Update 9/22/22. GlyNac refers to supplements that contain a combination of glycine and N-acetyl cysteine (NAC). These amino acids are used to raise glutathione levels. Glutathione is an antioxidant and this substance decreases as we get older. So can GlyNac slow aging? In this GlyNac review, you will discover the human research on these amino acids. You'll also learn about the side effects and dosages too. Affiliate disclosure. If you click on a link and purchase something, this website may make a small commission. The company pays for this. Not you. For more info see the affiliate disclosure page.
GlyNac Ingredients
Supplements of this type contain only 2 ingredients:
- Glycine
- N-acetylcysteine (NAC)
What are these? Glycine is an amino acid. N-acetylcysteine (NAC) is available as both a drug and dietary supplement. As a prescription drug, NAC helps the body recover from acetaminophen (Tylenol) toxicity. However, as a dietary supplement, NAC is a well-known way to raise glutathione levels. Glutathione is a powerful antioxidant that the body makes naturally. As we get older glutathione levels can decline. The NAC supplement is able to boost our levels because it supplies the body with the sulfur-containing amino acid, cysteine.
Glycine
Glycine is a non-essential amino acid. This means that the body makes normally all the glycine it needs. Like NAC, glycine also appears to be needed to produce the glutathione antioxidant substance.
N-acetyl cysteine (NAC)
N-acetyl cysteine (NAC), also called acetylcysteine is an antioxidant that can reduce inflammation too. It's also been shown to reduce homocysteine levels, a substance linked to heart disease. NAC is also a prescription drug used to treat acetaminophen/Tylenol poisoning. NAC is used in supplements because it is a source of the amino acid, cysteine. One thing to remember is that foods contain cysteine while NAC is produced in the lab and not found in foods.
How Does GlyNac Work?
Aging is associated with both increased free radicals and mitochondria dysfunction. Research suggests that both of these factors play roles in aging and aging-related disease such as:
- inflammation
- insulin resistance
- loss of muscle strength
- endothelial blood vessel dysfunction
- increased dementia risk
Glutathione is a potent antioxidant compound that's normally made in the body, although its production is impaired in older adults. GlyNac is thought to work
because it contains both glycine and cysteine, amino acids needed for glutathione production. Older adults have been shown to have lower levels of both of these amino acids.
In one study, glutathione synthesis increased 231% when older adults were given glycine and cysteine amino acids. Free radical damage was also reduced. By providing precursor nutrients needed for glutathione production, the hope is GlyNac can help offset aging-related diseases.
GlyNac Research
So is there any proof this amino acid combination helps older folks age better? Here's a summary of what we know so far.
Study 1
In one study, researchers at Balor college in Houston Texas recruited 8 older adults in their 70s and 80s and gave them glycine and cysteine amino acids for 24 weeks. They were also given several medical tests before and after and compared their results to 8 younger people in their 20s and 30s who did not take the supplements.
After 24 weeks, the supplement promoted:
- 200% increase in glutathione in red blood cells
- 75% reduced TBARS
- 49% reduced CRP levels (reduced inflammation)
- 55% lower insulin levels
- 9% lower blood sugar levels
- 21% reduced muscle breakdown
- 4% reduction in fat mass (but no weight loss)
In addition, the supplement significantly improved results on all cognitive function tests too. Equally interesting is that the people could walk faster and their handgrip strength increased as well, suggestings GlyNAC may help older folks get around better as they perform their daily activities. The researchers then stopped the supplements for 12 weeks to see what would happen. When they did this, they noted all the benefits of the supplement started to decline.
Study Problems
No doubt this investigation is impressive but a few things to keep in mind include:
- this was a small study of only 8 people.
- There was no placebo group
- There was no group that only received one of the amino acids
Study 2
In an earlier study, 8 older adults were given glycine and NAC supplements for 14 days and compared to 8 younger people. After two weeks, glycine and NAC supplements increased glutathione levels in older folks by 95% and increased the production of glutathione by 231%. This corresponded to significantly lower oxidative stress too.
Study Problems
- It was a small study
- There was no placebo group
- There was no group that only received one of the amino acids
- Intravenous infusions of glycine and NAC were used. Oral dietary supplements were not used.
Study 3
Diabetes is associated with reduced glutathione levels. To see if those levels could be restored, researchers gave glycine and cysteine to 12 people with type 2 diabetes for 2 weeks. After 14 days, glutathione levels increased by 64% and increased the synthesis of glutathione by almost 200%. While impressive, the levels were still lower than for younger people who did not have diabetes. It should be noted that the people recruited for this study had “uncontrolled diabetes” with hemoglobin A1C levels between 8 and 10, which is higher than recommended.
