I choose the supplements I take after carefully considering their benefits and their safety. I wasn’t sure about glycine but there’s one impact we’ve seen in studies that convinced me to start taking it. We’ll walk through those studies plus look at a number of other promising health benefits of glycine.
And just because I take a supplement does not in any way mean that you should as well.
Table of Contents
- Longevity?
- A Bit More on Glycine: What Does It Do in the Body?
- Benefits with Stronger Evidence
- Potential Benefits Needing Further Exploration
- Sources, Supplements, Safety
- Reference List
Longevity?
One of the more tantalizing discoveries with glycine is connected to lifespan.
First, I need to briefly explain the background.
Researchers have discovered that diets low in methionine can extend the lifespan of rodents. Methionine is an amino acid, one of the building blocks of proteins. When it’s broken down in the body, one of the products is another amino acid, homocysteine. When homocysteine levels are too high, this correlates with increased risks for certain health problems like heart disease.
And this is where glycine comes in. It appears to reduce the toxic effects of too much methionine in mice [1].
So this sparked an idea for scientists to explore. Maybe boosting the intake of glycine can have a similar effect on longevity as reducing the consumption of methionine.
The research was carried out through the Interventions Testing Program. It’s an initiative funded by the National Institute on Aging in the U.S. Its goal is to identify promising substances that could extend lifespan or improve health as we age. They tested the effects of supplementing with glycine in mice.
The results were encouraging. Glycine led to a small but statistically significant lifespan increase of about 4-6% on average across three independent testing sites [1].
Though this is an area of ongoing research, it looks like there are at least two mechanisms involved here. The first is that glycine helps counteract too much methionine. It seems to be involved in breaking it down and clearing it from the body. But evidence also suggests glycine can activate autophagy [2].
Autophagy is the process where our cells break down and remove damaged or worn-out parts. It’s a bit like trash collectors for a city. It’s a crucial process that maintains cellular health.
A Bit More on Glycine: What Does It Do in the Body?
Though these research results are exciting, we’re not mice. We don’t yet know if glycine supplementation can extend lifespan in humans. But we do have some data that reveal positive health impacts in several important areas. After taking a look at these, I’ll explain why I personally take glycine.
Let’s start with a fuller picture of what glycine does in the body. As I already mentioned, it’s an amino acid that helps build proteins. It’s one of the key ingredients in collagen, the most abundant protein in the body. Collagen provides structure throughout our bodies in tissues like skin, bones, tendons, and blood vessels. It’s also part of other important molecules that contribute to muscle function, oxygen transport in the blood, protection against oxidative stress, and fat digestion.
Glycine is part of the regulation of blood sugar and immune response. It plays a role in removing toxins. And it helps control nerve signals.
Despite being involved in so many important functions, glycine isn’t considered an essential amino acid. That’s because our bodies can make it. But evidence suggests we probably need to also get glycine from our diets to have enough [3].
Benefits with Stronger Evidence
So what are some potential benefits from boosting our intake? There are two areas where we presently have pretty compelling evidence.
1. Sleep
The first is sleep. A small, double-blind study published in 2006 looked at the impact of glycine supplements on sleep quality. They recruited people who reported having trouble with sleep. Before bed, participants took either a placebo or glycine. Then they completed a questionnaire the next day. Glycine supplements significantly improved their ratings of liveliness and clear-headedness, and reduced their feelings of fatigue [4].
A similar study took a deeper look by measuring activity during sleep in addition to asking participants how they felt. Those who took the supplement reported experiencing better sleep and were also less sleepy during the day. Objective measures backed up these impressions: people fell asleep and reached deep sleep faster, and they performed better on memory tests the next day [5].
I want to highlight something the monitoring equipment allowed researchers to see: glycine didn’t change sleep architecture [5]. This means the normal pattern of sleep stages wasn’t upset. Many common medications that help people sleep can disrupt our sleep patterns. This often leaves us feeling groggy and less alert the next day [5]. Glycine seems to provide benefits without that drawback.
Another study was similar, except participants had their normal sleep reduced by 25% for three nights in a row while they took a glycine supplement or placebo. Researchers measured daytime sleepiness and performance. Those who took glycine had reduced fatigue and sleepiness [6].
So what’s going on here? Why does glycine help with sleep? A rodent study indicated that glycine works by influencing the biological clock in our brains. Specifically, it triggers increased blood flow to the skin, which cools us down—this is a normal part of falling asleep [7].
And this is one of the reasons why taking a bath or shower before bed is a good idea. The shower raises our body temperature, then when we get out of the shower our body temperature plummets, and it’s that change in body temperature that signals to the body that it’s time to fall asleep.
This research is really significant. Quality sleep is hugely important to our health. When our sleep is messed up, that’s linked to increased risks of all-cause mortality, heart attacks, and strokes [8].
And this is why I include glycine as one of the ingredients in my new Sleep supplement. But just because I take a supplement, this doesn’t in any way mean you need to also.
2. Metabolic Health
The second area where we have good evidence for glycine’s benefits relates to metabolic health. This is about our body’s ability to efficiently process, store, and use energy from the food we eat. Think of things like blood sugar control, cholesterol levels, and body composition.
For instance, one small study tested glycine in individuals with a higher risk of developing type 2 diabetes. It found that glycine boosted the amount of insulin produced after a meal and therefore helped process the food more effectively [9].
Another study established positive effects on body composition in rodents. While on a calorie-restricted diet, mice taking glycine burned more fat and lost less muscle than the mice who weren’t consuming glycine [10].
