Sugar substitute

A sugar substitute is a food additive that provides a sweet taste like that of sugar while containing significantly less food energy than sugar-based sweeteners, making it a zero-calorie (non-nutritive) or low-calorie sweetener. Artificial sweeteners may be derived through manufacturing of plant extracts or processed by chemical synthesis. Sugar alcohols such as erythritol, xylitol, and sorbitol are derived from sugars. In 2017, sucralose was the most common sugar substitute used in the manufacture of foods and beverages; it had 30% of the global market, which was projected to be valued at $2.8 billion by 2021.
In 1969, cyclamate was banned for sale in the US by the Food and Drug Administration. As of 2018, there is no strong evidence that non-sugar sweeteners are either unsafe or result in improved health outcomes.
When these sweeteners are provided for restaurant customers to add to beverages such as tea and coffee, they are provided in small colored paper packets (see image); in North America, the colors are typically "blue" for aspartame, "pink" for saccharin (US) or cyclamate (Canada), "yellow" for sucralose, "orange" for monk fruit extract, and "green" for stevia. These sweeteners are also a fundamental ingredient in diet drinks to sweeten them without adding calories.
Types.
"High-intensity sweeteners" – one type of sugar substitute – are compounds with many times the sweetness of sucrose, common table sugar. As a result, much less sweetener is required and energy contribution is often negligible. The sensation of sweetness caused by these compounds (the "sweetness profile") is sometimes notably different from sucrose, so they are often used in complex mixtures that achieve the most intense sweet sensation.
If the sucrose (or other sugar) that is replaced has contributed to the texture of the product, then a bulking agent is often also needed. This may be seen in soft drinks or sweet teas that are labeled as "diet" or "light" that contain artificial sweeteners and often have notably different mouthfeel, or in table sugar replacements that mix maltodextrins with an intense sweetener to achieve satisfactory texture sensation.
In the United States, six high-intensity sugar substitutes have been approved for use: aspartame, sucralose, neotame, acesulfame potassium (Ace-K), saccharin, and advantame. Food additives must be approved by the FDA, and sweeteners must be proven as safe via submission by a manufacturer of a GRAS document. The conclusions about GRAS are based on a detailed review of a large body of information, including rigorous toxicological and clinical studies. GRAS notices exist for two plant-based, high-intensity sweeteners: steviol glycosides obtained from stevia leaves ("Stevia rebaudiana") and extracts from "Siraitia grosvenorii", also called "luo han guo" or monk fruit.
Cyclamates are used outside the United States, but are prohibited from being used as a sweetener within the United States. The majority of sugar substitutes approved for food use are artificially synthesized compounds. However, some bulk plant-derived sugar substitutes are known, including sorbitol, xylitol and lactitol. As it is not commercially profitable to extract these products from fruits and vegetables, they are produced by catalytic hydrogenation of the appropriate reducing sugar. For example, xylose is converted to xylitol, lactose to lactitol, and glucose to sorbitol.
Sorbitol, xylitol and lactitol are examples of sugar alcohols (also known as polyols). These are, in general, less sweet than sucrose but have similar bulk properties and can be used in a wide range of food products. Sometimes the sweetness profile is fine-tuned by mixing with high-intensity sweeteners.
Allulose.
Allulose is a sweetener in the sugar family, with a chemical structure similar to fructose. It's naturally found in figs, maple syrup, and some fruit. While it comes from the same family as other sugars, it does not substantially metabolize as sugar in the body. The FDA recognizes that allulose does not act like sugar, and as of 2019, no longer requires it to be listed with sugars on U.S. nutrition labels. Allulose is about 70% as sweet as sugar, which is why it's sometimes combined with high-intensity sweeteners to make sugar substitutes.
Acesulfame potassium.
