Taurine and glycine are two amino acids your body makes itself and also gets from food. Research suggests taurine may give a small lift to endurance performance and is well tolerated at typical supplement doses, while a few small studies suggest 3 g of glycine before bed may help poor sleepers feel more rested. Here is what each one does, what the evidence says and how they are usually taken.
What is taurine good for?
Taurine is a sulfur-containing amino acid that the body makes from cysteine, and it is especially abundant in skeletal muscle. Animal foods are the richest dietary sources (Kurtz and colleagues, 2021).
Exercise. A 2018 meta-analysis of 10 studies found taurine gave a small improvement in endurance performance at doses of 1 to 6 g. A single dose worked about as well as taking it for up to two weeks, and larger doses did not work better (Waldron and colleagues, 2018). A broader 2021 review of 19 studies was more cautious: it said limited and varied findings rule out firm conclusions on aerobic and anaerobic performance, and findings on recovery were mixed. Where benefits were seen, the dose was usually 1 to 3 g taken 1 to 3 hours before exercise.
Ageing. A 2023 study in Science reported that taurine levels fall with age and that taurine supplements extended lifespan in mice and worms (Singh and colleagues, 2023). Human data has not backed this up. A 2025 study of three human groups found blood taurine stayed the same or rose with age (Fernandez and colleagues, 2025), and a study of 137 men aged 20 to 93 found no link between taurine and age, muscle mass or strength (Marcangeli and colleagues, 2025). Any anti-ageing benefit in people is unproven.
Is taurine safe?
For healthy adults, taurine appears to be well tolerated. A 2008 risk assessment found strong evidence of no harmful effects at supplement intakes up to 3 g a day. Higher amounts have been tested without problems, but there is not enough long-term data to be confident about them (Shao and Hathcock, 2008).
Taurine in energy drinks. In Australia, energy drinks are regulated as formulated caffeinated beverages. The Food Standards Code caps taurine at 2,000 mg in the daily amount stated on the label (Schedule 28), and the label must say the drink is not recommended for children, pregnant or breastfeeding women, or people sensitive to caffeine (Standard 2.6.4). Those warnings are about the caffeine, which our guide to pre-workout caffeine and the Australian rules covers in detail.
If you are pregnant or breastfeeding, under 18, have a medical condition or take regular medication, check with your GP or pharmacist before taking taurine.
Glycine benefits: what glycine does
Glycine is the simplest amino acid. The body makes it from other nutrients, mainly in the liver and kidneys, and uses it to build glutathione, haem (part of haemoglobin), creatine and nucleic acids. It is also part of the bile acids that help digest fat, and it plays a role in nerve signalling. Researchers describe it as conditionally essential, meaning the body may not always make enough (Wang and colleagues, 2013). Glycine makes up every third amino acid in collagen, and meat, fish, dairy and legumes all supply it (Razak and colleagues, 2017).
Australia has no recommended daily intake for glycine, and much of the research on glycine supplements has been done in animals or small groups of people.
Glycine for sleep: what the small studies show
Most of the human research on glycine and sleep comes from three small Japanese studies, each using 3 g of glycine before bed:
- In a crossover trial in people who reported poor sleep, glycine improved next-morning ratings of fatigue, liveliness and clear-headedness compared with placebo (Inagawa and colleagues, 2006).
- In volunteers with unsatisfying sleep, glycine improved self-rated sleep quality, and overnight sleep monitoring showed they fell asleep and reached deep sleep sooner. Daytime sleepiness was lower too (Yamadera and colleagues, 2007).
- In seven healthy men whose sleep was cut by a quarter for three nights, glycine reduced next-day fatigue and improved an attention test (Bannai and colleagues, 2012).
These results are encouraging but limited. The groups were tiny, the studies were short, and several of the researchers worked for Ajinomoto, a company that makes glycine. Rat research suggests glycine may work partly by lowering core body temperature (Bannai and Kawai, 2012). There are no large independent trials, so think of glycine as something that may help some people rather than a sleep fix. If poor sleep goes on for weeks, see your GP.