Study problems
- It was a small study (only 12 people)
- The people had uncontrolled type 2 diabetes
- There was no group where people only received one of the amino acids
- Glycine and NAC were “infused” – injected – into the people. Dietary supplements were not used.
Study 4
This is an investigation of people with HIV. Here, 8 HIV-positive men and women were given glycine and NAC supplements and compared to 8 people who did not have the virus. During this three-month investigation, the HIV-infected people took 7 grams of glycine and 9 grams of NAC supplements per day. Results revealed people with HIV who used the GlyNac formula had these benefits:
- improved glutathione synthesis (340% increase in muscle)
- 81% decrease in TBARS
- reduced body mass index, less body fat (about 5 pounds less), and less upper body fat
- better functioning mitochondria
- 69% reduction in insulin resistance
- 40% reduction in liver fat in those who had non-alcoholic fatty liver disease
- 7% to 25% improved exercise capacity
- reduced muscle breakdown
- lower blood pressure
- 18% to 41% improved cognitive performance with increases in brain-derived neurotrophic factor (BDNF) – which helps with long-term memory
- reduced inflammation (54% reduction in CRP levels)
When the supplements were stopped, benefits started to go away, suggesting that long-term supplementation by those with HIV may be required.
Study problems
While this study is intriguing, it only had 8 people. It needs to be replicated with more people.
Some say black seeds can reverse HIV and there is some research on this. See these videos for more insights
Study 5
In this investigation, mice were given the GlyNac formula. Here, it was reported male and female mice that consumed glycine and N-acetyl cysteine lived 24% longer than mice that did not consume these supplements. Those mice also had improved glutathione synthesis.
Study problems
It's a mouse study.
Study 6
This investigation involved people with type II diabetes and is related to the third study summarized above. Ten people with poorly controlled type II diabetes were given glycine and NAC for two weeks. The amounts used were 100 mg per kg of glycine and 100 mg per kg of NAC. What does that mean for you? If you weighed 200 pounds (91 kg), the dosage used was about 9 grams per day of both glycine and NAC.
It was reported that after just 2 weeks, people experienced a 30% improvement in the ability of their mitochondria to burn fat and a 47% improvement in the mitochondria's ability to burn glucose. In other words, their mitochondria appeared to work better. In addition, their insulin resistance improved by 22%, and the fats in their blood declined by 25%.
Study problems
This investigation did not have a placebo group to compare the results to and contained a small number of people.
Study 7
This study involved 24 older adults and 12 younger adults who were given GlyNac supplements or a placebo for between 2 and 16 weeks. The dosage used was 100 mg /kg for both glycine and NAC. After 16 weeks, it was reported that in older adults GlyNac had the following effects:
- raised glutathione in muscle cells by 164% – to levels similar to younger adults
- reduced systolic blood pressure
- decreases waist circumference (but not body weight or body mass index)
- increased walking speed to that of younger adults after 16 weeks
- increased upper and lower body strength
- reduced TBARS and oxidative stress (free radical damage)
- improved mitochondria functioning
- reduced inflammation
- improved blood vessel endothelial function
- No changes in telomere health were seen
These improvements were not seen in younger adults who took GlyNac supplements.
Study problems
A small number of participants.
Video Review
Here's a quick video I put together.
Watch on my Youtube channel if you prefer
Where Do You Buy GlyNac Supplements?
While there are sure to be GlyNac capsules sold in stores like Costco, Walmart, Vitamin Shoppe, etc. that cost an arm and a leg, you should remember both amino acids can be purchased individually, saving you lots of money.
Both glycine and cysteine are non-essential amino acids. This means your body makes both of them. While it's possible we may not make enough as we get older, younger, healthy people may already produce all they need. So supplements may not be needed for them. Studies suggest for older adults they may be required.
What Foods Contain GlyNac?
Food is a combination of many amino acids and other nutrients. Remember that NAC is a source of the amino acid, cysteine. While there are no foods that contain NAC, here are some foods containing glycine and cysteine.
| Glycine foods | Cysteine foods |
| Bone broth | Beef |
| Jello | Chicken |
| Beef | Turkey |
| Chicken | Red peppers |
| Beans | Onions |
| Fish | Eggs |
| Spirulina | Garlic |
GlyNac vs. Celltrient Protect
Celltrient Protect is an anti-aging supplement by the Nestle company. The idea behind the Celltrient line of supplements is to address age-associated cellular decline. Each packet of Celltrient Protect contains 1.2 grams of glycine and 1.2 grams of (NAC). If you opt for the Celltrient capsules, then 2 capsules contain 600 mg of glycine and 600 mg of NAC. Since research suggests these amino acids raise glutathione levels, it's possible the Celltrient Protect supplements would also.