Acesulfame potassium (Ace-K) is 200 times sweeter than sucrose (common sugar), as sweet as aspartame, about two-thirds as sweet as saccharin, and one-third as sweet as sucralose. Like saccharin, it has a slightly bitter aftertaste, especially at high concentrations. Kraft Foods has patented the use of sodium ferulate to mask acesulfame's aftertaste. Acesulfame potassium is often blended with other sweeteners (usually aspartame or sucralose), which give a more sucrose-like taste, whereby each sweetener masks the other's aftertaste and also exhibits a synergistic effect in which the blend is sweeter than its components.
Unlike aspartame, acesulfame potassium is stable under heat, even under moderately acidic or basic conditions, allowing it to be used as a food additive in baking or in products that require a long shelf life. In carbonated drinks, it is almost always used in conjunction with another sweetener, such as aspartame or sucralose. It is also used as a sweetener in protein shakes and pharmaceutical products, especially chewable and liquid medications, where it can make the active ingredients more palatable.
Aspartame.
Aspartame was discovered in 1965 by James M. Schlatter at the G.D. Searle company. He was working on an anti-ulcer drug and accidentally spilled some aspartame on his hand. When he licked his finger, he noticed that it had a sweet taste. Torunn Atteraas Garin oversaw the development of aspartame as an artificial sweetener. It is an odorless, white crystalline powder that is derived from the two amino acids aspartic acid and phenylalanine. It is about 180–200 times sweeter than sugar and can be used as a tabletop sweetener or in frozen desserts, gelatins, beverages, and chewing gum. When cooked or stored at high temperatures, aspartame breaks down into its constituent amino acids. This makes aspartame undesirable as a baking sweetener. It is more stable in somewhat acidic conditions, such as in soft drinks. Though it does not have a bitter aftertaste like saccharin, it may not taste exactly like sugar. When eaten, aspartame is metabolized into its original amino acids. Because it is so intensely sweet, relatively little of it is needed to sweeten a food product, and is thus useful for reducing the number of calories in a product.
The safety of aspartame has been studied extensively since its discovery with research that includes animal studies, clinical and epidemiological research, and postmarketing surveillance, with aspartame being one of the most rigorously tested food ingredients to date. Although aspartame has been subject to claims against its safety, multiple authoritative reviews have found it to be safe for consumption at typical levels used in food manufacturing. Aspartame has been deemed safe for human consumption by over 100 regulatory agencies in their respective countries, including the UK Food Standards Agency, the European Food Safety Authority (EFSA) and Health Canada.
Cyclamate.
In the United States, the Food and Drug Administration banned the sale of cyclamate in 1969 after lab tests in rats involving a 10:1 mixture of cyclamate and saccharin (at levels comparable to humans ingesting 550 cans of diet soda per day) caused bladder cancer. This information, however, is regarded as "weak" evidence of carcinogenic activity, and cyclamate remains in common use in many parts of the world, including Canada, the European Union and Russia.
Mogrosides.
Mogrosides, extracted from monk fruit and commonly called "luo han guo", are recognized as safe for human consumption and are used in commercial products worldwide. As of 2017, it is not a permitted sweetener in the European Union, although it is allowed as a flavor at concentrations where it does not function as a sweetener. In 2017, a Chinese company requested a scientific review of its mogroside product by the European Food Safety Authority. It is the basis of McNeil Nutritionals's tabletop sweetener Nectresse in the United States and Norbu Sweetener in Australia.
Saccharin.
Apart from sugar of lead (used as a sweetener in ancient through medieval times before the toxicity of lead was known), saccharin was the first artificial sweetener and was originally synthesized in 1879 by Remsen and Fahlberg. Its sweet taste was discovered by accident. It had been created in an experiment with toluene derivatives. A process for the creation of saccharin from phthalic anhydride was developed in 1950, and, currently, saccharin is created by this process as well as the original process by which it was discovered. It is 300 to 500 times sweeter than sucrose and is often used to improve the taste of toothpastes, dietary foods, and dietary beverages. The bitter aftertaste of saccharin is often minimized by blending it with other sweeteners.
