Erythrol ((2R,3S)-Butan-1,2,3,4-tetrol), best known as Erythritol is a naturally occurring four-carbon sugar alcohol belonging to the family of sugar alcohols also known as polyols, with no calorific value, found in many fruits and vegetables, mushrooms and in fermented foods such as soy sauce. Its caloric value is almost zero.

The calorific value of erythritol is approximately 1/20th of the calorific capacity compared to cane sugar and 1/15th of the caloric capacity compared to xylitol, The sweetness sensation of erythritol is approximately 70% of that of cane sugar.

Industrially it occurs as a fine white crystalline powder stable at high temperatures.

What it is used for and where

Food

Ingredient included in the list of European food additives as  E968.

Used as a sweetener, erythritol is widely used in a variety of food and oral hygiene products as a sugar substitute. It is frequently used in baked goods such as cakes, biscuits and biscuits at a level of up to 10% to increase baking stability and shelf life by adding softness and freshness to products. It has the prerogative of making the dough more compact. In particular, in sweets, erythritol, which crystallises quickly, provides a good glossy patina and does not absorb moisture. In candies, erythritol controls crystallisation better when combined with maltitol.

Medical
This review thoroughly analyzes the anti-diabetic and antihyperglycemic effects as well as other metabolic effects of xylitol and erythritol using articles published in PubMed since the 1960s, containing research done on experimental animals and humans (1).

Oral health studies revealed that erythritol can reduce dental plaque weight, reduce dental plaque acids, reduce counts of Streptococcus mutans in saliva and dental plaque, and reduce the risk for dental caries better than sorbitol and xylitol, resulting in fewer tooth restorations by dentist intervention (2).

Besides its more well-known use as a sweetener, erythritol can also be employed as a protective or moisturizing agent in ophthalmic formulations. Specifically:

1. Osmoprotective Effect
   Erythritol (like other sugar alcohols) has the ability to protect the cells on the ocular surface from osmotic stress—that is, fluctuations in salt and fluid concentration. In practice, it helps keep the eyes hydrated, especially in cases of dry eyes or prolonged contact lens use.

2. Compatibility with the Ocular Environment
   Since it is a relatively small molecule and well-tolerated, erythritol does not irritate the eye. On the contrary, it provides a sort of “cushion” of hydration.

3. Formulation Stability
   Adding small polyols to eye drops can improve the overall stability of the product and contribute to good comfort during application.

Cosmetics

Erythritol acts as a moderate humectant and moisturiser on the skin and is authorised for the following functions:

Humectant. Hygroscopic compound used to minimise water loss in the skin and to prevent it from drying out by facilitating faster and greater absorption of water into the stratum corneum of the epidermis.  The epidermis is the most superficial of the three layers that make up human skin (epidermis, dermis and hypodermis) and is the layer that maintains hydration in all three layers. In turn, the epidermis is composed of five layers: horny, the most superficial, granular, spinous, shiny, and basal. Humectants have the ability to retain the water they attract from the air in the stratum corneum and have the function of moisturising the skin. They are best used before emollients, which are oil-based.

Moisturizing. This ingredient is responsible for preventing the evaporation of moisture from the skin and improving cellular activity. When exposed to cold or hot air currents, the skin absorbs water from its inner layer to compensate for the evaporated water. If the draught phenomenon persists, the stratum corneum is dry and, if at all, damaged.

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Other uses

Toothpastes. Erythritol has been recognised by the American Dental Association as an alternative to traditional sugars and as part of a comprehensive programme including proper dental hygiene. 

Personal care products such as hair care, oral hygiene, skin care, soaps and bath products, deodorants.

Animal feed. Animal feeds/poultry manure.

Cosmetics. 

Safety

A University of Cleveland, USA, study of healthy volunteers found that long-term erythritol intake is associated with an incident (three-year) risk of adverse cardiovascular events. The analysis found, after erythritol intake, an increase above the associated threshold in plasma erythritol levels and an increase in platelet reactivity (3). However, a more recent study finds it unlikely that dietary erythritol is mediating these associations, rather reflecting dysregulated PPP due to impaired blood glucose or a glucose-rich diet (4).

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Erythritol  studies

Typical optimal commercial product characteristics Erythritol 

• Molecular Formula   C₄H₁₀O₄
• Linear Formula    HOCH₂[CH(OH)]₂CH₂OH
• Molecular Weight 122.12 g/mol
• Exact Mass    122.057907
• CAS    149-32-6 10030-58-7, 188346-77-2, 868541-49-5, 882981-67-1, 1646188-83-1, 1798874-12-0, 2075830-99-6, 909878-64-4
• EC Number    205-737-3
• IUPAC  (2S,3R)-butane-1,2,3,4-tetrol
• InChI=1S/C4H10O4/c5-1-3(7)4(8)2-6/h3-8H,1-2H2/t3-,4+  
• InChl Key      UNXHWFMMPAWVPI-ZXZARUISSA-N
• SMILES   C(C(C(CO)O)O)O
• DSSTox Substance ID: DTXSID6043919
• UNII RA96B954X6
• NSC Number 760400 8099
• Beilstein/REAXYS Number 1719753
• MDL number MFCD00004710
• PubChem Substance ID 329749381

Synonyms:

