support joint health. As it turns out though, research suggests we might not be getting nearly the amount of glycine we need from diet alone!
Glycine is considered a conditionally-essential amino acid which means that, under normal circumstances, our bodies should produce enough on their own. During times of stress such as colds or trauma, our bodies may require additional dietary sources of conditionally-essential amino acids. There are some compelling arguments to suggest that glycine should be considered an essential amino acid, but we’ll get to that later. First, let’s consider the many health benefits of glycine.
Recommended Glycine Supplements
Health Benefits of Glycine
Glycine plays an essential role for a wide range of physiological processes in our bodies. It serves as an intermediary compound in many metabolic processes, helps reduce inflammation, mitigates tissue damage from oxidative stress, and can even help skin wounds heal faster. The number of ways our body can use glycine is truly remarkable. There’s some solid science to support the health benefits offered by glycine and there’s also some science to suggest exciting, newly-discovered roles it plays in our body.
A by-product of our bodies’ normal use of oxygen are compounds known as Reactive Oxygen Species (ROS) and also referred to as oxidants. These compounds damage our bodies on a cellular level and can even alter our DNA! One way oxidants exert their damaging force upon our cells is by tearing through the protective layers of fats (lipids) surrounding our cells. This is often done through a process involving peroxide molecules known as peroxidation. This information isn’t strictly necessary to recognize the antioxidant benefits of glycine but is useful to help digest some of the related research!
Study 1: Protects Liver from Oxidative Damage During Alcohol Consumption
Researchers gave rats alcohol for 60 days in order to damage their livers similarly to the way that a human liver might be damaged by chronic alcohol abuse. This resulted in an increased number of many types of powerful antioxidant compounds such as superoxide dismutase (SOD) catalase, and reduced glutathione. The levels of these compounds were measured in the membranes of red blood cells found in the livers of these poor little rats. Thankfully, their sacrifice helped us better understand the role of glycine in protecting our livers from oxidative damage!
Source: Cell Biochemistry and Function
Study 2: Helps Reduce Inflammation Associated with Type 2 Diabetes
Researchers often measure levels of inflammatory cytokines when investigating the damaging effects of inflammation. Tumor-Necrosis Factor-1 (TNF-1) is one of the most common of such compounds. It’s known to cause fever, inflammation, tissue damage, shock, and even death. Among diabetic patients given 5 grams per day of supplementary glycine, researchers measured a significant reduction in TNF-1 receptor levels. They also noted a 38% reduction in Type II Interferon (another pro-inflammatory cytokine) as well as a significant lowering of A1C.
Study 3: Glycine Protects Against Inflammation in Patients with Metabolic Syndrome
Metabolic syndrome is the term used to describe a group of symptoms that increase the likelihood of heart attack, stroke, and diabetes. Some symptoms include high blood pressure, high blood sugar, and excess abdominal fat. This study investigated the impact on the severity of such symptoms with daily supplementation of glycine, for 3 months. After the observation period, researchers found that glycine played a significant role in helping to balance oxidative reactions in the body such as the activity of Super Oxide Dismutase (SOD), Glutathione, and catalase. In addition, researchers noted that the expression of several anti-inflammatory genes such as CAT and SOD2 were favorably impacted.
Study 4: Glycine Restores Compromised Glutathione Production in Diabetic Patients
Antioxidants such as Glutathione help mitigate the damage from oxidative reactions in our body. When we, for whatever reason, experience a decreased level of such compounds we are at risk of experiencing higher-than-normal amounts of oxidative damage. Some diseases such as Diabetes cause higher-than-normal levels of oxidative damage. Patients with compromised levels of antioxidants, or genetic damage affecting the expression of certain oxidative pathways are present, are at higher risk of developing major diseases. This study found that patients with diabetes given glycine and cysteine supplements showed a significant increase in levels of glutathione and lowered levels of biomarkers indicative of plasma oxidative stress and lipid peroxidation. In other words, glycine was able to help produce more antioxidants which resulted in a lower level of oxidative stress!