Fear about saccharin increased when a 1960 study showed that high levels of saccharin may cause bladder cancer in laboratory rats. In 1977, Canada banned saccharin due to the animal research. In the United States, the FDA considered banning saccharin in 1977, but Congress stepped in and placed a moratorium on such a ban. The moratorium required a warning label and also mandated further study of saccharin safety.
Subsequently, it was discovered that saccharin causes cancer in male rats by a mechanism not found in humans. At high doses, saccharin causes a precipitate to form in rat urine. This precipitate damages the cells lining the bladder (urinary bladder urothelial cytotoxicity) and a tumor forms when the cells regenerate (regenerative hyperplasia). According to the International Agency for Research on Cancer, part of the World Health Organization, "Saccharin and its salts was [sic] downgraded from Group 2B, possibly carcinogenic to humans, to Group 3, not classifiable as to carcinogenicity to humans, despite sufficient evidence of carcinogenicity to animals, because it is carcinogenic by a non-DNA-reactive mechanism that is not relevant to humans because of critical interspecies differences in urine composition."
In 2001, the United States repealed the warning label requirement, while the threat of an FDA ban had already been lifted in 1991. Most other countries also permit saccharin, but restrict the levels of use, while other countries have outright banned it.
The EPA has removed saccharin and its salts from their list of hazardous constituents and commercial chemical products. In a 14 December 2010 release, the EPA stated that saccharin is no longer considered a potential hazard to human health.
Stevia.
Stevia is a natural non-caloric sweetener derived from the "Stevia rebaudiana" plant, and is manufactured as a sweetener. It is indigenous to South America, and has historically been used in Japanese food products, although it is now common internationally. In 1987, the FDA issued a ban on stevia because it had not been approved as a food additive, although it continued to be available as a dietary supplement. After being provided with sufficient scientific data demonstrating safety of using stevia as a manufactured sweetener, such as Cargill and Coca-Cola, the FDA gave a "no objection" status as generally recognized as safe (GRAS) in December 2008 to Cargill for its stevia product, Truvia, for use of the refined stevia extracts as a blend of rebaudioside A and erythritol. 
In Australia, the brand Vitarium uses Natvia, a stevia sweetener, in a range of sugar-free children's milk mixes.
In August 2019, the FDA placed an import alert on stevia leaves and crude extracts – which do not have GRAS status – and on foods or dietary supplements containing them due to concerns about safety and potential for toxicity.
Sucralose.
The world's most commonly used artificial sweetener, sucralose is a chlorinated sugar that is about 600 times sweeter than sugar. It is produced from sucrose when three chlorine atoms replace three hydroxyl groups. It is used in beverages, frozen desserts, chewing gum, baked goods, and other foods. Unlike other artificial sweeteners, it is stable when heated and can therefore be used in baked and fried goods. Discovered in 1976, the FDA approved sucralose for use in 1998.
Most of the controversy surrounding Splenda, a sucralose sweetener, is focused not on safety but on its marketing. It has been marketed with the slogan, "Splenda is made from sugar, so it tastes like sugar." Sucralose is prepared from either of two sugars, sucrose or raffinose. With either base sugar, processing replaces three oxygen-hydrogen groups in the sugar molecule with three chlorine atoms.
The "Truth About Splenda" website was created in 2005 by The Sugar Association, an organization representing sugar beet and sugar cane farmers in the United States, to provide its view of sucralose. In December 2004, five separate false-advertising claims were filed by the Sugar Association against Splenda manufacturers Merisant and McNeil Nutritionals for claims made about Splenda related to the slogan, "Made from sugar, so it tastes like sugar". French courts ordered the slogan to no longer be used in France, while in the U.S. the case came to an undisclosed settlement during the trial.
Sucralose has been shown to cause insulin resistance in healthy persons, but only when consumed with carbohydrates. 
