Sugar substitute: Key facts for their use – A review

Xylitol

Five-carbon sugar alcohol derived primarily from forest and agricultural materials. Xylitol was used initially by diabetics as its metabolism was considered to be insulin- independent.^[12] It is naturally found in low concentrations in the fibers of many fruits and vegetables and can be extracted from various berries, oats, and mushrooms, as well as fibrous material such as corn husks and sugar cane bagasse, and birch.^[10]

Uses – xylitol is a “tooth-friendly” non-fermentable sugar alcohol. Virtually all chewing gum sold in Finland is sweetened with xylitol. Specific brands of sugar-free gum containing xylitol include stride and trident. Finland in the 1970s found that a group chewing sucrose gum had 2.92 decayed, missing, or filled (dmf) teeth compared to 1.04 in the group chewing xylitol gums. In another study, researchers had mothers give xylitol gum to their children 3 months after delivery until they were 2 years old. The researchers found that children in the xylitol group had “a 70% reduction in cavities (dmf).”^[13] Xylitol also has potential as a treatment for osteoporosis. A group of Finnish researchers has found that dietary xylitol prevents weakening of bones in laboratory rats, and actually improves bone density. Studies have shown that xylitol chewing gum can help prevent ear infections (acute otitis media); the act of chewing and swallowing assists with the disposal of earwax and clearing the middle ear, while the presence of xylitol prevents the growth of bacteria in the Eustachian tubes (auditory tubes or pharyngotympanic tubes) which connect the nose and ear.^[13] A recent report suggests that consumption of xylitol may help control oral infections of candida yeast; in contrast, galactose, glucose, and sucrose may increase proliferation. Xylitol has an antimicrobial effect on bacteria such as Streptococcus pneumoniae and can be used to prevent ear infections (otitis media) in children, as found in a study by Tapiainen. For ear infections, xylitol can be administered as a nasal spray or by chewing gum, with chewing gum being the preferred method since chewing and swallowing helps massage the Eustachian tubes, which helps with lymph flow.^[14]

Safety issues – during toxicity studies of xylitol by the Huntingdon Research Centre in England, it was found that mice ingesting diets with the highest xylitol content (10% and 20%) showed an increase in urinary bladder calculi, epithelial hyperplasia, and neoplasia of the bladder. Xylitol can be converted, through glycollate, to oxalate, which appears in the urine and can accumulate to form calcium oxalate crystals. The adverse effects observed in animal studies, such as pelvic nephrocalcinosis and bladder calculi, were induced by gross physiological and/or nutritional disturbance related to very high dose levels of the test compound.^[15] Therefore xylitol at a dose high enough to form bladder stones may serve as a tumor promoter rather than a true carcinogen.

Sorbitol

Sorbitol is also known as glucitol, a sugar alcohol that the human body metabolizes slowly. It is obtained by the reduction of glucose, changing the aldehyde group to an additional hydroxyl group.^[11] It was introduced in the diet of diabetics as early as 1929. In the 1970’s it also made a mark in the field of dentistry when various experiments were conducted to check the cariogenicity of sorbitol. Though Streptococcus mutans have enzymes to degrade sorbitol, the fermentation process is slow and hence very little drop in pH of the dental plaque was recorded after the ingestion of sorbitol as compared to the rapid drop following the use of sucrose.^[16]

Uses – as a nutritive sweetener because it provides dietary energy: 2.6 kcal/g versus the average 4 kcal for carbohydrates. It often is used in diet foods (including diet drinks and ice cream), mints, cough syrups, and sugar-free chewing gum. It also occurs naturally in many stone fruits and berries from trees of the genus Sorbus.^[17] Sorbitol can be used as a non- stimulant laxative through an oral suspension or enema. It works by drawing water into the large intestine, thereby stimulating bowel movements. Sorbitol is used in bacterial culture media to distinguish Escherichia coli 0154:H7 from most other strains of E. coli. Sorbitol often is used in mouth wash and toothpaste. Some transparent gels can be made only with sorbitol, as it has a refractive index sufficiently high for transparent formulations.