Source: Diabetes Care
Supports Healthy Sleep Patterns
The neurons in our brains communicate with one another through synapses. These tiny little junctions between neurons are largely responsible for our brains’ ability to function. Synapses are like the doors between rooms that allow people and things to move from one place to another. Without them; our brains wouldn’t be able to function.
Sometimes neurotransmitters aren’t in proper balance and our synapses continue to fire rapidly when we want to sleep or fail to fire quickly enough when we need to focus
When we perform mentally-intensive tasks like problem-solving, memorization, or even social interactions with others, our synapses fire rapidly. When we meditate, relax, or sleep these synapses fire much slower. Sometimes neurotransmitters aren’t in proper balance and our synapses continue to fire rapidly when we want to sleep or fail to fire quickly enough when we need to focus. In the case of synapses firing too quickly, glycine has been proven to help chill things out a bit.
Study 1: Glycine Improves Sleep Quality & Increases Daytime Alertness
This study investigated the impact of 3 grams of a glycine supplement being administered to eleven patients suffering from poor sleep quality, as measured by the Pittsburgh Sleep Quality Index. Researchers measured the impact of glycine on both EEG-measured brain wave activity during sleep as well as reported sleep quality. In both measures, glycine’s influence was significantly favorable. Researchers also measured the impact of glycine on daytime sleepiness, as measured by the Stanford Sleepiness Scale. Glycine had a significant favorable impact here as well. To summarize, researchers in this study found glycine to offer significant, favorable influence on reducing the difficulty to fall asleep, the time to fall asleep, the sleep quality, daytime wakefulness, and sleep phase transitions.
Source: Sleep and Biological Rhythms
Study 2: Glycine Reduces Impact of Sleep Disturbances, Increases NREM Sleep
This study was designed to investigate the mechanisms by which glycine is able to improve sleep quality. Researchers found that when an acute sleep disturbance was initiated, the rats in this study showed a significantly-reduced onset of wakefulness. In other words, getting woke up didn’t screw up their night as badly. In addition, NREM sleep (deep sleep) was also noted as being significantly higher, after being woken up, among those mice receiving glycine. This means that glycine helped get better deep sleep after being woke up, on the preceding sleep cycle. This study also found that glycine increased blood flow which leads to a reduction in an expediated drop in core body temperature. Simply put, this study found glycine helps reduce sleep disturbances and reinforces healthy sleep patterns. Glycine supplements, as well as supplements with high-glycine percentages such as magnesium glycinate, are commonly used as natural sleep aids.
Study 3: Glycine can “Reset” Our Circadian Rhythm
This study was designed to investigate the impact glycine has on our internal clocks. There’s a tiny area of the mammalian brain called the suprachiasmatic nucleus (SCN) that sends daylight-dependent signals to our brains. These signals help regulate our daily physiological schedule and hormonal cycles. This in vitro study on the SCN of rats found that glycine was able to phase-shift circadian rhythms and confirmed this was a glycine-receptor dependent action. This means that glycine has a direct impact on our internal clock. Melatonin has been the go-to supplement for helping overcome jet-lag and initiating sleep but this study suggests glycine may also have strong potential as well. Just to be clear: this study was done on rat brains, in test tubes. The ability of glycine to impact the human circadian rhythm has not been established and we mention this study more as a conversational piece than anything else.
Source: Journal of Physiology
Skin & Joint Health
Our bodies use glycine to make many different types of protein structures including muscles, hair follicles, and cartilage. Collagen, a supplement commonly recommended for improving skin elasticity, hair growth, and nail growth, is largely consistent with glycine. Foods such as bone broths, meats, and vegetable oils are high in glycine and often recommended for skin care.
