Glycine: The UK Keto “Sweetener” That Isn't One At All
- Matthew Caruana
- May 21
- 7 min read
A closer look at the sweet tasting amino acid
Published by Matthew Caruana | Keto Chocolate Maker & Low Carb Sweetener Specialist
If you have ever read the ingredients list on a sleeping supplement, magnesium tablet, protein powder (or premium keto chocolate bar) you may have come across glycine.
It has a bit of a clinical, almost industrial sounding name but it is completely natural, in fact glycine is one of the most common amino acids, making up around 11.5% of the body's total amino acid content and is the primary building block of collagen, which is the most abundant protein in our connective tissues.
Outside of use as a functional ingredient this building block of life has quietly developed a significant role in modern food formulation as a flavour enhancer, and sweetener.
In the UK keto food scene especially, glycine is attracting growing attention among sugar free product developers, including keto chocolate makers, searching for better tasting sugar alternatives and improvements to traditional keto sweeteners.
So what exactly is glycine, why does it taste sweet, and why is it becoming more popular in the UK low carb and keto world?
What Is Glycine?
Glycine is the smallest and simplest of the amino acids - the building blocks that make up proteins.
Its chemical structure is very straightforward: a central carbon atom attached to two hydrogen atoms, an amino group, and a carboxyl group. This simplicity gives glycine several unusual properties that distinguish it from most other amino acids.
Unlike many amino acids, which taste bitter or virtually flavourless, glycine has a distinctly mild, pleasant sweetness. The name glycine actually comes from the Greek word glykys (γλυκύς), meaning sweet.
It was first isolated in 1820 by French chemist Henri Braconnot, who noted its sugary flavour after extracting it from gelatine.
Today, glycine is widely used throughout:
Food manufacturing
Sports nutrition
Keto baking
Sugar free confectionery
Supplement powders
Pharmaceutical products
Functional foods
Why Glycine Is Becoming Popular in UK Keto Foods
The UK keto market has evolved dramatically.
Early sugar free products often relied heavily on sweeteners such as:
Erythritol
Stevia
Xylitol
While effective at replacing sweetness, these ingredients often introduced problems including:
Cooling sensations
Bitterness
Thin flavour profiles
Artificial sweetness perception
As UK keto consumers have become more sophisticated, demand has shifted toward sweetener systems that recreate the flavour profile of real sugar, especially in more premium items like keto chocolate.
This is where glycine becomes particularly interesting.
Glycine as a Sweetener
Glycine’s sweetness is generally estimated at around 60-80% as sweet as sucrose (ordinary table sugar), depending on concentration and application.
That is not unusual in and of itself, but what sets glycine apart is the quality of that sweetness.
Most literature on the subject describes glycine as producing:
Soft sweetness
Rounded flavour
Dairy like sweetness
Minimal bitterness
This makes it fundamentally different from traditional high intensity sweeteners like stevia.
Instead of delivering a sharp spike of sweetness, glycine behaves more gently, and in a way that supports and tempers the unusual characteristics of stevia.
What Makes Glycine Taste Sweet?
Like most sweet compounds, glycine interacts with the tongue’s sweet taste receptors. However, glycine activates these receptors in a relatively gentle way.
This contributes to its reputation for:
“Clean” sweetness
Mild flavour enhancement
Reduced harshness
Improved flavour blending
In practice, many people describe glycine as tasting less like an obvious sweetener and more like a subtle smoothing ingredient that makes other flavours taste better.
Why Glycine Matters in Keto Chocolate
The UK keto chocolate market has become increasingly sophisticated.
Back when I became the UKs first bean to bar chocolate maker in 2020, just making a replacement that was good enough was ok. As my understanding and use of sweeteners evolved, so my products evolved and I showed what was possible with the notoriously troublesome sweetener erythritol. While my business evolved, so did the whole keto market and low carb customers expectations along with it.
My business was always meant to replicate what a normal bean to bar chocolate maker or chocolatier would do without the customer being able to tell my products were sugar free, and increasingly that’s what consumers expect. Keto chocolate now has to resemble premium traditional chocolate in:
Texture
Sweetness profile
Mouthfeel
Melt
Dairy character
Cocoa balance
This has led manufacturers and small batch chocolate makers like myself to experiment with more advanced sweetener systems.
Glycine’s Role in Sugar Free Chocolate
In keto chocolate, glycine is useful because it can help:
Reduce bitterness from stevia
Soften the stevia sweetness spike
Improve milk chocolate flavour
Add rounded sweetness
Improve flavour integration
Create smoother sweetness transition
As the original UK keto chocolate maker, my work has always been a little avant garde and now, with the recent negative health effects of erythritol coming to light, I have moved toward a layered sweetener system rather than relying on a single ingredient. Glycine is especially useful in this context, to impart its own sweetness, but also to improve stevia perception.
Glycine in Advanced Sweetener Blends
Modern keto confectionery often combines multiple sweeteners together to imitate the physical properties and flavour of sugar.
Glycine is frequently paired with ingredients such as:
Tagatose
Allulose
Monk Fruit
Stevia
Erythritol
Milk powders
Soluble fibres
Glycerine
In these systems, glycine is often used not as the primary sweetener but as a flavour balancing component.
Food developers use it to:
Reduce bitterness
Smooth sharp sweetness peaks
Improve perceived creaminess
Support caramel or dairy notes
Blend sweetener profiles together
Reduce artificial tasting sweetness
This is particularly relevant in my artisan keto chocolate, where flavour realism has become a major competitive advantage.
How Glycine Is Used in Food Manufacturing
Beyond keto foods, glycine serves several roles in mainstream food production.