Adverse effects – sorbitol may aggravate irritable bowel syndrome, and similar gastrointestinal conditions, resulting in severe abdominal pain for those affected, even from small amounts ingested. Ingesting large amounts of sorbitol can lead to abdominal pain, gas, and mild to severe diarrhea. Sorbitol ingestion of 20 g/day as sugar-free gum has led to severe diarrhea leading to an unintended weight loss of 11 kg in a woman originally weighing 52 kg; another patient required hospitalization after habitually consuming 30 g/day.^[16]

Thaumatin

It consists of 207 amino acids and has identical amino acid sequences except for five residues. These proteins are about 100,000 times sweeter than sucrose on a molar basis and 300 times sweeter on a weight basis.^[6]

Uses – thaumatin is permitted as a sweetener in ice cream and sweets at levels up to 50 mg/kg and as a taste enhancer in soft drinks, desserts and dairy products at levels up to 0.5 mg/l and 5 mg/kg, respectively.^[18] Thaumatin is effective at masking bitter notes often associated with pharmaceuticals or vitamins. Used at 20–400 ppm in pills and tablets, its long-lasting effect covers strongly bitter aftertastes and leaves a pleasant feeling in the mouth. Thaumatin can also be useful for masking astringency and off-flavors.^[19]

Like other proteins, thaumatin is predicted to have a mainly beta structure, with a high content of beta-turns and little helix. Tobacco cells exposed to gradually increased salt concentrations develop a greatly increased tolerance to salt, due to the expression of osmotin, a member of the protein family. Wheat plants attacked by barley powdery mildew express a PR protein, which results in resistance against that infection. The similarity between this protein and other proteins to the maize alpha-amylase/trypsin inhibitor has suggested that proteins may act as some form of inhibitor.^[11]

Stevioside

Stevioside and related compounds are responsible for the sweet taste of Stevia leaves.^[20] Due to the high concentration of such sweet principles in leaves of Stevia plants, these are known as a honey leaf of sweet chrysanthemum.

Uses – stevia-based sweeteners fit well into this space, offering a combination of favorable attributes: High intensity and zero calories. There are two distinct markets: Specifically used for diabetic patients as a low calorie/dietetic segment and other as a nutritive sweetener which can be used as an alternative to marketed sugar (i.e., corn syrup, fructose, glucose, and sucrose).^[21]

Recently, the stability of stevioside during different processing and storage conditions has been evaluated in tea and coffee beverages. Stevioside at elevated temperature for 1 h showed good stability up to 120°C. In aqueous solution, stevioside is remarkably stable in the pH range of 2–10. This knowledge seems to be essential for its effective application in hot coffee and tea beverages. It is anticipated that usage of stevioside in various food formulations, i.e., herbal tea, bakery, confectionery items, toothpaste, mouth refreshers, candies, and chewing gums may protect from the mentioned bacterium.^[21]

Erythritol

It is a sugar alcohol (or polyol) that has been approved for use as a food additive in the United States^[22] and throughout much of the world. Erythritol is 60–70% as sweet as sucrose (table sugar), yet it is almost noncaloric,^[23] does not affect blood sugar, does not cause tooth decay, and is partially absorbed by the body, excreted in urine and feces. Under U.S. Food and Drug Administration (FDA) labeling requirements, it has a caloric value of 0.2 calories per gram (95% less than sugar and other carbohydrates), though nutritional labeling varies from country to country.

It is used in the beverage industry in the USA and Japan. It can also be used in food manufacture and chocolate, though usually, it needs to be mixed with other sweeteners to achieve the required texture and sweetness level. It is heat stable and can be used for cooking at home. It is a major ingredient of Truvia sweetener.^[24]

Isomalt

A type of sugar alcohol, which is primarily used for its sugar- like physical properties. It has only a small impact on blood sugar levels and does not promote tooth decay.^[25]

Uses – it does magic with flavors with its pleasant sweetness, enhances subtle, and fine flavors, such as peach, melon, passion fruit, and vanilla. The pure, natural taste of isomalt never overlays flavors but releases their full potential. It is very useful for confectioners and chefs for making showpieces as it is much more resistant to crystallization and more malleable than sugar.

Adverse effects – the reason that isomalt may prove upsetting to the stomach is because the body treats it as a dietary fiber instead of as a simple carbohydrate. Therefore, like most fibers, it can increase bowel movements and it passes through the bowel in virtually undigested form.^[26]

Miraculin

It was sold as Miralin Miracle Fruit Drops (Miralin Co.), to be chewed before meals or snacks.^[6] It has been suggested that the miraculin protein can change the structure of taste receptors on the cells of the tongue.^[27]

Uses – it is effective in sweetening citrus fruits, berries, yogurt, and other sour foods but does not sweeten cereals, cocoa, coffee, etc. Miracle fruit is available as freeze-dried granules or in tablets – this form has a longer shelf life than fresh fruit. Tablets are made from compressed freeze-dried fruit which causes the texture to be clearly visible even in tablet form.^[28] However, because manufacturers were unable to document their claims of efficacy in weight and reduced caloric intake, miraculin has been withdrawn from the market in the United States.^[6]