Glycine and glycine-rich collagen products have shown the ability to help support healthy skin
The glycine content of these foods is, at least partially, responsible for their association with such an application. Skincare, especially anything designed to produce more “youthful” skin, is a market notorious for misleading claims. Nonetheless, glycine and glycine-rich collagen products have shown the ability to help support healthy skin. Here are some specific cases where glycine has shown such beneficial activity when taken for joint health and skincare.
Study 1: Glycine-rich Collagen Improves Skin Moisture and Elasticity
This study investigated the impact of collagen peptide supplements on skin hydration and elasticity. Researchers compared three groups of test subject receiving either 3 grams of collagen peptides, 3 grams of collagen peptides and 500 milligrams of Vitamin C, only 500 milligrams of Vitamin C, or placebo, each on a daily basis for twelve weeks. Researchers found significant improvements in both skin elastic and skin moisture when collagen peptides were administered, with or without the vitamin C. Vitamin C did not “enhance” the benefits of collagen in this case. Collagen is a glycine-rich compound with much of its benefits likely attributable, or at the least associable, with glycine.
Study 2: Collagen Peptides Reduce Wrinkles and Increase Elastin Levels
This study observed the effects of the patented VERISOL collagen peptide product on the skin wrinkles of 57 women aged 45-65. This double-blind, placebo-controlled study administered 2.5 grams of collagen peptides daily for 8 weeks. Before, 4 weeks after, and upon conclusion of testing, researchers took measurements of skin wrinkle response. This study found a statistically significant reduction in eye wrinkles in the group of subjects given collagen peptide supplements. Additionally, researchers noted that elastin and fibrillin (both important skin elasticity biomarkers) both increased, though only elastic measured a significant increase. This study was designed to support the health claims made by a patented cosmetic cream but illustrate the impact of glycine-rich collagen peptides to reduce skin wrinkles by improving skin elasticity.
Source: Skin Pharmacology & Physiology
Study 3: Helps Skin Heal Twice as Fast
This study was designed to describe the impact of collagen supplementation on the rate which skin ulcers heal. Researchers administered collagen hydrolysate to 56 patients suffering from stage 2, 3, and 4 pressure ulcers (bed sores). After 8 weeks of treatment, patients receiving the collagen therapy were noted as healing twice as fast compared to the standard treatment. Subjects received the collagen therapy 3 times a day for 8 weeks. This study is remarkable, in that is was randomized, placebo-controlled, and demonstrated such profound efficacy in actual human subjects. Collagen and, by reasonable compositional association, glycine offer remarkable support for the healing of skin wounds.
Source: Advances in Skin & Wound Care
Supports Gastrointestinal Health
The human digestive tract is still largely a mystery. The many trillions of bacteria that reside in our guts impact our health and wellbeing in systemic ways. Conditions such as ulcerative colitis, Chron’s disease, and irritable bowel syndrome all prompt increases of oxidative stress on our digestive system.
Glycine has demonstrated the ability to help reduce the likelihood of many GI-affective disorders
As such conditions progress cellular and tissue damage is common and can lead to further complications or a progressive increase of symptoms. Glycine has demonstrated the ability to help reduce the likelihood of many GI-affective disorders from developing, has slowed their progression, as well as helped to heal their damaging effects on our digestive tissue.
Study 1: Glycine Helps Reduce GI Side Effects Caused by Aspirin
Aspirin is notorious for causing GI lesions in higher doses, especially among patients administering the compound regularly. In other words, the ones that rely on it the most. This study measured the reported GI side effects reported by patients receiving 500mg Aspirin therapy and those receiving 500mg Aspirin + 250 mg Glycine therapy. Physical damages to gastrointestinal tissues were identical though patients in the Glycine + Aspirin group didn’t report any side effects. In other words, the glycine disappeared the upset stomach and GI issues most patients complain of but didn’t stop any actual tissue damage from happening. Kind of like masking the pain. We weren’t able to find a full copy of this study and mention it here more for discussion than the assertion of glycine’s benefits on mitigating the negative subject effects of aspirin.
