A sugar substitute is a food additive that duplicates the effect of sugar or corn syrup in taste, but usually has less food energy. Some sugar substitutes are natural and some are synthetic. Those that are not natural are, in general, referred to as artificial sweeteners.
An important class of sugar substitutes are known as high-intensity sweeteners. These are compounds with sweetness that is many times that of sucrose, common table sugar. As a result, much less sweetener is required, and energy contribution 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 natural sweet sensation.
If the sucrose (or other sugar) replaced has contributed to the texture of the product, then a bulking agent is often also needed. This may be seen in soft drinks labeled as "diet" or "light," which 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, five intensely-sweet sugar substitutes have been approved for use. They are saccharin, aspartame, sucralose, neotame, and acesulfame potassium. There is some ongoing controversy over whether artificial sweeteners are health risks. This controversy is fueled by anecdotal reports and sometimes poorly-controlled studies that have gained publicity via the internet and popular press. Scientifically-controlled peer-reviewed studies have consistently failed to produce evidence of adverse effects caused by consumption of these products. There is also a herbal supplement, stevia, used as a sweetener. Controversy surrounds stevia's safety and there is a battle over its approval as a sugar substitute.
The majority of sugar substitutes approved for food use are artificially-synthesized compounds. However, some bulk natural sugar substitutes are known, including sorbitol and xylitol, which are found in berries, fruit, vegetables, and mushrooms. It is not commercially viable to extract these products from fruits and vegetables, so 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. Still other natural substitutes are known, but are yet to gain official approval for food use.
Some non-sugar sweeteners are polyols, also known as "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. Sometimes the sweetness profile is 'fine-tuned' by mixing high-intensity sweeteners. As with all food products, the development of a formulation to replace sucrose is a complex proprietary process.
Artificial sweeteners cost the food industry only a fraction of the cost of natural sweeteners in spite of the extremely high profit margins for manufacturers of artificial sweeteners. So it is not surprising that the food industry is promoting its "diet" or "light" products heavily, thus moving the customers over to its even more profitable artificially-sweetened products.
According to market analysts Mintel, a total of 3,920 products containing artificial sweeteners were launched in the US between 2000 and 2005. In 2004 alone, 1,649 artificially-sweetened products were launched. According to market analysts Freedonia, the US artificial sweetener market is set to grow at around 8.3% per year to $189 million in 2008.
Aspartame is currently the most popular sweetener in the US food industry, as the price has dropped significantly since the Monsanto patent expired in 1992. However, sucralose may soon replace it, as alternative processes to Tate & Lyle's patent seem to be emerging. According to Morgan Stanley, this can mean that the price of sucralose will drop by 30%.
Animal studies have convincingly proven that artificial sweeteners cause body weight gain. A sweet taste induces an insulin response, which causes blood sugar to be stored in tissues (including fat), but because blood sugar does not increase with artificial sugars, there is hypoglycemia and increased food intake the next time there is a meal. After a while, rats given sweeteners have steadily increased caloric intake, increased body weight, and increased adiposity (fatness). Furthermore, the natural responses to eating sugary foods (eating less at the next meal and using some of the extra calories to warm the body after the sugary meal) are gradually lost.
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 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.
Initial safety testing suggested that aspartame caused brain tumors in rats; as a result, the additive was held up in the United States for many years in the FDA's approval process. In 1980, the FDA convened a Public Board of Inquiry (PBOI) consisting of independent advisors charged with examining the purported relationship between aspartame and brain cancer. The PBOI's conclusions were unclear as to whether aspartame causes brain damage, and recommended against approving aspartame at that time, citing unanswered questions about cancer in laboratory rats. In 1981, FDA Commissioner Arthur Hull Hayes, newly appointed by President Ronald Reagan, approved aspartame as a food additive. He was closely associated with the artificial sweetener industry, having several close friends, most notably Donald Rumsfeld, former United States Secretary of Defense, and then the CEO of G.D. Searle. Hayes cited data from a single Japanese study that had not been available to the members of the PBOI, as his reason for approval.
Since the FDA approved aspartame for consumption, some researchers have suggested that a rise in brain tumor rates in the United States may be at least partially related to the increasing availability and consumption of aspartame. Some research, often supported by companies producing artificial sweeteners, has failed to find any link between aspartame and cancer or other health problems. A recent research showed a clear link between this substance and cancer; a link that may be sufficient evidence for the FDA to pull aspartame from the market. This research has led the Center for Science in the Public Interest to classify aspartame as a substance to be avoided in its Chemical Cuisine Directory. However, the EFSA's press release about the study, published on 5 May 2006, concluded that the increased incidence of lymphomas/leukaemias reported in treated rats was unrelated to aspartame, the kidney tumors found at high doses of aspartame were not relevant to humans, and that based on all available scientific evidence to date, there was no reason to revise the previously established Acceptable Daily Intake levels for aspartame.
Several European Union countries approved aspartame in the 1980s, with EU-wide approval in 1994. The European Commission Scientific Committee on Food reviewed subsequent safety studies and reaffirmed the approval in 2002. The European Food Safety Authority reported in 2006 that the previously established Adequate Daily Intake was appropriate, after reviewing yet another set of studies.
It has also been investigated and approved by the Joint Expert Committee on Food Additives of the United Nations Food and Agricultural Organization and World Health Organization.
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 a chlorinated sugar prepared from either 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, in order to provide its view of sucralose. In December of 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.
Safety concerns pertaining to sucralose revolve around the fact that it belongs to a class of chemicals called organochlorides, some types of which are toxic or carcinogenic; however, the presence of chlorine in an organic compound does not in any way ensure toxicity. The way sucralose is metabolized may suggest a reduced risk of toxicity. For example, sucralose is extremely insoluble in fat and thus does not accumulate in fat as do some other organochlorides; sucralose also does not break down or dechlorinate.