Both of these studies suggest glycine has the ability to positively impact our bodies’ energy metabolism.
Two other studies relate to preventing damage when our metabolic health is out of balance. Conditions like obesity and diabetes create oxidative stress and inflammation. They both boost the production of free radicals and pro-inflammatory substances. This can lead to significant systemic harm.
One study looked at the effect of glycine supplements in those with metabolic syndrome. Participants got a glycine supplement or a placebo daily for 3 months, and researchers measured markers of oxidative stress. They found that glycine helped: oxidative stress went down [11]. This makes sense, as glycine is one of the three building blocks of a powerful antioxidant called glutathione.
Interestingly, blood pressure also fell for men in the treatment group, which is great for heart health [11].
Let’s next look at inflammation. Researchers wondered about the effects of glycine in patients with obesity and type 2 diabetes. Both of these conditions often involve chronic low-level inflammation. This happens because the body is producing too many pro-inflammatory substances and not enough anti-inflammatory ones.
Glycine’s effects on inflammation have been widely studied. Scientists have found it decreases pro-inflammatory substances and increases the presence of anti-inflammatory ones [12].
Potential Benefits Needing Further Exploration
Besides benefits for sleep and metabolic health, there is promising research pointing to further effects of glycine. We’ll quickly look at just two before considering the right dose for glycine supplements.
3. Heart Health
We’ve already seen one study found glycine supplements slightly lowered blood pressure. Researchers have been looking more deeply at the connection with heart health.
One large analysis examined a group of over 4,000 patients with suspected heart disease over a follow-up period of about 7 years. They looked at the association between glycine levels in the blood and heart attacks. There was an inverse relationship: the lower a person’s glycine levels, the more likely a heart attack was [13].
This cohort study established an association, but it didn’t prove causation. That still leaves a question of whether glycine is driving better heart health—and if so, how?
One interesting analysis approached these questions through genetics. Researchers looked at a massive genetic database and found people with genetic variants associated with higher glycine levels. Then they checked to see if those people also had better heart-health outcomes—and they did. That gave them reason to think higher glycine levels might be causing the better outcomes [14]. Part of the effect is thought to be mediated by lower blood pressure [14].
We’ve also seen that glycine affects oxidative stress and inflammation, both important factors in heart disease. So it’s likely they play a role here as well. We’ll need further clinical trials to confirm the causal mechanisms involved.
4. Brain Function
Glycine is like a key that helps unlock a special door in the brain called the NMDA receptor. This door only opens when two keys are used at the same time: one is glycine, and the other is a chemical called glutamate. When both keys fit, it opens the door to important processes like learning and memory.
There are certain problems in the brain linked to poor function of NMDA receptors. One of them is schizophrenia. Researchers in one study found that patients with schizophrenia had low levels of glycine compared to controls. The same was true with patients who had major depression [15].
Another small study found that adding high-dose glycine to standard treatments for schizophrenia resulted in a 23% reduction in negative symptoms [16].
Sources, Supplements, Safety
This is just a sample of the areas where glycine is showing promise for our health. But let’s get practical. How should we approach supplements? And why do I personally think they’re worth it?
Let’s start with this question: How much glycine do we need? As we noted, our bodies can make it. But it appears we need to also get some from our diet to have the right amount. Many studies, like the ones on sleep, use a daily dose of 3 g. And authors of a recent review article recommend an intake of about 1.5–3 g/day to meet our needs [3].
Glycine is found naturally in certain foods. The best sources are animal products, particularly in tissues that have a lot of collagen, like skin. You can also find some in legumes, nuts, and seeds.
In supplements, glycine is typically in a free, pure form. It’s super easy for the body to absorb.
So why do I personally take glycine as part of my Sleep supplement? As I’ve looked at the research, it’s clear that glycine is important for a host of bodily functions. Research is revealing benefits in a wide range of areas.
But you might wonder: Isn’t a lot of that research still pretty preliminary? Sure. But here’s where I always look at potential benefits versus potential risks. When it comes to glycine, the safety profile is great. It is categorized as generally recognized as safe by the FDA. And the studies looking at supplementation don’t report any worrying adverse effects. Plus, it’s an amino acid our bodies make and that we get in our diet every day.
In other words, the evidence says supplementing with glycine is generally safe at typical doses in the range of about 3 g/day. And it has some fairly well-established benefits, particularly for sleep. So to me, it makes total sense to make sure I’m getting enough through a supplement.
Reference List
1. https://pmc.ncbi.nlm.nih.gov/articles/PMC6516426/
2. https://pubmed.ncbi.nlm.nih.gov/37004845/
3. https://www.mdpi.com/2813-2475/3/2/16
4. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1479-8425.2006.00193.x
5. https://onlinelibrary.wiley.com/doi/full/10.1111/j.1479-8425.2007.00262.x
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC3328957/
7. https://www.nature.com/articles/npp2014326
8. https://pubmed.ncbi.nlm.nih.gov/28889101/
9. https://pubmed.ncbi.nlm.nih.gov/11456285/
10. https://www.sciencedirect.com/science/article/abs/pii/S0261561415002411
11. https://pubmed.ncbi.nlm.nih.gov/24144057/
12. https://pmc.ncbi.nlm.nih.gov/articles/PMC10379184/
13. https://www.ahajournals.org/doi/10.1161/jaha.115.002621
14. https://pmc.ncbi.nlm.nih.gov/articles/PMC6400990/