Study 2: Glycine Repairs Damaged Colon Tissue Following Chemotherapy
This study investigated the mitigating effects of glycine on the damage done to intestinal lining following radiation therapy in rats. Researchers compared the results of colonic skin assays from irradiated mice receiving a Glycine + L-Arginine amino acid therapy and compared them to the rats receiving the same radiation therapy but not receiving the amino acids. Researchers concluded that glycine, in particular, demonstrated significant efficacy in preserving the epithelial lining of the colon. All groups other than the one receiving glycine saw a decrease in total colon wall volume and mucosal lining. This study highlights the potential reparative and protective action of glycine towards gastrointestinal tissues. As a point of discussion, it’s likely this type of action helps explain the common recommendation of glycine-rich bone broths and soups for addressing conditions such as leaky gut syndrome.
Study 3: Glycine Stimulates Growth & Inhibits Oxidative Damage in Intestinal Tissue
Researchers in this study investigated the impact of glycine on the tissue growth and performance of neonatal pig intestines, in-vitro. Among the tissues receiving a 1.0millimolar/liter glycine treatment, researchers saw as much as 224% increases in tissue growth, 419% increases in protein synthesis, and 28% reduction in protein degradation. Additionally, glycine demonstrated significant antioxidative action by inhibiting common pro-inflammatory compounds and increasing anti-inflammatory compounds such as glutathione. This study should absolutely not be taken as a fair prediction of glycine’s action on the neonatal tissues of human intestinal tissue. However, when taken into consideration with other existing research we’ve discussed, the potential of efficacious parallels in the human body are what we consider plausible. In other words, this animal study seems to reinforce similar results from human studies.
Source: The Journal of Nutrition
Mental health is an umbrella term we’re going to use to encompass concerns and concerns such as memory, recall, learning, obsessive-compulsive behavior (OCD), schizophrenia, anxiety and even depression. If it can be traced back to the brain, we’re calling it “mental health” here for the sake of simplicity. Glycine, being an inhibitory neurotransmitter, clearly has the potential to impact our mental health.
Glycine is an inhibitory neurotransmitter and clearly has the potential to impact our mental health
Glycine’s inhibitory action makes it an obvious candidate for conditions where over-excitation of neural pathways is suspected, such as schizophrenia or anxiety. There’s been a considerable number of meaningful studies done to investigate glycine as being supportive of mental health. Here are some studies that we feel illustrate such potential particularly well.
Study 1: Long-Term Glycine Therapy Treats OCD
This single-patient case involved a young man that was forced to recoil from his social life and education due to debilitating mental illness. This illness was characterized by obsessive-compulsive behaviors and what’s known as body dysmorphic disorder (inaccurate perception of one’s physical appearance.) After the failure of several conventional therapies such as SSRIs and a worsening of symptoms following sickness, this young man was given glycine to address his primary neuronal issues at a 0.8 gram/kilogram of body weight per day dosage (50-66 grams per day!). This was done in consultation with a licensed physician but inspired by the young man and his family’s ongoing nutraceutical therapy investigation. Response to the glycine therapy was measured in terms of the severity of major life disruptions for this young man. The account of this man’s “robust” improvement following glycine therapy is a very interesting (and long) read that we suggest for anyone in a similar circumstance.
Source: Neural Plasticity
Study 2: Adjunctive Glycine Improves Conventional Psychiatric Therapies
This double-blind, placebo-controlled, cross-over study investigated the impact of glycine when used as an adjunctive (follow-up) treatment to conventional schizophrenia therapies. During this 6-week long study, researchers supplemented the existing therapies for schizophrenia patients with 0.8gram/kilogram of body weight per day glycine. Patients in this study reported very few side effects from the added glycine and saw a 23% reduction in negative symptoms. Researchers also noted that patients reported an increase in positive behavioral experiences and cognition. In other words, the subjects of this study started feeling a LOT better. It’s also noteworthy that measured levels of glycine following traditional therapies accurately predicted the clinical response, and that those with lower initial glycine levels saw the most favorable responses. This study shows great promise for glycine to improve the efficacy of conventional schizophrenia treatments but doesn’t suggest it would be an efficacious substitute therapy. In other words, don’t swap your olanzapine for glycine!