Dihydrochalcone sweeteners

The sweetness of the dihydrochalcones is many times greater than sucrose; 75 however, unlike sugar, the dihydrochalcone sweetness is relatively slow in onset and is lingering. This after taste can be described as cooling like menthol, or licorice-like. Dihydrochalcones are stable over a broad range of temperatures, in aqueous solution, and in acids at normal temperature and therefore, potentially useful in fruits and carbonated beverage products.^[7]

Uses – neohesperidin DH is permitted in a range of food products and beverages. Among these are desserts, yogurt, ice-cream, baked goods, jam, preserves, marmalade, soft drinks, sweets, mustard, and sauces. The permitted levels of use vary from 50 to 150 mg/kg depending on the food category.^[18-46]

Monellin

It is a sweet protein, also known as serendipity berry, it was first reported as carbohydrate.^[29] Monellin, thaumatin, and miraculin are the only taste-active proteins that have been currently characterized. Sweet protein monellin is approximately 3000 times sweeter than sugar. However, the protein has a slow onset of sweetness and a lingering aftertaste. The sweetness of monellin is pH and temperature- dependent.^[30]

Uses – it can be useful for sweetening some foods and drinks, as it is a protein readily soluble in water due to its hydrophilic properties. However, it may have limited application because it denatures under high-temperature conditions, which makes it unsuitable for processed food. It may be relevant as non-carbohydrate tabletop sweetener, especially for individuals such as diabetics who must control their sugar intake.^[31]

Aspartame

It is about 200 times sweeter than sugar and is readily dissolvable in water. It has a sweet taste without the bitter chemical or metallic aftertaste reported in other artificial sweeteners. In addition to sweetening foods, aspartame is used to reduce calories, and intensify and extend fruit flavors.^[17]

Aspartame is unstable under conditions of prolonged heating and is inappropriate for use in cooking and baking (Kroger et al., 2006). Aspartame also decomposes in liquids during prolonged storage. Aspartame-containing products are labeled to reflect these issues. Breakdown products include metabolic breakdown products (aspartic acid, phenylalanine, and methanol) and diketopiperazine. Breakdown results in loss of sweetness.^[32]

Uses – enhances and extends flavors, does not promote tooth decay. Aspartame is an FDA approved, safe sweetening agent, and flavor enhancer that can be substituted for sugar in the diet.^[16]

Saccharin

It is an aromatic organic compound used mainly in the form of its sodium salt. The consumption of saccharin has increased dramatically in many countries.^[33]

Uses – about 70% of the total amount used in United States and Canada has been used in – diet soft drinks; 13% in dietetic foods (e.g., canned fruits, gelatin desserts, jams, and ice cream); 12% in products sold at retail for table use; and the remaining 5% in miscellaneous products such as mouthwashes, cosmetics, and medicinal preparations.

Safety issues – controversy regarding the safety of saccharin for human consumption was well underway. The possibility of a link between the use of saccharin and the risk of bladder cancer has been investigated; some studies found a weak positive association.^[34] The status of saccharin as a possible over-the-counter product or the prescription item is still indeterminate.^[6]

Cyclamates

At 1% dietary levels cyclamates produce a minimal laxative effect. Evidence indicates that this effect is attributable to the osmotic action of unabsorbed cyclamate in the intestine.^[6]

It was banned because when embedded with cholesterol in a pellet in mouse bladders, or fed to rats at a dosage 50 times the daily maximum recommended for humans by the World Health Organization (WHO), induced bladder cancer. Experiments detected bladder cancer in 7–20 male rats treated. The animals received daily amounts equivalent to the total cyclamate contained in at least 500 eight- ounce bottle of a typical diet soft drink. The justification for such high dosage was to improve the chances of cancer detection. Solids (e.g., sodium stearate) can induce bladder cancer. Furthermore, a common rat bladder parasite also induces cancer. Recently a panel of scientists assembled by the National Cancer Institute reviewed more than 20 new animal-feeding studies and concluded that there was no firm evidence that cyclamates cause cancer, birth defects, or genetic damage. Cyclamate and saccharin may be tumor promoters rather than true carcinogens.^[35]

Acesulfame K

It is a calorie-free sweetener that has been used in foods and beverages. The ingredient, which is 200 times sweeter than sugar, has been used in numerous foods in the United States since 1988. In the U.S., it is used in such products as candies, baked goods, frozen desserts, beverages, dessert mixes, and tabletop sweeteners. More than 90 studies have demonstrated the safety of acesulfame potassium. The ingredient is currently used in more than 4000 foods and beverages in about 90 countries around the world.^[36]

Uses – it does not break down under high temperatures and so can be used in all processed foods and in cooking. It is literally thousands of products. Other than as a zero-calorie sweetener it has no other use. Acesulfame K is not harmful to teeth and suitable for diabetic patients. It is one of the cheapest sweeteners. Works very well with other sweeteners including aspartame and sucralose. It is heat stable and is suitable for cooking and in processed foods.