How to take taurine and glycine
Follow your product label. For context, this is how the research used them:
| Taurine | Glycine | |
|---|---|---|
| Amounts in studies | 1 to 6 g, often 1 to 3 g | 3 g |
| Timing in studies | 1 to 3 hours before exercise | Before bed |
| Safety reference | No harmful effects seen up to 3 g a day | No official upper limit; studied short term |
| Common forms | 500 mg or 1,000 mg capsules, or powder | 1,000 mg capsules, or powder |
Powders make gram-sized doses easy, while capsules suit people who prefer not to measure. Three 1,000 mg glycine capsules equal the 3 g used in the sleep studies.
Products to look at
- NOW Foods Taurine 1000 mg: 1,000 mg of free-form taurine per vegetarian capsule.
- Life Extension Taurine 1,000 mg: 1,000 mg per vegetarian capsule, 90 capsules.
- Switch Taurine: 100% pure taurine powder, 1 g serve, 200 serves.
- NOW Foods Glycine 1000 mg: 3 g of free-form glycine per 3 vegetarian capsules.
- Life Extension Glycine 1000 mg: 1,000 mg per vegetarian capsule.
See the full amino acid range, or read why sleep supplements are becoming part of recovery.
FAQs
What is taurine good for?
Taurine is an amino acid found mostly in animal foods and also made by the body. A 2018 meta-analysis found that 1 to 6 g taken before exercise gave a small improvement in endurance performance, though a broader 2021 review said the evidence is too limited and varied for firm conclusions. Claims that taurine slows ageing come from animal research and have not held up in recent human studies.
Is taurine safe to take every day?
For healthy adults it appears to be well tolerated. A 2008 risk assessment found strong evidence of no harmful effects at up to 3 g a day from supplements. In Australia, energy drinks can contain up to 2,000 mg of taurine in their labelled daily amount. If you are pregnant, under 18, have a medical condition or take medication, ask your GP or pharmacist first.
Does glycine help you sleep?
It may help some people. Three small Japanese studies found that 3 g of glycine before bed improved how rested people felt, and one using overnight monitoring found people fell asleep sooner. The groups were tiny and several researchers worked for a glycine maker. There are no large independent trials, so see your GP if poor sleep continues.
How much glycine should I take for sleep?
The sleep studies used 3 g taken before bed, which is three 1,000 mg capsules or a measured serve of powder. That is what researchers tested, not a personal recommendation, so follow your product label. There is no official upper limit for glycine, but research on long-term use is limited, so check with your GP or pharmacist if you take medication.
What are the main benefits of glycine?
Glycine helps the body make glutathione, creatine and haem, is part of the bile acids that help digest fat, plays a role in nerve signalling and makes up every third amino acid in collagen. Meat, fish, dairy and legumes all provide it. As a supplement, its most studied use is a 3 g dose before bed for sleep quality, based on small studies.
Sources: Kurtz and colleagues, JISSN (2021); Waldron and colleagues, Sports Medicine (2018); Shao and Hathcock, Regulatory Toxicology and Pharmacology (2008); Singh and colleagues, Science (2023); Fernandez and colleagues, Science (2025); Marcangeli and colleagues, Aging Cell (2025); Food Standards Code, Schedule 28; Food Standards Code, Standard 2.6.4; Wang and colleagues, Amino Acids (2013); Razak and colleagues, Oxidative Medicine and Cellular Longevity (2017); Inagawa and colleagues, Sleep and Biological Rhythms (2006); Yamadera and colleagues, Sleep and Biological Rhythms (2007); Bannai and colleagues, Frontiers in Neurology (2012); Bannai and Kawai, Journal of Pharmacological Sciences (2012); product label images.
Order online with Australia-wide delivery, free on orders of $99.99 or more, or visit a Supps247 store in Melbourne, regional Victoria or Brisbane to compare products in person before you buy. Members can use our price match guarantee on full-priced items.
Always read the label and follow the directions for use. If you have a medical condition, are pregnant or take regular medication, check with your doctor first.