Source: Biological Psychiatry
Study 3: Glycine Demonstrates Dose-Dependent Reduction of Anxiety
In this study, researchers administered a 250mg/kg, 750mg/kg and 1250mg/kg per kilogram of body weight dose into rats. For reference, a .750mg/kg dose would be about a half-gram per day for a 160-pound person. Researchers assessed the anxiety levels of the rats while subjecting them to an elevated maze and by measuring skin conductivity. Glycine was found to provide an improvement of maze navigation speed and also resulted in significantly-lowered skin conductivity. Each of these assessments was used by researchers to asset glycine’s role as an efficacious anxiety reduction agent. Researchers noted that the .750g/kg dose produced optimal benefits while the higher dose saw no additional improvement. Just to be clear, skin conductivity and maze navigation among rats doesn’t come close to supporting the notion that glycine can treat human anxiety. Again, taken within the context of other related research, it does bring up a plausible consideration for future researchers.
Diabetes and Metabolic Disorder
Glycine has shown profound efficacy in helping to treat and manage symptoms related to diabetes and the range of conditions associated with Metabolic Disorder. This includes, in varying capacities, blood pressure, blood sugar levels, cholesterol, and A1C levels. Studies have indicated measured glycine levels may be an effective biomarker for early detection of both diabetes and metabolic disorder.
Glycine isn’t a magic bullet able to “cure” diabetes by any stretch of the imagination
That’s still a bit leap of faith, but lower levels of glycine have been noted in several studies, thus far, related to such conditions. Glycine isn’t a magic bullet able to “cure” diabetes by any stretch of the imagination. Research does support its role in helping to mitigate and decrease negative symptoms associated with diabetes and metabolic disorder.
Study 1: Glycine Reduces Inflammation and A1C Levels
This study was mentioned earlier in the context of glycine’s role in supporting antioxidation in the body. It’s important to recognize that patients suffering from diabetes are at much higher risk for tissue damage resulting from increased oxidative stress. The researchers in this study demonstrated that 5 grams of glycine a day for three months lowered measured A1C levels significantly. This study was conducted among 74 patients in Mexico City, with an average duration of having type 2 diabetes was about 5 years. There were no noticeable differences in fasting insulin levels among test and control groups. In other words, glycine makes a huge difference in lowering the oxidative damage associated with diabetes but doesn’t necessarily work to address any root causes.
Study 2: Glycine Stimulates Insulin Production
This study observed the effects of a 1mmol/kg oral glycine supplementation on plasma glycine, glucagon, and insulin. Of the nine patients participating in this study, the average dose was 4.6 grams per day. Researchers noted that serum glycine concentrations tend to peak around 40 minutes after ingestion and that co-administration of glucose + glycogen lessened overall plasma concentrations and lengthened the duration in which elevated levels were detectable. They also noted that oral glycine supplementation increases the level of serum glucagon but the intravenous administration does not. The researchers suggest this is due to a release of a glucagon-stimulating hormone (GSH) in the small intestine (would be bypassed with IV administration.) It’s important to note that, to date, there is no known hormone that acts in such a capacity. In other words, researchers of this study may have stumbled upon something entirely new! In addition, researchers demonstrated that glycine supplementation is an effective means of stimulating slight increases of insulin.