Sweetener and Flavour Enhancer
At low concentrations, glycine can improve overall flavour balance without making products overtly sweet.
It is often used to soften:
Bitter notes
Metallic flavours
Excess acidity
Harsh plant extracts
Bitter Taste Masking
Glycine is especially useful for masking bitterness from ingredients such as:
Caffeine
Minerals
Botanical extracts
Some vitamins
Certain proteins
This makes it valuable in:
Functional drinks
Protein powders
Supplement products
Fortified foods
Salt and Savoury Modulation
Interestingly, glycine may also influence savoury flavour perception.
Food manufacturers sometimes use it in reduced products like soy sauce because it can subtly enhance perceived saltiness, umami taste and overall flavour depth.
Food Preservation Applications
In some food systems, glycine contributes mild antimicrobial properties.
It is widely used in Japanese packaged foods and approved internationally, including:
UK
EU
US
Japan
In Japan, glycine is approved as food additive INS 640, and similarly in the UK & EU it has the E number E640.
*While many health food consumers are wary of E numers on ingredients lists, this can often be misplaced, as all food additives have an E number. For example, Vitamin C is E300, citric acid is E330 and Baking soda is E500. An E number doesn't mean something is unnatural or synthetic, it’s literally just a shorthand name for often, very normal ingredients*
Why Consumers Buy Glycine
Although keto sweetening is one of its fastest growing uses, consumers buy glycine for many different reasons.
1. Keto and Low Carb Baking
The keto community has developed strong interest in glycine because it provides mild sweetness without behaving like traditional sugar.
Its soft sweetness profile makes it especially useful in recipes where stevia or erythritol alone taste bitter, or too aggressive.
2. Protein and Collagen Products
Collagen contains large amounts of glycine, so consumers frequently encounter it in:
Collagen powders
Protein blends
Meal replacements
Recovery drinks
Some consumers also purchase pure glycine powder separately because it mixes easily into drinks and has a naturally pleasant flavour.
3. DIY Supplement Stacks
Among consumers who build custom supplement mixtures, glycine is often considered a practical foundational ingredient because it is:
Inexpensive
Easy to mix
Mild tasting
Highly soluble
Bulk glycine powder is especially popular among consumers who prefer purchasing individual ingredients rather than pre made formulations.
4. Sports Nutrition Products
Many sports nutrition products include glycine because it contributes to amino acid content while also improving flavour.
Its mild sweetness helps make:
Pre workouts
Recovery drinks
Protein shakes
Amino acid blends
more palatable without requiring additional sugar.
5. A Sleep Enhancing Supplement
Glycine is increasingly becoming a popular, non-sedating dietary supplement used to improve sleep quality, shorten the time it takes to fall asleep, and reduce daytime fatigue.
Unlike prescription sleeping pills that knock out the central nervous system, glycine works by optimizing the body's natural circadian rhythms and temperature controls.
How Glycine Promotes Sleep
Lowers Core Body Temperature
Calms Neural Activity
Boosts Serotonin
According to human polysomnography (sleep-tracking) studies, a single dose of 3g, taken 30-60 minutes before bed yields several observable improvements:
· Faster Sleep Onset
· Deeper Slow Wave Sleep
· Less Daytime Brain Fog
Many people take it as pure L-glycine powder, but it is also frequently consumed as Magnesium Glycinate. Magnesium glycinate capsules are heavily favoured because they also contain magnesium, giving you a double benefit since magnesium also relaxes muscles and improves sleep quality.
What Does Glycine Actually Taste Like?
If you have never tasted pure glycine, the flavour can be surprising.
The sweetness is subtle but genuinely pleasant.
It does not have:
The intense sweetness of sugar
The lingering effect of stevia
The cooling sensation of erythritol
Instead, many people describe glycine as:
Clean
Soft
Rounded
Slightly creamy
The only downside with glycine is that after the sweetness subsides it does have a faint Umami (savoury) flavour coming through. Nowhere near the level of the sweetness, but nonetheless an important factor to consider when using glycine as a sweetener. This is why it is best used more as a supporting component in a multi sweetenr system, than as the sole sweetener.
Buying Glycine in the UK
Consumers purchasing glycine will usually encounter:
Food Grade Glycine
Suitable for:
Food
Drinks
Keto baking
Supplements
Chocolate making
This is the most common version sold online and in supplement retailers.
Pharmaceutical Grade Glycine
Produced with different standards for medical and pharmaceutical use.
Food grade and pharmaceutical grade are not interchangeable - if you are buying glycine, or any other food supplement, always make sure it is food grade
Why Glycine Is Important for the Future of UK Keto Chocolate & Confectionary
With the UK keto food industry moving away from erythritol, attention is shifting back to stevia and other alternative sweeteners.
Stevia is often perceived as bitter in large concentrations, and around 6% of people perceive Steviol glycosides primarily as bitter, with very little sweetness.
As stvia is many times sweeter than sucrose (normal sugar), to replace the bulk of normal sugar it has traditionally been paired with a second sweetener of lower potency, usually erythritol.
Glycine’s unique bitterness reducing quality, its mild sweetness and gentle sweetening perception curve make it an ideal accompaniment to stevia extracts.
Glycine (E640 / INS 640) is approved as a food additive in the EU, UK, US (GRAS), Japan, and many other markets. As with any supplement or food additive, purchasing from reputable suppliers with transparent quality standards is advisable.
This article is for informational purposes only and does not constitute dietary or medical advice. Always consult an appropriate professional if you have specific health requirements or medical conditions.
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