• Phycitol
• Erythrite
• Erythrit
• Phycite
• Erythrol
• i-Erythritol
• (2R,3S)-butane-1,2,3,4-tetrol
• meso-1,2,3,4-Tetrahydroxybutane
• erythro-tetritol
• 1,2,3,4-Butanetetrol, (2R,3S)-rel-
• (2R,3S)-rel-Butane-1,2,3,4-tetraol
• Butanetetrol
• Mesoerythritol
• (2r,3s)-butane-1,2,3,4-tetraol
• SMR000112220
• (2S,3R)-butane-1,2,3,4-tetrol

References______________________________________________________________________

(1) Metabolic effects of the natural sweeteners xylitol and erythritol: A comprehensive review. Wölnerhanssen BK, Meyer-Gerspach AC, Beglinger C, Islam MS. Crit Rev Food Sci Nutr. 2019 Jun 16:1-13. doi: 10.1080/10408398.2019.1623757

Abstract. Xylitol and erythritol are widely used in a variety of food and oral care products as sugar substitutes. Although a number of studies have been conducted on the health benefits of xylitol since the 1960s, erythritol only attracted the attention of researchers during the early 1990s. Historically, researchers mainly focused on the effects of xylitol and other sugar alcohols on oral and dental healthcare while the anti-diabetic or antihyperglycemic effects have only been revealed recently. Though a few reviews have been published on the health benefits of sugar alcohols in the last few decades, none of them closely evaluated the antihyperglycemic potential and underlying mechanisms, particularly with a focus on xylitol and erythritol. The current review thoroughly analyzes the anti-diabetic and antihyperglycemic effects as well as other metabolic effects of xylitol and erythritol using articles published in PubMed since the 1960s, containing research done on experimental animals and humans. This review will help researchers ascertain the controversies surrounding sugar alcohols, investigate further beneficial effects of them as well as aid food industries in exploring the possibilities of using sugar alcohols as anti-diabetic supplements in diabetic foods and food products.

(2) Erythritol Functional Roles in Oral-Systemic Health.  de Cock P.  Adv Dent Res. 2018 Feb;29(1):104-109. doi: 10.1177/0022034517736499.

Abstract. Erythritol belongs chemically to the family of polyols (or sugar alcohols), yet it is metabolized by animals and humans very differently compared to all other polyols. While polyols have been used traditionally (for about 80 y) to replace sugar in sweet foods to reduce demineralization of tooth enamel and to reduce postprandial blood glucose levels, benefits achieved merely through the absence of sugar, emerging evidence shows that erythritol can play a number of functional roles to actively support maintenance of oral and systemic health. Oral health studies revealed that erythritol can reduce dental plaque weight, reduce dental plaque acids, reduce counts of mutans streptococci in saliva and dental plaque, and reduce the risk for dental caries better than sorbitol and xylitol, resulting in fewer tooth restorations by dentist intervention. Systemic health studies have shown that erythritol, unlike other polyols, is readily absorbed from the small intestine, not systemically metabolized, and excreted unchanged within the urine. This metabolic profile renders erythritol to be noncaloric, to have a high gastrointestinal tolerance, and not to increase blood glucose or insulin levels. Published evidence also shows that erythritol can act as an antioxidant and that it may improve endothelial function in people with type 2 diabetes. This article reviews the key research demonstrating erythritol's oral and systemic health functionalities and underlying mechanisms.

(3) Witkowski M, Nemet I, Alamri H, Wilcox J, Gupta N, Nimer N, Haghikia A, Li XS, Wu Y, Saha PP, Demuth I, König M, Steinhagen-Thiessen E, Cajka T, Fiehn O, Landmesser U, Tang WHW, Hazen SL. The artificial sweetener erythritol and cardiovascular event risk. Nat Med. 2023 Feb 27. doi: 10.1038/s41591-023-02223-9. 

(4) Mazi TA, Stanhope KL. Erythritol: An In-Depth Discussion of Its Potential to Be a Beneficial Dietary Component. Nutrients. 2023 Jan 1;15(1):204. doi: 10.3390/nu15010204. 

Abstract. The sugar alcohol erythritol is a relatively new food ingredient. It is naturally occurring in plants, however, produced commercially by fermentation. It is also produced endogenously via the pentose phosphate pathway (PPP). Consumers perceive erythritol as less healthy than sweeteners extracted from plants, including sucrose. This review evaluates that perspective by summarizing current literature regarding erythritol's safety, production, metabolism, and health effects. Dietary erythritol is 30% less sweet than sucrose, but contains negligible energy. Because it is almost fully absorbed and excreted in urine, it is better tolerated than other sugar alcohols. Evidence shows erythritol has potential as a beneficial replacement for sugar in healthy and diabetic subjects as it exerts no effects on glucose or insulin and induces gut hormone secretions that modulate satiety to promote weight loss. Long-term rodent studies show erythritol consumption lowers body weight or adiposity. However, observational studies indicate positive association between plasma erythritol and obesity and cardiometabolic disease. It is unlikely that dietary erythritol is mediating these associations, rather they reflect dysregulated PPP due to impaired glycemia or glucose-rich diet. However, long-term clinical trials investigating the effects of chronic erythritol consumption on body weight and risk for metabolic diseases are needed. Current evidence suggests these studies will document beneficial effects of dietary erythritol compared to caloric sugars and allay consumer misperceptions.