Study 3: Potential Biomarker for Insulin Resistance and Type 2 Diabetes
This study focused on investigating the levels of more than 350 metabolites in diabetic and non-diabetic test subjects to identify potential type 2 diabetes biomarkers. This study was conducted among 56 African-American women with 44 being diabetic and obese and 12 being non-diabetic. The results of this study are vast in scope and describe the role of many compounds, other than glycine, and their ratios among test groups. Glycine was noted as being significantly lower among diabetic subjects. Compounds that were dramatically higher among diabetic individuals include oleic acid, gluconic acid, fructose, and glucose.
Source: PLoS One
Dietary Requirements & Food Sources
Glycine is clearly important, as evidenced by the research discussed thus far. Glycine helps reduce oxidative tissue damage, mitigate anti-oxidative reactions, and even offer support for adequate glycolysis! Current Science categorizes glycine as “conditionally-essential” meaning that our bodies produce enough from non-glycine compounds to meet daily requirements—except in certain cases such as sickness or fasting. Recent research suggests this is a misconception and that the amount of glycine our bodies need to meet daily collagen production can’t be metabolized from diet alone. This suggests glycine would be better classified as an essential amino acid, at least in the case of collagen production. To better understand, let’s consider how the body synthesizes and utilizes glycine.
How the Body Uses Glycine
It’s not strictly important to understand the metabolic roles glycine plays in order to recognize its benefit to our bodies. Nonetheless, knowledge is power! Here’s a short list of a few things glycine helps our bodies produce:
- Hemoglobin (via porphyrin synthesis)
- ATP (via purine base synthesis)
- DNA & RNA (via purine base synthesis)
- Creatine (Muscular strength)
- Glutathione (antioxidant)
- Bile Salts (helps digestion)
- Collagen (joints, skin, hair)
This list isn’t comprehensive. It’s only meant to illustrate how vital glycine is to maintain optimal health. After all, if one were unable to produce even one of the compounds on that list it would be disastrous.
Non-Essential, Essential, and Conditionally Essential Amino Acids
The difference between nonessential vs. essential amino acids is described in the context of our diet, not our body. Non-essential amino acids are ones that aren’t essential to get from dietary sources and essential amino acids are ones that are essential to get from diet. Our bodies can’t make essential amino acids and that’s why we need to get them from dietary sources. Conditionally-essential amino acids are those that our bodies need a little help with during times of stress, such as colds or injury. Glycine is considered conditionally-essential, along with glutamine, proline, serine, and several others.
Recommended Daily Allowance
There isn’t a lot of information to help estimate the daily intake requirements for glycine. This is likely because it’s considered a non-essential amino acid, meaning that our body can synthesize it from other compounds such as serine. Research suggests that glycine is, at the very least, a conditionally-essential amino acid.
This means that during times of added stress our bodies probably need glycine from outside sources to meet metabolic requirements. WebMD says an average diet contains “2 grams of glycine” but, as usual, doesn’t provide any sort of reference. We’ll try to dig a little bit deeper, using a comprehensive 2009 analysis on the metabolic requirements of glycine as a reference.
From typical dietary sources, our body can produce 4.5 grams to 6 grams of glycine per day from using compounds such as serine found from dietary sources. One of the strongest arguments for glycine’s consideration as an essential amino acid are the increased rates of collagen production observed in several studies. This suggests that our bodies are able to utilize (and probably need) much more glycine than found in dietary sources. The glycine requirements of collagen production were the primary focus of this 2009 analysis and revealed some startling realizations.
Glycine Shortage in Collagen Production
The human body produces an estimated 3720 grams (that’s 8 pounds!) of collagen per day. Collagen is, roughly, 30% glycine. That means that our bodies need a little over 2-1/2 pounds of glycine each day just to produce collagen! Fortunately, it’s estimated that our bodies are able to recycle glycine at a rate of 95%. In other words, the glycine in new collagen is 95% glycine from old collagen. Even after accounting for recycling, however, and taking into account the glycine our body produces from dietary sources, we are still lacking about 12 grams of glycine needed to support daily collagen production. This puts us at a daily deficit of about 10 grams.