See the Cellutrient Energy review
FAQ
What's the difference between NAC and cysteine?
The biggest difference is that cysteine is an amino acid. (NAC) is a dietary supplement that provides the body with cysteine. The body makes cysteine but it does not manufacture NAC. NAC has proven to be an effective way to boost glutathione levels in cells.
How are cysteine and cystine different?
They are very similar. Cystine is formed by two cysteine amino acids bonded together. Another difference is that cysteine is better absorbed than cystine.
What's better: glycine or cysteine?
The research so far does not indicate which amino acid raises glutathione the most. However, some research suggests that – just as with cysteine – a lack of glycine also slows down glutathione production significantly. Based on this it does make sense both nutrients might be better than either amino acid used separately. Research needs to confirm this though.
What is GlyNase?
GlyNase is a sulfonylurea blood sugar-lowering drug used to treat diabetes. Don't confuse GlyNase with GlyNac supplements. They are not the same thing.
What about GlyNac eyedrops?
Some brands of eye drops may contain N acetylcarnitine (NAC). This compound is different than N-acetylcysteine. Don't confuse the two. They are not the same thing. NAC Eye drops are different than GlyNac capsules.
Glutathione vs glutamine. What's the difference?
Both words sound similar but they are different. Glutathione is an antioxidant compound. Glutamine is an amino.
Does GlyNac raise NAD+ Levels?
Boosting cellular NAD levels is a popular buzz-phrase in the world of anti-aging medicine. NAD+ helps us make cellular energy (ATP). We tend to make less NAD+ as we get older. Some research suggests raising NAD+ levels may slow down some signs of aging. Human clinical studies have not compared GlyNac to popular NAD+ booster supplements like NMN or nicotinamide riboside.
My Youtube channel has several NMN and NR videos. See the proof for yourself.
What's the best GlyNAC dosage to use to achieve antiaging benefits?
This is the big question. The studies above used the same amounts: 1.33 mmol per kilogram per day of NAC and 0.81 mmol per kilogram of cysteine per day. Obviously, these dosages mean little to most people because supplements are not measured in millimoles. More to the point, the dosages used were based on how much people weighed. The more they weighed, the greater the dosages used. If considering supplements, I like the Life Extention brand of these nutrients.
If we consider a person who weighs about 150 pounds then the dosages are around 7 grams of glycine and 9 grams of NAC. This is a lot and more than most supplements contain. Regardless of what amounts of GlyNac were used in research, there really isn't enough evidence to suggest an optimal amount for everybody. That said, 600 mg of each may be a starting point. Remember both glycine and cysteine are made by the body. It's quite possible younger, healthier people already make enough, making supplements unnecessary.
What do the studies have in common?
The studies summarized above were conducted in conjunction with Baylor University in Texas which holds the US patent on GlyNac. Baylor licenses the supplement to other companies such as Nestle and perhaps others that produce their own line of anti-aging supplements.
GlyNac Side Effects
Human studies suggest that for most people both glycine and cysteine are safe with no significant side effects. That said, some things to consider include:
- Start with less for the first week. If you were to have adverse reactions, taking less should help minimize them.
- Ask your doctor if pregnant or breastfeeding or take any medications
- Stop taking at least 2 weeks before having surgery
- Glycine may interfere with schizophrenia drugs
- N-acetyl cysteine (NAC) can lower blood pressure. If combined with hypertension medications, blood pressure may go too low. It may also interact with blood thinner drugs too.
- So far there is no reliable proof GlyNac helps with Covid-19 infection. See the COVID supplements review.
- Be careful with intravenous N-acetyl cysteine infusions. Some reports link IV NAC infusion with kidney and liver failure including some deaths. This has not been reported with oral supplements.
- If you have cancer speak to your doctor. Glutathione is an antioxidant. As such it's possible it may reduce the effectiveness of chemotherapy and radiation therapy.
So, is GlyNac Legit From An Antiaging Perspective?
While the body is able to make both glycine and cysteine amino acids, the research seems to show their levels may be lower in some older folks. This may be due to reduced synthesis or a poor diet – or both. Preliminary research also appears to show supplementation with these nutrients not only raises glutathione but may also do other things such as improve walking speed and strength in older adults. Before overpaying for supplements that contain these ingredients, remember you may be able to save money by purchasing them separately. While the research is intriguing, I'd like to see a couple of larger studies to know for sure if glycine plus N-acetylcysteine (NAC) raises glutathione better than NAC alone.