Safety issues – Acesulfame K shows no evidence of cariogenicity, mutagenicity, cytotoxicity, or teratogenicity. Pharmacokinetic tests indicate rapid and almost complete absorption. Excretion, preponderantly through the urine, is also complete because the compound does not accumulate in tissues or organs.^[37]

Alitame

Like aspartame and neotame, alitame is a sweetener made from amino acids. Alitame is 2000 times sweeter than sugar. Only extremely small amounts would need to be used in a food or beverage, and the caloric contribution of alitame would, therefore, be negligible even though one of its components is metabolized.^[38]

Uses – it is useful for diabetics and it is harmless to teeth. It is a totally artificial sweetener but it appears to be safe. Certainly, it is a better choice than Aspartame. Not well known or widely used, but has significant potential nonetheless. Unlike aspartame, phenylaniline is not a by-product of digestion and so it is suitable for people with the genetic disorder called phenylketonuria. It has quite a good taste and less aftertaste than aspartame. It is also more stable under heat though not as good as some sweeteners in this regard. So far, unlike aspartame, no side effects have been reported. Due to high cost, production has recently ceased. It is sold as Aclame.^[18]

Lactitol

It has a good flavor with no aftertaste. It has two calories per gram (50% of sugar) but it has only 40% of the sweetness. Hence, on its own, it is of no special use as part of a calorie-controlled diet, sugar is better. It does, however, have a very low glycemic index and is consequently suitable for diabetics. It also has other unique properties which make it suitable as a replacement for sugar in certain applications.^[38]

Uses – used in a variety of low food energy or low-fat foods. It has high heat stability, which it popular for baking. It is used in sugar-free candies, cookies (biscuits), chocolate, and ice cream. Lactitol also promotes colon health as a probiotic. Because of poor absorption, lactitol only has 2.4 calories (9 kJ) per gram, compared to four calories (17 kJ) per gram for typical carbohydrates. Lactitol is listed as an excipient in some prescription drugs, such as Adderall. Lactitol is a laxative and is used to prevent or treat constipation, for example, under the trade name importal. Lactitol in combination with ispaghula husk is an approved combination for idiopathic constipation as a laxative. Osmotic laxatives are often prescribed as first- line therapy in the management of constipation in children and adults.^[39]

Safety issues – lactitol can cause cramping, flatulence, and diarrhea in some individuals. Because humans lack a suitable enzyme in the small intestine to digest it, a majority of lactitol reaches the large intestine, where it then becomes fermentable to gut microbes (prebiotic) and can pull water into the gut by osmosis, causing a laxative effect. Other than this, lactitol seems perfectly safe.^[39]

High-fructose corn syrups (HFCS)

HFCS (also called glucose-fructose, isoglucose, and glucose-fructose syrup) 139,140 is a sweetener made from corn starch that has been processed by glucose isomerase to convert some of its glucose into fructose. HFCS, particularly one containing 55% of sucrose are being substituted for sucrose, invert sugar, and glucose syrups for use in processed foods and as a liquid table-top sweetener. The estimated use of HFCS for 1980 was 19 pounds per capita per year (8.6 kg). Soft drink manufacturers are the main users of HFCS, but HFCS use is increasing at a dramatic rate in other food industries such as baking, canning, processed foods, and dairy products.^[6]

Uses – HFCS is found in various products ranging from cookies, sodas, crackers, and cereals, which makes it hard to avoid when consuming processed foods and drinks. It enhances other flavors because its sweetness is detected quickly and early by the taste buds, but does not linger, resulting in a clearer and crisper perception of other flavors. Maintains freshness and prolongs shelf life through improved moisture control and less microbial spoilage, resulting in firmer canned fruits and less freezer burn in frozen fruits. HFCS supplies are more reliable and predictable and its price is less volatile than that of sucrose; it is also slightly cheaper when costs are adjusted for equal sweetening power.^[40]