Metabolic “Balance Sheet” of Glycine
|Glycine-Requiring Process||Daily Amount|
|Metabolic Synthesis||3 grams|
|Hydrolysis of Dietary Proteins||1.5-3 grams|
|Metabolite Synthesis||(1.5) grams *|
|Collagen Synthesis||(12) grams *|
|Other Protein Synthesis||(1) grams *|
|Total||(8.5-10) grams *|
* Signifies a deficit
In other words, there’s strong evidence to suggest that we need as much as 10 grams of supplemental glycine to meet our bodies’ daily needs. It’s important to note here that the majority of the estimated deficit is with regards to the production of collagen and not of essential metabolites or anything that’d cause mortal fallout. That comes out to, roughly, a .15 gram/kilogram per day amount of supplemental glycine. Many of the studies we’ve discussed thus far have investigated doses of up to .8grams/kilogram per day without reporting adverse side effects.
Source: Journal of Biosciences
Glycine is one of the most fundamental nutrients used by our bodies to drive many essential processes. It has a role in maintaining optimal heart, brain, joint, bone, skin, and even digestive health. It’s been long understood as a conditionally-essential amino acid but evidence suggests this may not be practical, given the requirements of daily collagen production.
Glycine, along with its metabolic precursors, is commonly found in foods such as meats, fish, nuts, and some vegetable sources like artichokes. Most gelatins are basically collagen and contain around 30% glycine. One of the richest sources of dietary glycine is bone broths and home-made soups that have stock sourced from animal joints and cartilage. These are, essentially, hydrolyzed proteins that make the high concentration of glycine directly available from dietary sources.
There is a substantial amount of research to suggest glycine supplementation has many benefits for human health. In cases of cardiovascular and mental health, supplemental glycine shows tremendous promise. We believe more research is needed, at least in most cases, to make stronger assertions on the suitability of glycine therapy. Given the general lack of incentive to study the efficacy of non-patentable compounds, especially on healthy individuals, we believe that additional research will be slow. Dietary supplements are an effective source of additional glycine to help meet this deficit. Glycine is available as a free-form amino acid supplement, amino-acid chelates such as magnesium glycinate, and is also found in high percentage in collagen supplements.
As far as dosages go, the information available reports daily doses of up to 60 grams of glycine being administered on a daily basis without noticeable side effects. Toxic effects were seen in rat studies when 8g/kilogram doses were given (~600 grams for a 160 person.) On the low end, an 8.5-10 gram per day dose is needed minimal daily requirements, mostly with regards to collagen production. A lot of clinical data related to glycine comes from animal studies which don’t always translate well into human needs. Specific to glycine, and our the human body’s glycine requirement for collagen production, animals models fail particularly hard.
The sizes of rats and humans don’t scale proportionally with respect to muscle and skeletal mass. For example, skeletal mass increases by a factor of 1.1 between humans and rats while metabolic capacity scales at .85. That means that, by weight, humans have more skeletal mass than rats but less metabolic capacity. Skeletal mass requires a particularly high percentage of glycine considering the high density of collagen found there. This means that as mammals get bigger they need larger amounts of glycine to produce the collagen necessary to support their skeletal structure but have a diminished metabolic capacity to produce it. That’s likely a primary contributing factor to why large animals commonly have hip problems.
Glycine is essential to our bodies and helps drive many vital processes. There isn’t a lot of conclusive data to suggest how much glycine one needs each day, but it sounds like we’re all running at a deficit. Glycine is really important for collagen production and research supports the logical connection that glycine supplementation helps improve skin, hair, joints, and even nails. Glycine seems to have a particularly interesting role in mental health and in helping to support optimal cardiovascular health. A great first step to ensure you’re getting enough glycine would be to rotate homemade soups and bone broths into your diet. For those non-soupers out there, collagen supplements and glycine supplements are readily available in most all health food stores and online.