There are few safety concerns pertaining to sucralose and the way sucralose is metabolized suggests a reduced risk of toxicity. For example, sucralose is extremely insoluble in fat and, thus, does not accumulate in fatty tissues; sucralose also does not break down and will dechlorinate only under conditions that are not found during regular digestion (i.e., high heat applied to the powder form of the molecule). Only about 15% of sucralose is absorbed by the body and most of it passes out of the body unchanged.
Sugar alcohols.
Sugar alcohols, or polyols, are sweetening and bulking ingredients used in manufacturing of foods and beverages, particularly sugar-free candies, cookies, and chewing gums. As a sugar substitute, they typically are less-sweet than sugar and supply fewer calories (about a half to one-third fewer calories) than sugar, are converted to glucose slowly, and do not spike increases in blood glucose.
Sorbitol, xylitol, mannitol, erythritol, and lactitol are examples of sugar alcohols. These are, in general, less sweet than sucrose, but have similar bulk properties and can be used in a wide range of food products. The sweetness profile may be altered during manufacturing by mixing with high-intensity sweeteners.
Sugar alcohols are carbohydrates with a biochemical structure partially matching the structures of sugar and alcohol, although not containing ethanol. They are not entirely metabolized by the human body. They are found commonly in small quantities in some fruits and vegetables, and are commercially manufactured from different carbohydrates and starch.
Use.
Sugar substitutes are used instead of sugar for a number of reasons, including:
Acceptable daily intake levels.
In the United States, the FDA provides guidance for manufacturers and consumers about the daily limits for consuming high-intensity sweeteners, a measure called "Acceptable Daily Intake" (ADI). During their premarket review for all of the high-intensity sweeteners approved as food additives, FDA established an ADI defined as an amount in milligrams per kilogram of body weight per day (mg/kg bw/d), indicating that a high-intensity sweetener does not cause safety concerns if estimated daily intakes are lower than the ADI. FDA states: "An ADI is the amount of a substance that is considered safe to consume each day over the course of a person’s lifetime." For stevia (specifically, steviol glycosides), an ADI was not derived by the FDA, but by the Joint Food and Agricultural Organization/World Health Organization Expert Committee on Food Additives, whereas an ADI has not been determined for monk fruit. FDA also published estimates of sweetness intensity, called a "multiplier of sweetness intensity" (MSI) as compared to table sugar.
For the sweeteners approved as food additives, the ADIs in milligrams per kilogram of body weight per day are:
Stevia (pure extracted steviol glycosides) has an ADI of 4 and a MSI of 200 to 400, where for monk fruit, no ADI has been determined and the MSI is 250 to 400.
Sweetness.
Plant-derived.
The sweetness levels and energy densities are in comparison to those of sucrose.
Health effects.
Body weight.
Numerous reviews have concluded that the association between body weight and non-nutritive sweetener usage is inconclusive. Observational studies tend to show a link to high body weight, while randomized controlled trials instead show a small causal weight loss. Other reviews concluded that use of non-nutritive sweeteners instead of sugar reduces body weight.
Metabolic disorder.
A 2015 review found that there is no evidence that non-caloric sweeteners cause metabolic disorders in humans.
A review article suggests there is a link between sucralose consumption and insulin resistance in susceptible individuals, due to sucralose changing the composition of gut microbiota.
Cancer.
Reviews in 2017 and 2015 found no evidence for increased cancer risk from using artificial sweeteners.
Sugar alcohols.
Sugar alcohols, or polyols, are sweetening and bulking ingredients used in manufacturing of foods and beverages. As a sugar substitute, they supply fewer calories (about a half to one-third fewer calories) than sugar, are converted to glucose slowly, and do not spike increases in blood glucose.
Comparison to sugar.
Reviews and dietetic professionals have concluded that moderate use of non-nutritive sweeteners as a safe replacement for sugars can help limit energy intake and assist with managing blood glucose and weight.